Oil deposit extraction method

FIELD: oil and gas extractive industry.

SUBSTANCE: method includes construction of wells and oil and gas collection system, forcing water from water-bearing level into oil deposits, flow of oil from oil deposits into secondary deposit and following extraction of oil from secondary deposit for useful implementation. Resources of deposit are separated on basis of natural energy characteristic on screened and having rigid water-forcing mode. Deposit is operated by three well types. Of the latter flow wells connect oil deposits to secondary deposit for flowing and collection of oil in upper bed under effect from gravitation. Balancing wells connect screened deposits and secondary deposit to water-forcing level for balancing of bed pressures and preventing loss of rocks stability. Extraction wells connect secondary deposit to oil and gas collection system. Selection of bed for secondary deposit is performed from number of highly penetrable beds, having maximally allowed excess over oil deposits.

EFFECT: higher oil yield, higher effectiveness.

5 cl, 3 dwg

The invention relates to the oil and gas industry and can be used to develop oil and gas fields in complicated geologic conditions for extraction of residual oil from the reservoirs produced with known methods, for oil, to prevent environmental threats of pollution by hydrocarbons upper aquifers and the atmosphere and to prevent man-made disasters.

In practice widely used method of oil field development with the construction of production wells through which the oil is withdrawn from the reservoir for beneficial use. Wells and deposits cease to operate when the limit is reached profitability, i.e. when the unit cost of oil production is equal to the selling price.

The disadvantages of this method are the high cost of oil production and low productivity oil reservoirs, at great depths and in difficult terrain. Because of the high cost of production discovered or are not entered in the design, or cease to operate at low ratios of oil recovery, and this leads to irretrievable loss of oil, creates global threat of contamination of the upper aquifer and atmospheric oil and gas [Zh is an RF ″ Geoecology", 2000, No. 4, s-333] due to the spontaneous overflow of their deposits through the drilled hole. If the operation field is accompanied by a significant drop in pressure in the deposits, it can cause subsidence of land surface and earthquakes due to buckling insulating deposits of rocks.

These drawbacks are partially eliminated in the known way of developing multilayer oil field [U.S. Pat. Of the Russian Federation No. 2003785, MKI E 21 In 43/020, publ. 1993], which includes the construction of producing, injection, intake and one Central hole, an oil flow from the oil deposits in artificial secondary reservoir and petroleum reservoirs in sequence from the bottom up.

The disadvantages of this method are the large material costs for mine development, large residual oil in the reservoir, not reliable prevention of environmental hazards and limited scope.

Large capital costs for implementing the known method is caused by the necessity of building a large number of different wells, high costs for their conversion during the development of the field. Particularly expensive is the Central well because of its large diameter and cementing operational Colo who are only in the range above the secondary deposits. Large capital expenditures are also required on the field due to the need for laying of flowlines from wells Central wells. In addition, large capital costs requires equipping wells pumps and the construction of surface water treatment plants, without which the vast majority of conditions, the injection of water into oil reservoirs is impossible. High operating costs due to the need of the use of pumps as for the selection of water-cut oil from the reservoir production wells and water injection. High costs are also required to prepare water-cut oil, for cleaning and recycling or disposal of the separated produced water, to prepare and injected into the reservoirs of underground water. Through the development of oil deposits of the Central bore after returning wells to Vistalegre horizon will increase the ultimate oil recovery factor, but by a small amount. This is due to the fact that the Central bore is located at a large distance from the injection wells and in the face of declining consumption, injection water to achieve efficient oil displacement in the direction of the Central bore impossible. In addition, I agree occurrence of productive strata exact codes on Vert the local section is extremely rare. In most geological conditions while drilling the Central hole in the vault of one of the deposits stacked field, its position in terms relative to other deposits should be expected on the wings of the structure up to a position beyond the path of oil. Therefore, a substantial increase oil recovery from the field redevelopment of the Central bore can be expected only one deposits, by putting it in the vault. In other deposits of oil will accumulate mainly in domes structures, because of the reduction in the rate of artificial flooding will begin to dominate the gravitational vertical displacement of the movable residual oil towards the top of the reservoir, the displacement efficiency along the layering direction to the Central well is low. Large remaining reserves of the movable oil deposits create preconditions for flow of this oil by collapsing producing wells in the upper aquifer and in the atmosphere [Journal of the Russian Academy of Sciences "Geoecology", 2000, No. 4, s-333]. The disadvantages of this method include also unsustainable costs of water injection in oil fields: in cases when deposits are characterized by hard water regime, pumping water into them is not required. Due to the above reduction of the effectiveness of this method when dissenting taleghani the productive layers decreases the area of its application. This area is further reduced due to the use of the method only on multilayer fields. In the prototype is not specified and does not discuss the possibility of using the method in the presence of unproductive and not used for the formation of secondary deposits of water layers between developing oil deposits, issues of attachment of the open trunk of the Central hole to prevent caving of the walls, and under the action of any forces from the Central well drained produced water coming into the well along with oil after water flooding deposits. The absence of such data makes it difficult to estimate the number stated advantages of the known method, and a marked characteristic of maintaining the level of oil-water partition at the mouth of the Central bore prevents an oil flow in the secondary reservoir and the implementation method for the following reasons. The initial pressure in productive and non-productive formations in most of the oil fields equal to the pressure of the pillars of fresh or brackish water, a height equal to the depth of the layer, i.e, for example, at a depth of 1000 m, the pressure is about 10 MPa. So after filling the wells with highly mineralized water from the oil reservoir pressure at the bottom hole will be above the initial reservoir, the inflow into the well of oil from the reservoir will be impossible. If we consider that the bottomhole pressure will be higher than the calculated values due to the need to maintain at the mouth of the excess pressure for the selection of produced products in the system surface, and the pressure in the reservoir will be lower due to the initial selection of oil and water production wells, the physical absence of conditions for flow of oil in an artificial reservoir becomes obvious.

The aim of the invention is to increase oil recovery, reducing energy and material costs for mine development and the prevention of environmental hazards.

The aim is achieved in that in the known method of field development, including the construction of wells and systems of surface discharge of water from aquifers in the oil reservoir, an oil flow from the oil deposits into the secondary Deposit and subsequent oil extraction from secondary deposits on the beneficial use of, deposits the share of natural energy characteristics in shielded and have hard water mode and the field exploit three types of wells, of which peritonei equipped with underground separators for separating oil and water and (or) for separation of liquid and gas, and report the oil reservoir to the secondary reservoir, surge equipped with sungami and tell shielded the s reservoir and the secondary reservoir with water horizon having permeability less than that of deposits, and beneath them, producing inform the secondary reservoir with surface selection of the reservoir to the secondary reservoir is carried out the number of high permeability and having the maximum excess over oil deposits and oil extraction from secondary deposits selected gas.

The development of the field of the claimed method is carried out with the use of natural forces, without the supply of external artificial energy, when the regulation of technological processes and this dramatically reduces the cost of operation. Reducing energy and material costs allows to achieve high ratios of oil recovery, to develop deposits and deposits, the exploitation of which known methods unprofitable. How feasible as odnolistovymi and multilayer deposits. Message productive and unproductive strata contributes to the flow and accumulation of oil in the upper layer under the action of gravitational forces as it occurs in natural conditions during the formation of oil and gas deposits are heavy. Message oil deposits, secondary deposits and water horizon egalitarian wells leads to equalization of the above formation pressure in these objects, and this prevents man-made catastr the result from buckling insulating layers.

The essence of the proposed method is illustrated by drawings. Figure 1 shows graphs illustrating energy preconditions of the method, figure 2 - scheme implementation, and figure 3 - layout of underground equipment in perechodnik wells.

Graphs figure 1 reflect the dependence of the pressure P at a depth H wells, the values of h_EOIh_NCand p_EOI, R_NCreflect, respectively, the depth and the initial pressure in the secondary deposits and oil deposits. Shown in the graph, the curve 1 indicates the pressure in the reservoirs along the vertical section to the development of the field, curve 2 represents the pressure in the filled oil well when you message her with the oil reservoir, and curve 3 represents the pressure in the well when reporting it to the oil reservoir and the secondary reservoir.

Figure 2 shows the secondary reservoir 4, shielded oil reservoir 5 and water horizon 6. The Deposit is exploited peritonei wells 7 producing wells 8 with surface 9 and egalitarian wells 10 with the sump 11. Egalitarian well may be provided with a controllable valve located in the depth interval from the reservoir 4 to the reservoir 5 and the water horizon 6 (the drawing is not specified). The oil and water layers are separated by a plane KSS, and the movement of fluids when implementing ways is as indicated by the arrows.

Figure 3 shows Peretola bore 7 with a column of tubing 12, check valves 13 and packers 14.

The method is carried out in stages as follows.

The first step is designing field, select the layers for the secondary deposits and water horizon, technological and economic calculations. On known data about the performance of productive and unproductive strata build curve 1 the pressure distribution in the layers along the vertical section of the Deposit, and the known density of the products of oil deposits build curve 2, reflecting the pressure in conventional wells, reported only from the oil reservoir. If the Deposit has not been exploited before applying the proposed method, the difference of the pressures in the borehole and the surrounding subsoil on the same mark is increased to the wellhead, the value of the differential pressure at a particular depth can be defined as the product of the difference in the densities of water and oil on the distance from the reservoir to the estimated depth and is usually 3-4 MPa for 1 km, i.e. for example, when the depth of the productive stratum 3 km excessive pressure at the wellhead will be about 10 MPa. As the differential pressure increases toward the mouth of the well, to ensure the most favorable EN reticency conditions flow of products from the oil reservoir to the secondary reservoir 4 choose lying at a small depth. For the formation of secondary deposits, you can use one or more high permeability layers, securely isolated from vistalogix horizons to prevent contamination of these aquifers and the atmosphere with hydrocarbons and having any power mode. In order of preference selected for the secondary reservoir, the reservoir can be represented depleted oil reservoir, a gas Deposit, non-productive water-bearing horizon. The possibility of using secondary deposits aquifer considered from the position values of the waters.

In those cases, when the field before applying the proposed method was exploited by other methods and pressure in oil reservoirs has decreased compared to the initial values, i.e. the way in depleted fields to extract residual oil, curves 1 and 2 assess the possibility of accumulation of oil in the secondary deposits: the flow of oil in the reservoir will be possible, if the pressure p_EOIthere will be less pressure in the well defined by the curve 2 at the level of h_EOI. Otherwise, the application of the method is postponed to a later date, when the pressure p_NCwill rise to the required values, or spontaneously, or by accelerating alignment preveden the x pressure in the reservoir balancing wells.

Water horizon 6 is designed to increase the pressure in the layers 4 and 5, a declining due to selection of them oil in cases of inadequate compensation selection influx contour or plantar water and for draining water from the reservoir 4 through egalitarian wells 10, if the pressure in this reservoir will begin to exceed the initial value. Water, the horizon may have a permeability less than that of the reservoir communicated with him deposits, deposits placed below, and equalization bore 10 is supplied with a sump. These signs provide long-pickup reservoirs reservoirs 4 and 5 in egalitarian well, which is explained as follows.

The decrease in the pick-up layers of oil deposits when used in the method of downhole cross flooding is caused by clogging of the filtration channels solids breed, removed from the aquifer. Mudding is, if the particle size is greater than or slightly less than the flow areas of the filter channels. Because of the cross-section of the channels and the corresponding dimensions transported out of the reservoir or filtrating into the layer of particles is proportional to the permeability, this known characteristic collector, you can choose the aquifer, so that leaves the terminal particles freely injected into the oil reservoir. In fact the beam, when the aquifer is located below the oil reserves, the largest particles settle in the sump wells under the action of gravitational forces. The additional effect of placement of the aquifer below the oil deposits caused by high water temperature, higher neftevyshek properties.

At the second stage, the practical implementation of the method. New fields razvarivat peritonei 7, 8 and extractive egalitarian 10 wells (figure 2). Peritonei wells 7 are drilling on a separate oil deposits or groups of deposits, combined as a single object, but does not exclude the simultaneous involvement in the development of each peritonei well all deposits multilayer deposits. Peritonei wells may be equipped with underground separators (figure 3), of which the lower placed at the depth of the oil reservoir 5, is used to separate oil and water and to divert water from upstream production, and the top placed on the depth of the secondary reservoir 4, is used to separate gas from liquid. The method may be carried out without shown in figure 3 separators, structurally made of tubing 12, check valves 13 and packers 14 and when using other known types. In particular, for the separation of water from n the PTI can be used gravity or hydrocyclone separators [John A. Veil. Interest revives in downhole oil-water. Oil and Gas Journal, 2001, Vol.99, pp.47-56], and to separate the gas and liquid can be used known gas anchor.

Egalitarian 10 wells are drilling for alignment given pressure they provide the reservoir to maintain reservoir pressure at the level of the initial values. Analyzing the layers of oil deposits and secondary deposits in the balance wells, or in the interval below KSS, or at the bottom of the reservoir, or through the entire thickness of the layer when placing egalitarian wells for oil-bearing contour.

Production wells 8 are drilling large diameters and sparse grid because of the high permeability of the formation of secondary deposits allows to exploit them with high flow rates at low depressions. Producing wells reported with surface 9.

Fields produced by known methods, mining, peritonea and egalitarian wells may be constructed by retrofitting existing wells. The formation of secondary deposits in these fields will begin after the construction of egalitarian and perechodnik wells and increase the pressure in the oil deposits to such size that the pressure in the filled oil peritonei well exceeded the pressure in the secondary reservoir (figure 1). On new deposits of oil flow in the secondary hall is ü will begin after construction perechodnik wells.

When implementing the method, the oil is transported in Protocol well from the oil reservoir and flows into the secondary reservoir under the action of pressure differences, which are determined by comparing curves 1 and 3 in figure 1. During the flow pressure in the oil reservoir 5 (2) decreases and the secondary reservoir 4 is increased, the most significant changes in pressure occur in the formation zone adjacent to peritonei well. The pressure change will be more significant in low-permeability shielded deposits. As a result of increasing pressure in the secondary reservoir water it displaced outside the zone of high pressure in the reservoir, as well as in the oil reservoir and water horizon through the balance hole 10. Lowering the pressure in the oil reservoir will flow into the water reservoir through the balance hole and of the water-saturated part of the reservoir below KSS.

The flow of oil through the bore 7 from the reservoir 5 into the reservoir 4 is accompanied by a decreasing pressure in the wellbore, the allocation of oil free gas. Specific volumes supererogate gas and mark the beginning of the degassing of oil in the well 7 is determined by the gas content and saturation pressure. The degassing of oil doubly reflected on the intensity of the flow. On the one hand, free gas will reduce the average density of the product in pereto the Noah well, and this will increase the differential pressure between the well and lands with a corresponding increase in the intensity of the flow. Increase the flow of flowing oil will contribute and the resulting gas-lift effect. But, on the other hand, the filterability of the product in the form of a gas-liquid mixture into the formation of secondary deposits will deteriorate, repression on this layer will increase. To reduce the negative effects from the degassing products in peritonei well, it provide a separator that is used to separate gas-liquid mixture into separate phases. In the figure 3 embodiment, the separation takes place in the string of pipe 12 and after output from the column pipe 12 in the annulus through the valve 13, is placed above the upper packer 14. It is possible to use, for the purposes of phase separation centrifugal and other known construction downhole separators. Separated in the separator free gas will occupy the upper part of the well and will be introduced in the upper part of the secondary deposits, and the liquid in the lower part of the perforated interval, the repression in the reservoir will decrease.

The flow of oil from the reservoir 5 into the reservoir 4 will be characterized by the appearance of water in production and the consequent increase of water content. The presence of water in production leads to a decrease in the intensity of the flow as a result of at which helicene density products in peritonei well in the interval marks deposits 4 and 5, and because of the deterioration of the filterability of oil-water mixture in the secondary reservoir. However, it should be noted that the flow of oil because of its watering will not stop, but will decrease. Complete cessation of flow of oil in the secondary reservoir will occur only if the reservoir deposits 5 near the well 7 obwodnica completely, i.e. when will be completely depleted stocks of mobile oil, and the well will be in the path of oil. This is a very important well-known circumstance that determines the effect of achieving a high oil recovery using the proposed method, due to the unbalanced pressure in the oil-saturated part of the reservoir and in water-filled wellbore and in detail discussed in [Journal “Oil industry”, 1998, No. 9, S. 43-45].

To reduce the negative effect of irrigation products and to increase the intensity of flow, the well 7 supply underground separator for separating oil and water, for example, of the type shown in figure 3. The separation of the phases in such a separator occurs under the action of gravitational forces in the column 12 after receipt of the product through the valve 13. After separation of the phases, the oil will accumulate in the upper part of the column 12 and introduced into the reservoir 4, and the water accumulated in the lower part of the column 12 and absorbed by the layer 5 online is rule below KSS or introduced in nistlerooy layer (the drawing is not specified). Necessary to absorb excess water pressure caused by the difference of the densities of the liquids in the column 12 and the annular space. Because the annulus to the level of the lower valve 13 is filled oil-water mixture, and the same interval in the column 12 is filled with water having a higher density, the pressure at the bottom of the pillars of the considered fluids will vary, the pressure in the column 12, for example at the level cap will be higher than the pressure in the annular space on the same level and above the pressure in the reservoir. To use the form in this way excessive pressure to divert water from the column 12, the annular space overlapping the lower packer 14.

The creation of secondary deposits is accompanied by irreversible loss of part of the coming oil due to adsorption her rock formation on the surface of the filtration channels of the oil film, which is not laundered at the subsequent displacement of oil from the reservoir with water or gas. The amount of the loss is determined by the properties of the reservoir rock, the geometrical dimensions of the secondary deposits, the value of specific surface area of the collector. To reduce the loss of oil, the reservoir for the formation of secondary deposits choose from a number of high permeability and high porosity and deposits from turut gas.

High-permeability reservoirs are characterized by low intensity surface, and the difference between these reservoirs of low permeability to measure specific surface area up to 100 times. Adsorption losses of oil is proportional to the specific surface rocks, and the distinctive feature of the method for selecting layers with high permeability for secondary deposits aimed at reducing the loss of oil. In addition, the use of high-permeability reservoirs for secondary deposits will reduce repression on the reservoir when the oil flow, increases the intensity of flows, reduces the duration of the development of the field.

The volume of the film of oil in the reservoir, resulting in a total loss of oil, you can reduce the minimum size of the secondary deposits. Such a result can be achieved in two ways: either by selection of gas from forming in the secondary reservoir gas cap, or a continuous selection of oil and gas from secondary deposits wells 8. Since the timing and rate of oil extraction from secondary deposits in the system surface 9 in most of the conditions of application of the method is given and the settlement rate, the etching gas may be the most simple and effective method of maintaining minimum deposits. In other cases, the operation of the secondary deposits carried out with the neighbors known criteria fields with gas cap.

Advantages of the method is most significantly manifested when using it to develop deposits, the exploitation of which known methods unprofitable, the development of deposits in inaccessible terrain and the sea, to create a strategic oil reserves to prevent environmental threats. The advantages are as follows.

Low material costs of deposits by the present method allow the development of facilities, operation of which is well-known methods unprofitable. This allows you to engage in the development of deposits and deposits with off-balance-sheet reserves of oil and gas, to further deposits, considered to be produced by the known methods, but have achieved low rates of oil recovery, to develop fields with complex geologic conditions, including high water content, at great depth strata, with their low productivity and other use of the method in such conditions and with a limited number perechodnik wells may require a long time for flow of oil from reservoirs in the secondary reservoir and the subsequent selection of the oil on the beneficial use of secondary deposits will be expediently carried the ü after a certain for a long period after the start of the flow. Emerging oil reservoir in such a situation can be considered as the tank farm, to use accumulated oil depending on market conditions, seasonal fluctuations in demand for oil, forming thus the state strategic reserves.

The advantages of using the method at the marine deposits in hard-to-reach terrain, protected areas, etc. due to the simplification of the surface, reducing environmental risk from wells and surface facilities. Peritonei and egalitarian wells do not require maintenance during operation, can be securely sealed on the mouth. As for wells, because given the high permeability of the reservoir to the secondary reservoir, such wells are drilled on a sparse grid, operated with high performance waterless oil and this simplifies the system surface, reduces the cost of oil production. The choice of the high permeability of the reservoir to the secondary reservoir (supercollector) and regulation of the extraction of oil to reduce the deadweight losses allow the use of such layers as a component of the surface, post production wells away from perechodnik and egalitarian, for example, up to the rebellion of the formation of secondary deposits in the direction of the seashore or grancabriocontinue zone.

The ecological advantages of the method is caused, on the one hand, reduce environmental hazards from wells and surface facilities, from the alignment of a given pressure in the interacting layers, from the reduction of corrosion of pipes and equipment and other Main advantage, on the other hand, due to enhanced oil recovery, volume reduction of residual rolling oil after the development of the field, preventing spontaneous uncontrolled flow of this oil in the upper aquifers or reservoirs through the destroyed wells under the action of forces, which is above the energy basis of the proposed method.

1. The way of the oil field development, including the construction of wells and systems of surface discharge of water from the aquifer in the oil reservoir, an oil flow from the oil deposits into the secondary Deposit and subsequent oil extraction from secondary deposits on beneficial use, characterized in that the reserves for the share of natural energy characteristics in shielded and have hard water mode, and the field exploit three types of wells, of which peritonei well tell the oil reservoir and the secondary reservoir for flow and accumulation of oil in the upper layer under the action shall eat of gravitational forces, egalitarian well informed shielded reservoir and the secondary reservoir with water horizon for equalizing reservoir pressure and prevent buckling of breeds and production wells reported secondary reservoir with surface, the choice of the reservoir to the secondary reservoir is carried out among high-permeability layers, with the maximum excess over oil deposits.

2. The method according to claim 1, characterized in that water horizon chosen from the ranks having permeability less than that of layers shielded deposits and secondary deposits.

3. The method according to claim 1, characterized in that water horizon chosen from the ranks beneath oil deposits, and balancing supply wells zumpfe.

4. The method according to claim 1, characterized in that before oil extraction from secondary deposits selected gas.

5. The method according to claim 1, characterized in that peritonei supply wells underground separators for separating oil and water and/or for the separation of liquid and gas.