Method predicting development zones of secondary fracture-type reservoirs in sedimentary section
FIELD: physics; geophysics.
SUBSTANCE: invention relates to geology and can be used to predict development zones of secondary fracture-type reservoirs in a sedimentary section. The method involves detecting reflected seismic waves associated with a selected system of deposits; performing lithologic-petrophysical investigation of rock samples to determine the most probable genesis of secondary reservoirs; selecting lithotypes on which secondary fracture-type reservoirs are formed; drilling a well in anticline structures and determining the depth of occurrence of fold hinges, morphologic parameters of the structures, including maximum seam contortion, width, length, area and intensity of folding; using downhole logging results to determine secondary porosity; measuring formation pressure in test intervals; establishing a critical value of secondary porosity Kpvtcr; establishing a multidimensional correlation relationship of the secondary porosity Kpvt=f(i, gradp, J, Kpob, H), where i is the maximum seam contortion; gradp is the gradient of formation pressure; J=i/S is folding intensity; S is the surface area of the structure; Kpob is the overall porosity; H is the depth of occurrence of fold hinge; performing detailed field seismic survey on unstudied areas of the territory with a dense seismic grid through not more than 100 m; processing field seismic materials; detecting presence of anticline structures and deep faults; constructing seismic-geologic profiles along and across the detected structures; determining the depth of occurrence of vfold hinges and morphologic parameters of the structures; using the established relationship Kpob=f(H) to determine overall porosity at the depth of occurrence of the bedrock on newly detected structures; determining the predicted gradient of formation pressure; using the established multidimensional correlation relationship of secondary porosity Kpvt=f(i, gradp, J, Kpob, H) to predict the value of Kpvt; comparing Kpvt with the lower limit of Kpvtcr for the "reservoir-nonreservoir" boundary, which is then used to predict the probability of development of secondary fracture-type reservoirs, the expediency of drilling on said structures and the well drilling procedure. If Kpvt/Kpvtcr>1.2, it is expedient to drill on a profile of three dependent wells; if Kpvt/Kpvtcr=(0.7-1.2), drilling only one well in the crest of the structure is expedient.
EFFECT: high efficiency of prediction.
1 dwg, 5 tbl
The invention relates to the field of Geology and can be used for exploration of hydrocarbon deposits in the sedimentary cover, dedicated to the secondary reservoir, fracture type, and to select the location of prospecting, exploration and production wells.
There is a method of prediction of reservoir rocks fractured type in the composition of the sedimentary cover, including tectonophysical modeling simple structural forms observed in the case and the analysis of the mechanism and kinetics of formation of dislocation (cracks) of different types (Belousov V.V., gzowski M.V. Experimental tectonics. M.: Nedra, 1964, pp.118).
The disadvantage of this method is that, first, it does not take into account the data of seismic surveys, and therefore does not allow to model specific structural-geological structure of the considered section of this or that field and, secondly, it does not use information about the ability of different types of precipitation converted into sewers fracture type.
There is a method of forecasting of development zones secondary collectors in the Foundation (RF Patent No. 2085975, IPC G01V 1/28, 1997), including the interpretation of reflected seismic waves, attached to the sole of the sedimentary cover and one of the underlying acoustic boundary based on the data of geological and geophysical surveys in wells, lithol the th-petrophysical studies, they define the most probable Genesis of secondary collectors, and then allocate the lithotypes, which is the formation of secondary collectors, and determine the area of development of these lithotypes within the field, determine the speed of propagation of longitudinal waves in the selected lithotypes and developing them secondary reservoirs emit seismologist between the reflection from the base of the sedimentary cover and the reflection in the roof of the Foundation, taking into account the received lithologic-petrographic and speed characteristics perform quantitative interpretation changes the time interval between the reflected waves, limiting the selected seismographs, and the zone of maximum time interval is considered as the areas most likely to be the development of secondary collectors in the sedimentary cover.
The disadvantage of this method is that it can not be enough to reliably predict the development of secondary collectors fracture type in the sedimentary cover. In addition, this method is not considered unequal ability of rocks of different composition under the action of external forces to be crushed and converted into the fractured reservoir.
Known methods for the development of deposits of hydrocarbons in fractured reservoirs, n is an example of the method according to the patent of the USSR N 1806261, EV 43/30, 43/00, 1993, including the drilling of wells in the area of deposits and production of hydrocarbons through the production wells located within systems of faults of the reservoir, the location of which in the contour deposits pre-set. According to this method before drilling on the basis of geophysical studies and other data identified in the reservoir blocks, the boundaries between them and build a map of faults. Due to the high permeability zones of faults increases the flow rate and the target oil production. However, this method is not entirely satisfactory because it does not take into consideration the age of the formation of the faulting zones, and if they formed the ancient tectonics and at a later time are not subjected to tectonic movements, the likelihood of clogging of cracks in them is very high, which leads to a significant deterioration of reservoir properties of productive formation.
There is a method of developing oil deposits in tectonically complicated sedimentary strata on the patent of Russian Federation N 2067166, EV 43/20, 1996, including the determination of the existence of blocks of tectonic origin and their boundaries within the structure or area of the field according to the field of geophysical studies and research wells, the drill is the production and injection wells and oil production, where on the geophysical survey and received at wells survey data to calculate the coefficients of the tectonic deformation of the structure as a whole and its separate sections, determine the magnitude of the relative increment of the thickness of the deformed sections of the structure, determine the magnitude heterodynamic and geoanalytical potentials of the individual sections of the structure, calculate the coefficients inherited deformation across the floor of the basin. According to the above found values and ratios establish the presence of a deformed block structure with a raised and lowered position sedimentary strata relatively constant part of their boundaries and the boundaries of the deformed blocks establish the presence of active tectonic deformation zones. Drilling all categories operate outside of these areas, while producing wells have directly within blocks, and injection wells are placed in the border area units, especially in areas with the greatest change heterodynamic potential.
There is also known a method of developing oil fields in RF patent N 2057921, EV 43/30, 1996, which includes the drilling operation and injection wells, the specification of the path field, the follower of the spine of its development and operation modes of operation and injection wells, in which determine the stress state of the array, make the selection active tectonic zones in the Deposit area with the subsequent mapping of the stress state, injection wells have relatively more loaded and operating in the unloaded zones. According to these two ways to place the most likely hydrocarbon accumulations are determined from the stress-strain state of the array, assuming that the content of the fluids in tectonically stressed zones is reduced under the action of compression breeds high voltages with decreasing porosity, permeability, and natural moisture breeds, resulting fluids are pressed in tectonically unloaded zone. However, in these methods, as noted above, tectonically current conditions are considered to be constant, whereas in reality may be a total or partial clogging of the pore space, “overgrowing” cracks formed the ancient tectonics, which will lead to lower inflows of oil in the well and increase the costs of exploration and exploitation of the Deposit.
The closest in technical essence is "a Method for predicting development zones secondary reservoir fracture type in the sedimentary cover" (Patent No. 2183332, G01V 9/00, 10.06.2002), R is the overall processing of the reflected seismic waves, linked to a selected complex, based on the data of geological and geophysical surveys in wells, conducting lithologic-petrographic studies of rock samples to determine the most probable Genesis of secondary collectors, the selection of lithotypes, which is the formation of secondary collectors fracture type and the definition of the area of the development of these lithotypes within the field, and seismic time sections highlight the most common types of anticlinal structures, modeling the dynamics of their development on the basis of which determine the distribution of stresses, linear fracture density, orientation and radius of fractured zones, build dependencies between linear fracture density, radius fracture zones and amplitude simulated anticlinal structures on the basis of which predict areas most probable distribution of the secondary reservoir fracture type.
The disadvantages of this method include the difficulty in assessing the linear density of the cracks, their orientation and the radius of the zone of fracture, and the low correlation coefficient of these geological parameters with only one morphological parameter, the amplitude of the simulated anticlinal structures.
The technical result is to increase the efficiency of exploration for the development of hydrocarbon deposits by identifying zones of fracturing and optimization of inception of exploration and production wells on the anticlinal structures of the type based on information previously drilled structures and developed the criteria of presence of fractured reservoirs using the maximum information about the morphological characteristics of the structures, block porosity and values of reservoir pressure.
The technical result is achieved in that in the method for predicting development zones secondary reservoir fracture type in the sedimentary cover, including the processing of reflected seismic waves, linked to a selected range of sediments, taking into account data of geological and geophysical surveys in wells, conducting lithologic-petrographic studies of rock samples to determine the most probable Genesis of secondary collectors, the selection of lithotypes, which is the formation of secondary collectors fracture type according to the invention for drilled anticlinal structures determine the depth of castles folds, morphological parameters of the structures, including the maximum bending of the layers, width, length, area, intensity of folding, the results geophysical study of wells during drilling of these structures determine the values of secondary porosity, measured reservoir pressure at intervals of tests, establish the critical value of the secondary porosity - KVTCRset of multidimensional correlation tie the secondary porosity by the formula Qpvt=a·i+b·gradp+c·J+d·PBC+f·H, where i is the maximum bending of the layers; gradp - gradient reservoir pressure; J=i/S is the intensity of folding; S - area patterns; PBC - block porosity; H - depth of the castle folds; a, b, C, d, f are coefficients of proportionality defined for a specific region, not further studied areas conduct detailed field seismic surveys with thickened, not more than 100 m grid of seismic profiles, perform the processing of the field of seismic data reveal the presence of an anticlinal structures and deep faults, build seismo-geological profiles along and across the identified structures, determine the depth of castles folds, morphological parameters of structures, installed according KAB=f(N) determine the values of total porosity in the depth of the horizon on the newly identified structures, determine the predictive value of the gradient of the pore pressure and at a set of multidimensional correlation of secondary porosity Qpvt=f(i,gradp,J,PBC,M) forecast value KPVT, compare it with the lower limit KVTCRfor the border collector - collector", and then predict the probability of development of secondary collectors fracture type, the feasibility of production drilling on these structures and the order of the input wells to drill, and when the compared KPVT/KVT CR>1,2 - appropriate drilling profile of the three dependent wells; with respect KPVT/KVTCR=(0,7÷4,2) - drilling only one well in the arch structure.
The invention is illustrated in the drawing, in which figure 1 shows the change in the porosity of the upper Cretaceous limestones (KP) from depth (M) and gradient formation pressure (cipher curves) along areas:
1 - Karabulak-Achalukskaya; 2 - Zamankulskoye; 3 - Malgobek Ascension, Arak-Galatarasay; 4 - Jan-Kostovska, Eldarovskaya; 5 - Gorjacheistochnenskaja, Starogroznenskaya, Gudermes, Mineral, Braguinsky, October; 6 - North-Mineral, Chervlennaya, Right Bank; 7 - St. Andrew, North Starogroznenskaya, Maghrebia; 8 - Anouska.
A method for predicting development zones secondary reservoir fracture type in the sedimentary cover is as follows.
Each oil and gas area in the first phase of exploration, as a rule, in the first place are identified and entered into the exploration of large-size structures, later in the exploration introduces patterns significantly smaller, which do not always have effective traps for hydrocarbon accumulations. In this regard, in the final stages of exploration is important to determine quantitative criteria, allowing to assess the feasibility of entering into the exploration of new the x little amplitude anticlinal structures. This primarily is determined by the presence or absence of potential reservoirs with secondary (fracture) porosity and flow of these hydrocarbons. According to current theoretical ideas about the mechanism of formation of fractured reservoirs on the value of the secondary (fracture) porosity in carbonate strata importantly influenced by the following factors: the strength properties of rocks, morphology folds and pressure, and the flow of hydrocarbons into the reservoir as possible at the expense of pushups them from above or underlying tires, and due to the influx of more depth by deep faults.
To achieve this goal through the old Fund drilled structures determine the depth of the castles of folds (N), morphological parameters of the structures, including the maximum bending of the layers (i), width (M)length (L), area (S), the intensity of folding (J=i/S). According to the results of geophysical investigations of wells during drilling of these structures define values total (Kpob) and secondary (Cpvt) poristosti determine reservoir pressure in the intervals tested. Build the dependence of the total porosity and the depth of layers KAB=f(N). Comparing the average value of the secondary porosity (Cpvt) with the 1 m interval test rate of flow of formation f is wide establish the critical value of the secondary porosity (Cpvt CRfor border collector-collector", which almost has not been obtained hydrocarbon flows. By multiple correlation reveals the dependence of the secondary (fracture) KPVT porosity depths of the castle (N), the amplitude and the linear dimensions of structures, reservoir pressure and block porosity, on the basis of which we can predict secondary porosity on the newly identified structures, the ratio of which to the critical value of the secondary porosity is judged on the presence of an effective trap, the feasibility of production drilling on the structure and order of input wells in drilling, with respect KPVT/KVTCR>1,2 -, it is advisable to plan the drilling profile of the three dependent wells; with respect KPVT/KVTCR=(0,7÷1,2) - to plan drilling only one well in the arch structure; with respect KPVT/KVTCR<0,7 - drilling inappropriate conduct.
On unexplored method of seismic stations territories or studied with sparse grid of seismic profiles, conduct detailed field seismic surveys with thickened through a 100 m grid of seismic profiles, perform the processing of the field of seismic data reveal the presence of an anticlinal structures and deep faults, build seismo-geological profiles along, and p is the par of the identified structures, determine the depth of the castles of folds (N), morphological parameters of the structures, including the maximum bending of the layers (i), width (M)length (L), area (S), the intensity of folding (J=i/S). Prescribed based KAB=f(N) define values total (Kpob) porosity at the depth of the horizon on the newly identified structures, determine the predictive value of the reservoir pressure gradient (gradp) and installed multidimensional correlation of secondary porosity Qpvt=f(i, gradp,J,PBC,M) forecast value KPVT, which is then compared with the lower limit KVTCRfor the border collector - collector". According to the obtained results is judged on the presence of an effective trap, the feasibility of production drilling on the structure and order of input wells in drilling, with respect KPVT/KVTCR>1,2 -, it is advisable to plan the drilling profile of the three dependent wells; with respect KPVT/KVTCR=(0,7÷1,2) - to plan drilling only one well in the arch structure; with respect KPVT/KVTCR<0,7 - drilling inappropriate conduct.
The method is industrially applicable. The practical implementation of the method carried out on the example of upper Cretaceous deposits of the Terek-Sunzha oil field in Eastern Ciscaucasia, within which for the period 196, revealed and brought into development at the depth of 2000 m to 5500 m many oil and gas fields. To predict the availability of effective traps with fractured collector on the new not yet drilled anticlinal structures we use the method of multiple correlation. For this to 15 identified by the method of seismic and drilled anticlinal structures were determined depth castles of folds (N), morphological parameters of the structures, including the maximum bending of the layers (i), width (M)length (L), area (S), the intensity of folding (J=i/S). According to the results of geophysical investigations of wells during drilling of these structures have been calculated values total (Kpob) porosity by NTC and secondary (Cpvt) porosity, built dependence KAB=f(N), defined gradients, formation pressures in the intervals tested. Comparing the average value of the secondary porosity (Cpvt) with the 1 m interval test rate of flow of formation fluids, set the critical value of the secondary porosity (CpvtCR=0,2%), which almost has not been obtained hydrocarbon flows.
The method of multiple correlation using information on 15 structures derived a regression equation with a correlation coefficient of 0.85 relating the amount of secondary porosity simultaneously with all parameters: KVT=2,3·10-4i+0,895·gradp+2,5·10-2J -2,58·10-2Kob is 6.67·10-2 N-0,945, (1) where i is the maximum bending of layers, m; gradp - gradient reservoir pressure, MPa/m; J=i/S is the intensity of folding, m/km2(S - structure square, km); Kob - total porosity at the depth of the forecast %; H - depth of the upper Cretaceous carbonate strata, km
The values of correlation coefficients of the linear relationship (r) between the secondary porosity (Cpvt) and other values, as well as between each pair of the analyzed parameters are presented in table 1. As you can see, we have proved the existence of a statistical pairwise relations between parameters, but found that the closeness of the pair of links is low.
From table 1 it is evident that none of the options when paired correlated with each other does not give a linear correlation coefficient, which would exceed the absolute value of 0.85.
In nature, the amount of secondary porosity at the same time is influenced by various factors, therefore, to increase reliability of estimates of secondary porosity by method of the many the military correlation equations of, connecting the value of secondary porosity with two or more parameters, which are given below in table 2. It is seen that with the increasing complexity increases the correlation coefficient, i.e. the reliability of determining Cpvt. Therefore, to predict values of secondary porosity in the exploration areas are encouraged to use the regression equation (2-5).
|The form of equations||The coefficient of multiple correlation|
|Qpvt=0,04736J-0,20801H+0,10406gradp+0,70626 (3)||coefficient was 0.796|
Types of equations based Cpvt from morphological structure parameters and the values of the coefficients of multiple correlation.
Regression curves were made using the method of least squares by step-by-step linear regression, when at each step of the entire set of arguments stood out the one that had the most significant in Janie on the magnitude of the correlation relationships multiple correlation coefficient (R), are presented in table 3.
Simultaneous examination of tables 1 and 3 shows that the absolute values of partial correlation coefficients (r) less than the value of the coefficient of multiple correlation (R).
Thus, for example, the upper Cretaceous deposits of the Terek-Sunzha oil field analyzed, what value have on the amount of secondary porosity, the degree of bending of the layers, the depth of the rock, i.e. the total pressure, the strength properties of rocks associated with the block porosity.
This method was previously tested on the 15 studied by drilling structures of the Terek-Sunzha oil and gas field, on materials which were calculated regression equations. Calculated by the formulas (2-5) values secondary porosity were compared with the values of the HTP, approved by GKZ in the calculation of reserves. From table 4 it is seen that they are well matched. Deviation is not more than ±20%. To predict the availability of effective traps with fractured collector of newly diagnosed anticlinal structures by seismic data was determined depth castles, amplitude, linear dimensions of the structures and the presence of deep faults. According to the schedule KAB=f(N) (figure 1) was determined by the total porosity and reservoir pressure gradient and by the formulas (2-5) multiple correlation was calculated forecasted value KPVT, which was compared with the value KVTCR. According to obtained results were judged on the presence of the collector and effective traps, and feasibility of production drilling on the identified structure. To test the effectiveness of the proposed method was carried out on the example of several structures, which were in the early stages of exploration, or have not yet been entered in the survey and were not used in the sample data to obtain the source dependencies. The result of the forecast values of secondary porosity are given in table 5. Detailed analysis of the data in the table by the squares at the initial stage of exploration, showed the following:
1. Identified methods of seismic exploration on the roof of the upper Cretaceous carbonate deposits Andreyev raising has an area of 42 km 2bending of the layers of 500 m, the intensity of folding 11,76 m/km2. The depth of the lock structure of 5.6 km on Certain graphs KAB=f(N), and gradp=f(N) predictive values were: total porosity Kbob=1.6%, and gradient formation pressure of 1.44·10-2MPa/m In the upper Cretaceous sediments of the St. Andrew's square, the predictive value of secondary porosity by the formula (1) is 0.22%, calculated according to the materials of geophysical research Cpvt in well # 1 drilled on the crest of the structure, is also equal to 0.22%. As for the upper Cretaceous deposits KVTCR=0,2%, the ratio KPVT/KVTCR=1,1. At test well No. 1 received the oil flow with a rate of 84 tons/day in 4 mm socket.
2. North Starogroznenskaya structure according to the seismic work has the following morphological parameters: the area of 33 km2bending of the layers 220 m, the intensity of folding 6,67 m/km2the depth of the lock structure 5,5 km Forecast parameters were: total porosity Kob - 1,6%, gradient formation pressure of 1.42·10-2MPa/m, secondary porosity is calculated by the formula (1) multiple correlation is 0.06%. On the structure were two wells were drilled. The weighted average value of the secondary porosity throughout dissected power of the upper Cretaceous materials of GIS in the well the No. 1 and No. 2 is 0.11%. Thus, the forecast (0,06%) and actual (0,11%) of the secondary porosity near and below the critical value, i.e. KPVT/KVTCR=(0,06-0,11)%/0,2%=(0,3-0,55)<0,7, indicating the absence of an effective collector. When testing these wells were obtained weak tributaries of the reservoir water with a fading rate (1,5÷6) m3/day, which confirms the absence of a header.
3. Alkhanchurtovskiy structure revealed by seismic, has an area of each holding 21.25 km2bending of the layers 50 m, the intensity of the folding - 2.35 m/km2, the predictive value of the gradient of the reservoir pressure is 1.4·10-2MPa/m, the total porosity is-1.8%. The depth of the lock structure of 4.66 km Prognostic significance of secondary porosity in the crest of the structure is equal to 0.02%, which is significantly less than the critical value of 0.2%, i.e KPVT/KVTCR=0,1<0,7 that indicates the futility of the section from the point of view of the reservoir. According to the materials of GIS in well # 1 drilled on the crest of the structure, the incision is characterized as dense, and when tested by the method of IPT during drilling of the upper Cretaceous deposits of the inflow is not received.
4. Tests in the well area of the North-Braguinsky where the inflow of formation water 10 m3/s, does not contradict the fact that in the sections of the drilled wells are collector with secondary porosity > 0.2 percent. rognone the value of the secondary porosity is equal to 0.34%.
5. The weighted average value of the secondary porosity of the materials on GIS Olowski square is equal to 0.51 percent, the forecast value is 0.31%. When testing the obtained oil flows with flow rate up to 120 t/day in 4 mm socket.
Thus, it is seen that the secondary porosity is calculated by the formula (2-5), confirmed by geophysical investigations and testing.
Similarly, the calculations of secondary porosity (table 5) and assessed the viability of a number of other anticlinal structures identified by the method of seismic exploration, the results of which, together with recommendations submitted to the JSC "Rosneftegaz". From a consideration of the structures for which the calculated predicted values of secondary porosity, it is clear that the most promising from the point of view of the reservoir are the upper Cretaceous deposits of squares Satanovsky, Meskhetinsky, North Benaissa, where the forecast value of the secondary porosity is equal to 0.75% and more.
In the arched parts of the structures Belorechenskaya, East Gudermes, Novolakski Boundary, Olowska, Peter and Paul, South of the right Bank, North Braguinsky, Herstynska assumes the presence of reservoirs with secondary porosity of 0.5%. Patterns of Nozhay-Yurt, Koshkeldinskaya, North Khankala, Galchinsky, North Galchinsky, Chapaevsk, Arkabarka, the Andes is eisca, Arak-Galtarossa, Pradhananga, Jaruzynska, North Zamankulskoye, North Pacanowska, South Han-Kostovska, South Peter and Paul also are promising from the point of view of the reservoir. The forecasted values Cpvt them reach of 0.25%. According to estimates of secondary porosity in the squares East Khankala, Sandusky, North Eldarovskaya, Alkhanchurtovskiy, Maghrebia, Forest, Grape, Roadside, Grozny, South Khankala is below the lower limit of 0.2%, i.e. accumulations of hydrocarbons must not be present,and these areas are not promising for deep exploration drilling.
Thus, the described examples confirm the possibility of prediction of secondary porosity in the new structures and the feasibility of the proposed method for predicting reservoir with secondary porosity and effective traps in carbonate sections. The method can also be used to search for deep-seated reservoirs with secondary porosity terrigenous sequences, not promising for searches deposits in reservoirs granular type.
The economic efficiency of the proposed method is to reduce the costs of exploration of oil and gas fields in deep reservoirs with secondary porosity by-founded the project for the feasibility of production drilling on identified methods of seismic low-amplitude anticlinal structures and order of input wells in drilling.
A method for predicting development zones secondary reservoir fracture type in the sedimentary cover, including the processing of reflected seismic waves, linked to a selected range of sediments, taking into account data of geological and geophysical surveys in wells, conducting lithologic-petrographic studies of rock samples to determine the most probable Genesis of secondary collectors, the selection of lithotypes, which is the formation of secondary collectors fracture type, characterized in that the drilled anticlinal structures determine the depth of castles folds, morphological parameters of the structures, including the maximum bending of the layers, width, length, area, intensity of folding, the results of geophysical investigations of wells when drilling these structures determine the values of secondary porosity, measured reservoir pressure at intervals of tests, establish the critical value of the secondary porosity - KVTCRset of multidimensional correlation of secondary porosity by the formula Qpvt=a·i+b·gradp+c·J+d·Kob+f·H, where i is the maximum bending of the layers, gradp - reservoir pressure gradient, J=i/S is the intensity of folding, S - the area of patterns, P, the b - the total porosity, H is the depth of the castle folds; a, b, C, d, f are coefficients of proportionality defined for a specific region, then unexplored areas conduct detailed field seismic surveys with thickened through no more than 100 m grid of seismic profiles, perform the processing of the field of seismic data reveal the presence of an anticlinal structures and deep faults, build seismo-geological profiles along and across the identified structures, determine the depth of castles folds, morphological parameters of structures, installed according KAB=f(N) determine the values of total porosity at depth horizon on the newly identified structures, determine the predictive value of the gradient of the pore pressure and at a set of multidimensional correlation of secondary porosity Qpvt=f(i, gradp, J, KAB, H) predict the value of Cpvt, compare it with the lower limit KVTCRfor the border collector-collector", and then predict the probability of development of secondary collectors fracture type, the feasibility of production drilling on these structures and the order of the input wells in drilling, with respect KPVT/KVTCR>1,2 appropriate drilling profile of the three dependent wells, with respect KPVT/KVTCR=(0,7÷1,2) - b is drilling only one well in the arch structure.
SUBSTANCE: invention refers to the methods of detecting the forerunners and can be used to identify the possibility of earthquakes in the Baikal Lake region. The invention concept is as follows: water samples are taken from the zone of intersection of deep breaks in the Baikal Lake territory where earthquakes of different intensity took place repeatedly. Sampling is performed by a water intake structure comprising a deepwater intake (8), an electric pump (9) set at the water intake station on the Baikal bank, filters for coarse (10) and fine (11) treatment of water. Concentration of helium dissolved in the deep water is examined. A conclusion on possible earthquake is made on the basis of the curves of the helium concentration variation.
EFFECT: detection of a possibility that an earthquake will occur.
2 cl, 4 dwg
FIELD: physics; geophysics.
SUBSTANCE: invention relates to geoexploration and can be used to determine different properties of hydrocarbon formation fluids. The invention discloses examples of methods, apparatus and articles of manufacture for process measurements of strings vibrating in fluids. A disclosed example of an apparatus includes a downhole assembly and a surface assembly. The downhole assembly 300 includes a sensor 305, 325 for measuring a waveform representative of a motion of a string vibrating in a fluid at a downhole location in a wellbore, a waveform simulator 332 for computing a model parameter based on the measured waveform, and a first telemetry module 340 for transmitting the computed model parameter to a surface location. The surface assembly includes a second telemetry module for receiving the computed model parameter from the downhole assembly, and a viscosity analyser for estimating a viscosity of the fluid based on the computed model parameter. The method of processing measurements of strings vibrating in a fluid involves an operation for measuring a waveform and computing a model parameter of vibration of the string based on the measured waveform. Said model parameter is used to determine viscosity of the formation fluid.
EFFECT: high accuracy of determining properties of formation fluids.
32 cl, 7 dwg
SUBSTANCE: invention relates to surveying and geodetic monitoring and can be used to ensure safety of oil and gas field exploration. As per the proposed method the geodetic measurements are carried out in the examined area and displacements Ngeod of geodetic becnhmarks to the north
EFFECT: higher accuracy of determination of earth surface displacement.
FIELD: oil and gas industry.
SUBSTANCE: based on structural maps and seismic profiles, by earlier seismic exploration researches within the earlier studied sites of oil-and-gas province, stratigraphic interval down the geological section is determined, by which satisfactory spatial correspondence of day surface morphology to morphology of paleorelief lithostratigraphic (seismostratigraphic) horizons is clearly observed. Topographic maps of all scales from 1:25000 to 1:1000000 and in the same scales a plan of earlier found deposits (if any) throughout the whole territory of intended works are scanned. Study territory is sorted by topographic maps into sites by the degree of relative compartmentalisation of relief that is expressed by the width of watershed areas, which basically define day surface morphosculpture. At that, the width of watershed areas measured by many tens of kilometres and even over one hundred kilometres indicates prospectiveness of a site for search of giant and large hydrocarbon deposits. Sites, within which the width of watershed areas is characterised by values to the first tens of kilometres, are prospective for detection of mainly small and medium hydrocarbon deposits. Study territory is sorted into sites by relative relief height. At that, sites with relatively big relief height indicate relatively large surface relief amplitude by underlying lithostratigraphic units, which imply probability of discovery of hydrocarbon deposits with higher amplitude. Based on the results of territory sorting by indicated parameters, sites are identified prospective for discovery of giant, large, medium and small hydrocarbon deposits. A site is selected based on the results of conducted analysis, meeting the solving tasks, within which forecast and further search of corresponding hydrocarbon deposits will be carried out by topographic maps in scale of 1:25000. Values of long and short axes of earlier detected hydrocarbon deposits and values of their sums for each deposit are measured. Plans in scale of 1:25000 of all earlier detected hydrocarbon deposits within the studied oil-and-gas province, region or district are matched with a topographic map in the same scale in order to find out the degree of correspondence in the plan of contours of detected deposits with the contours of local positive forms of present relief. Based on the results of this match, earlier detected hydrocarbon deposits are sorted into three groups: deposits, which contours' position on the plan almost exactly matches the contour of their corresponding local positive forms of relief; deposits, which plan position is displaced to the distance not exceeding the half of the value of a corresponding linear dimension of day surface local positive form; and deposits, which plan position is displaced to the distance exceeding the value of a corresponding linear dimension of day surface local positive form. For each deposit of the last group, values of the sum of their linear dimensions are found; at that, maximum value of the sum of linear dimensions of a deposit is determined as "critical". A conclusion is made that for deposits, which value of the sum of their linear dimensions meets or below the critical value, forecast reliability by this method within the given territory is not enough. By topographic map, day surface local positive forms with a value of the sum of linear dimensions exceeding the critical value are detected. A conclusion is made that these local positive forms of day surface on the plan by regionally productive sediments are matched by about the same hydrocarbon deposits by linear dimensions, orientation and configuration. Area of forecast deposits is measures and values of forecast hydrocarbon resources in them are determined by set for each oil-and-gas province empirical dependence between deposits area and their reserves. Based on dimensions, configuration and orientation of short and long axes of detected positive forms of present relief, all parameters of search seismic profiles network are designed. At that, for giant and large anticlinal traps, dimension of seismic profiles parallel to the trap's long axis must make double dimension of the long axis of positive relief form, and dimension of seismic profiles parallel to the trap's short axis must make triple dimension of the short axis of positive relief form. For medium and small traps, dimension of seismic profiles parallel to the trap's long axis must make triple dimension of the long axis of positive relief form, and dimension of seismic profiles parallel to the trap's short axis must make five-times dimension of the short axis of positive relief form. At that, one part of seismic profiles is to be designed perpendicular to the short axis of a forecast deposit, and the other one perpendicular to its long axis. By designed network of seismic profiles, seismic surveillance is carried out for each of forecast hydrocarbon deposits. Structural maps are created by target reflecting horizons, based on which exploration wells are recommended and staked.
EFFECT: increased forecast reliability, decreased scope of prospecting works.
FIELD: measurement equipment.
SUBSTANCE: invention relates to the field of seismology and may be used to forecast possibility of earthquakes within collision zones of continents. Substance: on the basis of monitoring of many years they determine content of the following pollutants in the near-surface atmosphere: dust, carbon, nitrogen and sulphur oxides. If the annual summary content of the specified pollutants increases in the near-surface atmosphere by more than 20% compared to the average annual value produced during the period of the completed monitoring, the conclusion is made on the possibility of earthquake occurrence.
EFFECT: forecasting of possibility of earthquakes within collision zones of continents.
SUBSTANCE: air samples from topsoil at selected locations of analysed territory. Taken samples are analysed to define radon volumetric activity. Mean arithmetic radon volumetric activity is used to delineate the fault abnormalities. Spatial and quantitative relationships between radon abnormality and fault fissuring fields are calculated. Now, fault radon activity indicator is estimated along with fault dynamic influence zone width at section under analysis.
EFFECT: higher validity.
FIELD: measurement equipment.
SUBSTANCE: thermal probe is proposed for measurement of vertical distribution of water temperature, comprising a body that represents a stiff structure, equipped with a stabiliser and placed in a cassette, equipped with a mechanism of partitioning with a thermal probe body. Inside the thermal probe body there are two primary temperature converters, two measuring generators, communication lines, two filters, two converters of frequency-voltage and a recorder, and also a sensor of depth, a sensor of electric conductivity and a flow meter. The body in the lower part is equipped with an anchor weight with a hydroacoustic disconnector and a transceiving antenna of the hydroacoustic communication channel. In the upper part of the thermal probe body there is an antenna of a radio transmitter of a satellite communication radio channel, which is placed inside the body of the thermal probe.
EFFECT: expansion of functional capabilities of a device.
FIELD: oil and gas industry.
SUBSTANCE: invention relates to well surveying and can be used for continuous monitoring of parameters in the well. The invention suggests the system of supervision that includes sensors, in particular, pressure and temperature sensors, a cable connecting the supervision system and the well head. At that the well head contains an electric terminal with a telemetric system for data acquisition and a power source for the well supervision system. Besides the electric terminal of the well head contains a command module for the well supervision system and a data storage module with a microprocessor.
EFFECT: simplifying the system for monitoring parameters in the well.
24 cl, 4 dwg
FIELD: oil and gas industry.
SUBSTANCE: invention relates to the field of searches of hydrocarbon deposits. The invention concept is as follows: a number of holes is drilled up to the depth of 1-3 m. Samples of gaseous medium are taken by bubbling through mineralized water and hydrocarbon gases are analysed. Besides, air-gas mixture inside holes is analysed for presence of helium, radon, hydrogen, nitrogen, carbon dioxide and oxygen dioxide. The area with the most favourable content of helium, radon, nitrogen, carbon dioxide, oxygen dioxide, and hydrocarbon gases is referred to oil and gas deposits.
EFFECT: implementing search of hydrocarbons.
FIELD: measuring equipment.
SUBSTANCE: invention belongs to methods of quantitative assessment of natural processes and can be used for definition of a mass consumption of water vapour on volcanoes. Substance: on a visible site of a steam loop of a volcano they measure its cross-section, speed of a flow and temperature. In ambient air they measure humidity, temperature and atmospheric pressure. Using measured dimensions, they count air undersaturation at temperature of a steam loop. Using values of air undersaturaton, they count mass consumption of water vapour.
EFFECT: decrease in labour costs at definition of mass consumption of water vapour on volcanoes.
SUBSTANCE: group of inventions refers to method and device for control and correction of time settings used in a distributed nodal seismic receiving system. So a wireless seismic data recording unit is fitted by a wireless receiver providing access to the common external time standard shared by the variety of seismic data recording units in a seismic system. The receiver is made able of replicating the local version of the external time reference point with which an analog-to-digital converter of a seismic sensor is synchronised. The receiver is made able of replicating the local version of the common external time standard to put time marks on local events of the node. The receiver can be switched into nonoperating mode with low power consumption for the time periods when the seismic data recording unit continues to record the seismic data, thus battery supplied power is preserved. The system implements the method for local clock correction basing on the intermittent access to the common external time standard. The method provides for the correction of local time at the clock with the help of a voltage controlled clock generator to consider the time errors caused by the environment conditions. Additionally the invention provides for more reliable method to correct drift of the local clock.
EFFECT: minimisation of power consumption, improved accuracy of data acquisition.
33 cl, 7 dwg
FIELD: physics; geophysics.
SUBSTANCE: invention relates to devices for seismic exploration of hydrocarbon deposits on the water area of the arctic shelf. The mobile self-contained underwater seismic-hydroacoustic station for exploration of hydrocarbons on the water area of the arctic shelf has a hard, streamlined housing, a power plant, a motor, a gyroscope, a distance measuring device, an echo sounder, a depth sensor, a hydroacoustic beacon signal locator, buoyancy control means and an on-board computer with a program device for controlling movement of the station from one point on the sea to another, hovering, sinking to the bottom, raising from the bottom to a given depth and onto the sea surface.
EFFECT: designing a mobile underwater self-contained seismic-hydroacoustic station for exploration of hydrocarbons, capable of independently moving according to a given program to investigated points on the sea, hovering over said points, sinking to the bottom and raising from the bottom to a given depth while simultaneously reducing self-generated seismic-hydroacoustic noise.
SUBSTANCE: method involves excitation of elastic vibrations by a vibration source in a well crossing hydraulic fracturing cracks, recording at receiving points at least in one neighbouring well of resonant vibrations emitted with a hydraulic fracturing crack system at excitation in drilling fluid of elastic vibrations, and determination of parameters of the crack system as per resonant vibrations occurring in the cracks. Excitation of vibrations in the well and their recording is performed before and after hydraulic fracturing. Besides, for each fixed source-receiver pair there formed is a difference seismic record of the records received before and after hydraulic fracturing; signals emitted by the crack system are separated on the difference seismic record, and parameters of cracks are determined as per the above signals.
EFFECT: improving reliable determination of spatial orientation of a hydraulic fracturing crack system and its dimensions.
SUBSTANCE: group of inventions includes a method of extracting hydrocarbons from a subsurface region, a method of transforming seismic data paths and a method of determining a near-surface earth model of elastic shear wave propagation velocity based on the seismic data path. The invention employs seismic data, recorded preferably with a plurality of sources and receivers and a two-stage inversion technique. First, variations in surface-wave signals are decomposed (303) into surface-consistent transfer functions, preferably for each source, each receiver and each small region (301) of the surface. The transfer functions for each region are then inverted (308) to determine soil properties or near-surface properties (such as the shear modulus) as a function of depth. The method can solve for the complex multi-mode nature of the surface waves for media with vertical and lateral changes in properties.
EFFECT: avoiding errors and limits in resolution for traditional methods from misidentification of ground roll modes or from assuming laterally uniform soil properties, obtaining elastic soil properties, obtaining elastic properties as a function of depth from surface or depth profile of properties.
22 cl, 15 dwg
FIELD: oil and gas industry.
SUBSTANCE: seismic measurements are carried out by means of a CDP method on the surface area perspective in oil-and-gas-bearing respect. Processing and structural interpretation of seismic data is performed, thus obtaining structural maps of target reflecting horizons. Based on structural maps, additional build-up of two-dimensional networks of target reflecting horizons is performed. As per the received two-dimensional networks of target reflecting horizons and using a trend analysis method, build-up of two-dimensional networks a regional component is performed for each reflecting horizon. A local component is calculated. For cells of the two-dimensional network of the local component the prepared structures are localised for each target reflecting horizon at simultaneous fulfilment of two conditions: first - when the local component is larger than zero, and second - when a zero contour is closed. A sum of local component is defined for all the target reflecting horizons. With that, the local structure is considered to have been prepared for all the target reflecting horizons when the value of sum of local component is larger than zero. For allocated localised structures for each reflecting horizon there calculated is local structure amplitude and local structure surface area. Priority of readiness degree of the structure prepared for prospecting and exploratory oil and gas drilling is determined as per the value of amplitude and surface area of local structure, and namely: the higher the above local structure values, the higher the perspective of prospecting and exploratory oil and gas drilling.
EFFECT: improving geological informativity of geophysical surveys, localisation and ranging of prepared structures as to the perspective at preparation for prospecting and exploratory drilling.
FIELD: radio engineering, communication.
SUBSTANCE: disclosed is a method of detecting voids in the upper section of the earth's crust, involving measurement and detection of acoustic emission on the profile in the 0.01-500 Hz frequency range, with distance between measurement points in accordance with survey scale. Profiling is performed based on natural acoustic noise. Acoustic emission is detected at each point for at least 1 minute; acoustic emission spectra are calculated in 3-10 s in multiple time intervals; the average dominant experimental spectrum Se(f) and the mean-square deviation (σs) of the average from the three-second spectra are found. The theoretical shape of the desired objects is set and theoretical spectra S0(f) thereof are calculated. Resonance frequencies fm are determined from the function Se(f); curves of intensity of the spectral function Se at resonance frequencies fm (m=1, 2, 3) are plotted. Probable boundaries of desired objects on the profile are determined from intensity anomalies indicated by intensity of the spectral function S(fm) on the profile exceeding its average value by +Kσ, and gradients of the function S(fm). Preliminary dimensions and shape of said objects are determined from said boundaries and the given shape. Theoretical spectra are calculated, compared with experimental spectra; the most similar theoretical spectrum is found from the mean-square difference which does not exceed +Kσs (K=1-3) and the selected theoretical spectrum is identified with voids of a given shape and size.
EFFECT: detecting voids without breaching the integrity of the earth's surface.
SUBSTANCE: method involves performing geologic and seismic survey, as well as remote optical gas analysis using remote lidar. During gas analysis, a spectral image of the set of chemical components in the surface layer of the atmosphere is formed. Spatial selection of the spectral image of the area on given tracer substances is performed. The detected gas components are compared with the composition of the reference mixture of hydrocarbon components which corresponds to the geographical position of the area and the deposit. The area is mapped with spatial differentiation on the relief of the obtained spectral image of the probed area. The spectral image of the region of the authentic hydrocarbon deposit is selected on the map. A family of points with the measured concentration of heavy hydrocarbons is determined.
EFFECT: high accuracy of searching for hydrocarbons, low cost of search operations.
SUBSTANCE: according to the disclosed method, observation lines during land seismic survey have to be given on straight sections of the projection of a curvilinear well bore on the day surface.
EFFECT: high accuracy of determining the structural form of geological objects and longer tracking thereof during combined interpretation of well and land seismic survey data.
SUBSTANCE: group of inventions discloses an apparatus, system and method for seismic investigation of an underground structure by displaying seismic image data, which involves calculating, based on a set of wide azimuth data, a set of discrete data associated with an image function at a point of the seismic image. The set of discrete data can be transformed into a continuous curvilinear three-dimensional surface. The displayed set of data can be projected on a continuous flat surface. The projected data can be displayed in form of a flat disc. A plurality of continuous flat surfaces, each representing a single point of the image, can be collected to form a three-dimensional body which is a seismogram of points of the image. The three-dimensional body can be displayed.
EFFECT: high accuracy of geophysical detection during survey and extraction of oil and gas.
25 cl, 9 dwg
SUBSTANCE: seismic exploration system includes a seismic vibrator capable of exciting signals of different spectral composition with a system for generating control signals and a system for controlling the excited probing signals, a seismic station capable of correlating vibration records and converting the vibration records to impulse seismograms with a system for generating correlation signals and a system for determining parameters of control signals and means of communication between the seismic station (seismic vibrator) and the seismic vibrator (seismic station). The output of the system for controlling excited probing signals is connected through the means of communication between the seismic vibrator and the seismic station to the input of the system for generating correlation signals. The output of the system for determining parameters of control signals is connected through the means of communication between the seismic station and the seismic vibrator to the input of the system for generating control signals.
EFFECT: high accuracy and information value of seismic exploration.
FIELD: seismic prospecting.
SUBSTANCE: method can be applied at prospecting of oil and gas pools as in sedimentary and in metamorphic and crystal rocks. Seismic waves induced by seismic standard source close to surface are registered. Wave fields are formed from expected objects of reflection, diffraction and dissipation and parameters of processing are chosen in such a manner to provide better selection of modeled objects on the error background. Received parameters are used for processing real data and selecting real objects. Shapes of objects of dissipation are presented in form of maps and sectional views.
EFFECT: increased level of valid signal.