A method for localizing sources of anthropogenic pollution of aquifers

 

The invention relates to the field of study wells and can be used to quickly identify hidden sources of groundwater contamination in the oil industry. The method includes the integrated use of shooting natural electrical potentials in the near-wellbore zone and vibroacoustic CEMENTERIO wells. By shooting natural electrical potentials determine the presence and direction of cross-flows of the fluid in the borehole. Through the vibroacoustic CEMENTERIO wells define the elements of well design and localize the depth intervals casing cement, which is the source of pollution and are subject to corrective cementing. The invention is aimed at timely identification of the need for repair work aimed at elimination and prevention of technogenic contamination of groundwater by specifying the interval of these works in depth. 9 Il.

The invention relates to the field of environmental monitoring, in particular to the protection of the hydrogeological environment in oil-producing regions by promptly identifying hidden sources of salinization of groundwater pityevoye Tataria) observed facts of salinization of drinking water, one of the reasons for which are downhole fluid flows caused by defects in the annulus cement (mainly the conductor or partially performing its functions technical columns). The elimination of such pollution sources is carried out by correctional defective cementing intervals, which requires their precise localization in depth.

There is a method of identifying cross-flows of liquid and evaluate the quality of a porous cement, including thermometry, the method of radioactive isotopes and various modifications of the acoustic logging (Krivko N. N. Equipment GIW. - M.: Nedra, l991, 384 c.).

The main disadvantage of this method is the high complexity and lack of efficiency, due to the need o wells from service and extensive preparatory work, involving teams of well workover and special equipment installation mast wireline truck dismantling and removing the downhole equipment and so on).

Closest to the proposed invention the technical essence is a way of vibroacoustic CEMENTERIO (VAC). The definition of quality is and formed the analyzed element in the wellbore to zvukoprovodnost (production column, the conductor, etc.,) through the boundary between media with different acoustic impedance, defined by the coupling in the system metal - cement (Blizeep A. B., Kozlov A. C., Markovich E. C. and other Acoustic method for the diagnosis of the quality of the cement bond behind the conductor well. RF patent №2055176, IPC E 21 In 47/00 for 1996, bull.№6). To do this, at the end of the analyzed column shape extending along it a short acoustic pulse, and then register the secondary (reflected) signals. The increase in amplitude of the secondary signal indicates the presence of defects in the annulus cement, and the time of the receipt allows us to localize the last length and depth (to determine the distance of the borders of the defects from the mouth of the well known propagation velocity of acoustic oscillations in the metal columns).

The disadvantage of VAC is that it is not possible to judge the presence or absence of cross-flows, because even with a very low overall quality of cementing, for example the conductor, there may be areas concatenated cement or snug fit of clay rocks, preventing annular circulation of liquid and salinization of freshwater aquifers. Thus, the lack otsutstvie cross-flows of liquid.

The objective of the invention is to increase the reliability of the results of studies on the localization of the sources of anthropogenic pollution of aquifers.

The problem is solved by a method including the vibroacoustic CEMENTERIO wells (VAC) using the shooting natural electrical potentials (EP) in the near-wellbore area.

What's new is that in addition to VÁC are shooting natural electrical potentials (EP) in the near-wellbore zone. By shooting EP on the size and sign of the gradient of potential in the near-wellbore zone to determine the presence and direction of cross-flows of the fluid in the borehole. Then in the presence of flows using the VAC determine the quality of the cementing elements of well design and location of defects in the annulus cement on them responsible for the occurrence of overflows. Based on these data and determine the need for repair and insulation works for each of the elements and localize the depth intervals of their length, subject correctional cementing.

The use of shooting EP to detect the presence of cross-flows or leakage of saline water based on the occurrence Elektronen on the surface, moreover, the magnitude and sign of the potential gradient in the near-wellbore zone indicate the intensity and direction of the fluid, respectively. (Shvydkin E. K., Napalkov C. N., Chernyshev, M., and others Identify sources of drinking water contamination of oil field wastewater method of electric potentials filter.// Geology, exploration and development of oil and bitumen deposits. Kazan: publishing house of Kazan University press, 1997, S. 171-176).

However, this method without involving the VAC does not identify a specific element in the wellbore and to localize the depth interval of length determining existence of cross-flows and underlying correctional cementing. In addition, the EP independently (without VAC) does not resolve the question about the necessary repairs, because flows can occur at considerable depth beyond the depth of the freshwater aquifers and water for technical purposes, without causing man-made pollution. Thus, the disadvantage of shooting EP is the lack of reliability of the obtained results do not allow to judge the necessity and specific venue correctional cementing.

This obrazki reliably determine the need for repair and insulation works and specific interval in the depth of the structural element of the well (mostly conductor) subject to corrective cementing. Separate application of any of the above methods does not provide the necessary reliability of the results.

Presents figures explain the essence of the invention, where Fig.1, 4, 7 presents the plans isopotential; Fig.2, 5, 8 - graphs of electric field distribution of Fig.3, 6, 9 - semantography on cited as an example the wells.

The method is performed in the following sequence.

The method of EP are shooting natural potentials in the area of the subject well. The magnitude of the potential gradientThe EP within background values (up to 2 mV/m) corresponds to the natural filtration processes, a further increase of this parameter indicates the presence of cross-flows of fluid, and a negative anomaly corresponds to the direction of the last top-down and positive upwards. The definition of intervals cross-flows are the results of VÁC, representing a graph in the coordinate depth - amplitude of the secondary signal, the latter is calibrated in values: the hastily passed field testing of the 200 wells OJSC Udmurtneft and allowed to localize more than 20 sources of pollution of fresh water.

As an example, a particular implementation of the proposed method the results of the survey of SLE.547 (Fig.1-3), 726 (Fig.4-6) and 354 (Fig.7-9) OJSC Udmurtneft.

On SLE.547 there is a negative anomaly EP, proving the existence flows from top to bottom (Fig.1, 2). Cause overflows are defects in the annulus cement conductor in the interval 5-145 m (Fig.3).

On SLE.726 anomalies EP are absent (Fig.4, 5), which corresponds to the absence of flows and good quality cementing of the conductor (Fig.6).

On SLE.354 positive anomaly EP (Fig.7,8), indicating the presence of flows from the bottom up, associated with defects in the annulus of cement in the interval 10-187 m (Fig.9).

Technical and economic efficiency from the application of the proposed method is achieved by increasing the reliability of the results of studies on the localization of the sources of anthropogenic pollution of aquifers. A comprehensive application of the methods of the EP and the VAC provides a fundamentally new technical result (unattainable with separate application of any of the above methods), allowing high accuracy to determine the need for repair and insulation works, certain spacing element Konstrukcija works to eliminate sources of pollution and as a consequence on the ecological situation in the oil producing regions.

Claims

A method for localizing sources of anthropogenic pollution of aquifers, including the vibroacoustic CEMENTERIO wells (VAC), characterized in that in addition to VÁC are shooting natural electrical potentials (EP) in the near-wellbore zone by shooting EP detect the presence and direction of cross-flows of the fluid in the borehole, and using the VAC define the elements of well design and localize the depth intervals casing cement, which is the source of pollution and are subject to corrective cementing.

 

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FIELD: oil and gas extractive industry.

SUBSTANCE: device has body with ports in lower and upper ends, main sensitive elements in form of turbines and packing elements, placed in pairs at body ends, side port made in body between main sensitive elements and converter, connected to surface equipment. In side pipe, mounted inside the body between main sensitive elements, additional sensitive element is placed in form of turbine and thermal sensor. Lower end of side pipe is connected to side port. Diameter of turbine of additional sensitive element is less than diameter of turbines of main sensitive elements. Converter is a control block mounted above body including sleeves locator and electronic microprocessor device.

EFFECT: higher precision.

1 dwg

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