RU2231632C1 - Method of development of an oil pool - Google Patents

Abstract

FIELD: petroleum industry.

SUBSTANCE: the invention is dealt with petroleum industry and may be used at development of oil-pool. The method ensures a possibility of definition of the water water-encroached seams and increase of production rate of a deposit at the expense of realization of water-insulating operations. Substance of the invention: the method provides injection of the working agent through the injection wells and takeoff of petroleum through production boreholes. Gamma-ray logging curves are taken out while holes are in service. For investigated boreholes the subsequent and previous curves of a gamma-ray logging are superposed. Plot a curve of differences between values of the subsequent and previous curves. A maximum difference between their values accept as 100 %. Then they determine dynamics and percent of change of gamma - units in the zones of productive seams. Accept, that traffic of edge waters is weak at change of gamma - units up to 25 %, from 25 up to 75 % - it is average, more than 75 % - it is intensive. On availability of the dynamics of the water encroachment of the seam they judge on the speed of waters edge advancing to the borehole. In the encroached brats the measures on insulation of edge waters are carried out and leveling of a structure of intake capacity of wells. The gamma-ray logging curves are plotted before and after the water-insulating operations. The uneven change of change of gamma characteristics of logging allow to judge about the water-insulation agent penetration process.

EFFECT: the method allows to reveal water-encroached seams and to increase f production rate of the oil pool.

1 ex

Description

The invention relates to the oil industry and may find application in the development of oil deposits.

A known method of developing a water-cut oil reservoir, including periodic injection of hydrocarbon liquid and gelling material through injection wells, injection of a displacing agent and oil extraction through production wells (RF patent No. 2143059, class E 21 B 43/22, publ. 1999.12.20).

The method allows isolation of water-conducting zones of the formation and alignment of the injectivity profile of injection wells. However, the method does not provide for the determination of waterlogged interlayers and quality control of water insulation works, therefore, the increase in oil recovery is not high.

Closest to the invention in technical essence is a method of developing an oil reservoir confined to carbonate reservoirs, including drilling production and injection wells of the main and reserve funds and their perforation in the interval of productive formations, pumping water through injection wells, oil production through production wells, various methods of field-geophysical studies during the operation of wells, in injection wells of the main stock by flow metering asta that does not accept water when it is injected into the reservoir, but discharges water after the injection is stopped when pressure is removed at the mouth of the injection wells, according to the confinement of this layer to the benchmark, intervals are identified that are identical in production and other injection wells, and according to the neutron-gamma method logging determination of filtration characteristics and spread over the area of the interlayer, which does not receive water during injection, but discharges water after the injection is stopped, and drilling production and injection wells of the reserve onda taking into account the distribution of this interlayer over the area (RF patent No. 1322743, class E 21 B 43/20, publ. 04/04/27 - prototype).

The known method does not allow to determine the waterlogged layers, to carry out waterproofing work and, thereby, increase the oil recovery of the reservoir.

The proposed method solves the problem of determining watered interlayers and increasing oil recovery by performing waterproofing works.

The problem is solved in that in the method of developing an oil reservoir, including pumping a working agent through injection wells, taking oil through production wells, conducting gamma-ray logging in wells and identifying interlayers with characteristic properties, according to the invention, gamma-ray logging curves are taken during the operation of the wells, the studied wells combine the subsequent and previous gamma-ray curves, build a difference curve between the values of the gamma units of the subsequent and previous curves, the maximum difference between values of gamma units are taken as 100%, determine the dynamics and% changes in gamma units in the zones of productive layers, it is assumed that the movement of formation water is weak when the gamma units change to 25%, from 25 to 75% - average, more than 75% - intensive, by the presence of watering dynamics, they judge the progress of formation water to the well, in flooded interlayers, measures are taken to isolate formation water and equalize the injectivity profile in wells, gamma-ray logging curves are taken before and after waterproofing operations and by a step change in gamma-ray indices are judged on the passage of the waterproofing agent.

The features of the invention are:

1) injection of a working agent through injection wells;

2) oil extraction through production wells;

3) gamma-ray logging in wells;

4) identification of interlayers with characteristic properties;

5) the removal of gamma-ray logs during the operation of wells;

6) for the studied wells, the combination of the subsequent and previous gamma-ray logging curves;

7) building a curve of the difference between the values of the gamma units of the subsequent and previous curve;

8) accepting the maximum difference between the values of gamma units as 100%;

9) determination of the dynamics and% change in gamma units in the zones of productive layers;

10) the assumption that the movement of formation water is weak when the gamma units change to 25%, from 25 to 75% - average, more than 75% - intense;

11) on the presence of watering dynamics, a judgment on the promotion of formation water to the well;

12) in flooded interlayers, carrying out measures to isolate formation water and align the injectivity profile in wells;

13) removal of gamma-ray logging curves before and after waterproofing works;

14) judging by the abrupt change in gamma-ray indices, the passage of a waterproofing agent,

Signs 1-4 are common with the prototype, signs 5-14 are the salient features of the invention.

SUMMARY OF THE INVENTION

When developing an oil deposit, uneven flooding occurs. It is very difficult to establish which layer and to what extent has been flooded. In the proposed method, the problem of determining the water cut of the layers by means of gamma-ray logging in wells is solved. Subsequent waterproofing works contribute to the increase in the production of interlayers, increase oil recovery deposits.

The method is as follows.

When developing an oil deposit, the working agent is pumped through injection wells and oil is taken through production wells. Gamma-ray curves are taken during the operation of wells. The method is based on the fact that produced water leaches radioactive elements of the rock (salt) and carries them to the producing wells. Radioactive elements of the rock accumulate in the near-wellbore zone, are deposited on the pipes, clay sorb them. In gamma-ray logging, such deposits are determined and recorded. For the studied wells, the subsequent and previous gamma-ray logging curves are combined, i.e. superimpose one curve on another. Normalize curves, i.e. establish a single scale and a single measurement system (gamma, x-rays, pulses / min). A difference curve is constructed between the gamma units of the subsequent and previous curves. Zones are determined where the change in the difference in gamma-ray logging values is noticeable, the duration of the zones is determined in depth and in amplitude (the magnitude of the difference in values). The presence of identified zones determines the movement (inflow) of formation water (it can even be produced as associated water and pumped back into the wells). The maximum difference between the values of gamma units is taken as 100%. The dynamics and% change in gamma units in the zones of productive layers are determined. In producing wells, it is assumed that formation water movement is weak when the gamma units change to 25%, from 25 to 75% - average, more than 75% - intense. By the presence of watering dynamics, they are judging the progress of formation water towards the well. In irrigated interlayers, measures are taken to isolate formation water and align the injectivity profile in wells. Waterproofing works are carried out on fresh, i.e. on unplastic water. Therefore, when injecting water-insulating compositions, the radioactive elements of the rock are pushed away from the well and the value of gamma units decreases. Remove gamma-ray curves before and after waterproofing. By the abrupt change (decrease) in the values of gamma-ray logging, the passage of the waterproofing agent is judged.

Similarly, by injection wells, it is determined where the working agent goes - to the productive layer or past.

Concrete example

An oil reservoir of the Romashkinskoye field is being developed with the following characteristics: porosity - 11.9%, permeability - 0.029 μm ² , oil saturation - 61.1%, absolute mark of water-oil contact - 870 m, average oil-saturated thickness - 8 m, initial reservoir pressure - 11 MPa , reservoir temperature - 25 ° С, reservoir oil parameters: density - 930 kg / m ³ , viscosity - 46 MPa · s, saturation pressure - 1.8 MPa, gas content - 15.2 m ³ / t, sulfur content - 3, 64%

A working agent is pumped - highly mineralized water with a density of 1180-1200 kg / m ³ from the lower horizon through rows of injection wells with 10 wells in each row. Oil is taken through the rows of production wells of 10 production wells in each row. The distance between the wells in the rows is 500 m.

Use archived gamma-ray data obtained in an open wellbore prior to operation, i.e. when drilling.

One of the wells was drilled as producing. The initial flow rate was 7.6 tons / day, the water cut was 60%. After 14 years, water cut increased to 99.4%. Gamma-ray logs are taken in the well. Combine the curve obtained in an open-hole well during its construction and the curve obtained after 14 years of operation, i.e. superimpose one curve on another. Normalize curves, i.e. establish a single scale and a single measurement system - gamma. A difference curve is constructed between the gamma units of the second and first curves. To do this, compose a straight line for the reference points Y = f (x) for a pair of gamma-ray logging curves, where Y are the gamma-ray logging values, x is the well depth. The coefficients (a, b) of the formula for transforming the gamma-ray curves to one averaged curve Y ^* = ax + b are determined, i.e. establish a single scale and a single measurement system - gamma. A discrepancy is found between the calculated parameters Y ^* and the measured Y readings of the re-measurement of gamma-ray log Δ = YY ^* and a curve is constructed of this difference.

For this well, the range of divergence of gamma units is 0.25-10 gamma. The difference between the maximum and minimum values of gamma units when combining gamma-ray logging curves for a given well is taken as 100% (in particular, about 10 gamma). It is revealed that for productive layers the average value of the change (the difference between the values of gamma units) in the development area is 60%. Similarly conduct research in other wells.

It is revealed that in two production wells on three interlayers 1 m thick each, the change in gamma units amounts to about 80-90%. Decide on the implementation of waterproofing works in these layers. 2 m ^{3 of a} liquid-glass insulating solution in fresh water is pumped selectively and interval into these layers. Carry out technological exposure for curing. Remove gamma-ray curves before and after waterproofing. It is determined that in two interlayers there was a decrease in gamma units to almost zero. A conclusion is drawn on the passage of a water-insulating agent into these interlayers. In the third interlayer, a decrease in gamma units occurred by 10%. Make a conclusion about the need for repeated waterproofing measures in this layer.

It is revealed that in three production wells in one interlayer 1 m thick, the change in gamma units is about 20%. They conclude that it is necessary to redistribute the flows of the working agent into the deposits in this interlayer.

As a result of the application of the proposed method, oil recovery increased by 3% and amounted to 41%.

The application of the method will allow to determine the waterlogged interlayers and increase the oil recovery of the deposit due to the carrying out of waterproofing works.

Claims (1)

A method of developing an oil deposit, including pumping a working agent through injection wells, taking oil through production wells, conducting gamma-ray logging in wells and identifying interlayers with characteristic properties, characterized in that the gamma-ray logging curves are taken during the operation of the wells, and the wells under study are combined subsequent and previous gamma-ray curves, build a difference curve between the values of the gamma units of the subsequent and previous curve, the maximum difference between the values of gamma-units they are taken as 100%, they determine the dynamics and% of the change in gamma units in the zones of productive layers, it is assumed that the movement of formation water is weak when the gamma units change to 25%, from 25 to 75% - average, more than 75% - intense, by presence irrigation dynamics judge the progress of formation water toward the well, in flooded interlayers, conduct measures to isolate formation water and equalize the injectivity profile in wells, take gamma-ray logs before and after waterproofing operations and by a step-wise change in gamma-ray logs with DYT on passage of water shutoff agent in flooded interlayers.