# The method of developing multilayer oil field

(57) Abstract:

The invention relates to the oil industry, namely, development of oil and gas fields, containing several levels of different types of collectors. Provides lower operating costs, increase current selections. the increase of the recovery factor and the increase in reserves during the joint operation of several horizons. The essence of the invention: before using the field determine the optimal bottomhole pressure selection of products from each of the productive horizon. Choose the basic horizon that contains the largest reserves of oil, then put into operation producing wells at optimum downhole pressure to the base of the horizon, for the remaining horizons hole pressure wells cause downhole pressures on the underlying horizon and calculate the adjusted hydraulic connection between the well bore. 4 tab., 5 Il. The invention relates to the field of oil industry, namely, development of oil and gas fields, containing several levels of different types of collectors.s for its collection characteristics, independent wells for each horizon [1].

This method requires large capital investments and operating costs. As the development of the grid has to be sealed, which entails the construction of additional pipelines and structures and increases the value of the extracted oil.Closest to the proposed method is a method for the joint operation of horizons [2], the essence of which is as follows: the injection of fluid in each horizon is through self-injection wells, and the joint oil extraction from aquifers through production wells.The main disadvantage of the above method is that in the process of joint operation horizons are not taken into account their collection of features, which reduces the current and target process performance.So in 6 wells in the test area of the Arkhangelsk field of Tartary [2] conducted a joint operation Vereisky and Bashkirian deposits. The results of these studies (table 1) shows that when the joint exploitation of deposits total average daily flow Nesna 60%.In a separate operation Vereisky and Bashkirian deposits the oil recovery factor is 16.7% and 9.7%, respectively. When the joint exploitation of the oil recovery factor is 8.4%, which reduces reserves by 30%.The aim of the proposed method of development of an oil field is the reduction of operating costs, increase the current selection, increase the recovery factor, and hence the increase in reserves during the joint operation of several horizons.This goal is achieved by the proposed method, including the exploitation of the oil field, which is separate injection of the displacing agent in productive horizons through a grid of injection wells and joint selection of products from horizons through production wells.What's new is that before using the determined optimal bottomhole pressure selection of products from each of the productive horizon. Selects the base horizon, containing the largest oil reserves. Then put into operation producing wells at optimum downhole pressure to the base of the horizon, and the rest of the horizons of the umbrella. As with the joint operation of horizons optimal bottomhole pressure can be provided for only one horizon.The method is used as in the previously operated, and newly introduced fields (areas of the field) and is carried out in the following sequence.Fields under development and operating each horizon separately independent grid production and injection wells, producing wells additionally reveal previously not exploited horizons, thereby condensing the grid (as a result of increased oil recovery), and injection wells leave unchanged. Therefore, separate injection of the displacing agent is carried out through self-injection wells, and the joint selection of the product is conducted through production wells (Fig. 1, POS.1).On the newly developing fields of Buryats multilateral injection wells (Fig. 1, POS. 2), revealing yourself every horizon, or independent system of injection wells for each horizon (Fig. 1, POS.1), the net producing wells are drilling a single at all horizons for their joint use.A study of injection wells are conducted on 4-5 steady-state operation modes differing from each other by the pressure and volume of injection. For each mode:- measure the flow rate and bottom hole pressure to build the indicator diagram;

- remove the injectivity profile (for evaluation of the coverage of horizon flooding and its interval pickup);

- remove recovery curves (fall) pressure curves and establish the mode of injection to determine the reservoir properties of the horizon;

- interpret the results obtained by known techniques, and then build the appropriate indicator charts and graphs.For efficient production of reserves modes of injection wells should provide maximum coverage of the flooding, subject to conditions prevent leading breakthrough of injected water in producing wells.Such conditions occur when the injection of the displacing agent under the optimal values of the discharge pressure, which is determined by the complex of the researches.For example, the region of optimal pressure injection on the indicator diagram corresponds to the area of curvature indicator diagram. To do this, perform complex hydrodynamic studies and calculations. In the specific example was used, the dependence of permeability on pressure, described in accordance with the following formula [3]

< / BR>

where k

_{0}the initial permeability of the formation;

k - current permeability of the formation;

- - coefficient of variation of initial permeability with changing pressure,

P is the initial reservoir pressure,

P

_{PL}- the current reservoir pressure.The physical meaning of the coefficient is as follows. The coefficient reflects the change in reservoir properties reservoir when the pressure change per unit. At lower bottomhole pressure, increasing depression, the first flow rate increases linearly. Further, due to reduction of permeability by the exponential law, the flow rate decreases sharply.Thus, using the ratio to determine some optimal bottomhole pressure at which the maximum possible flow rate.The coefficient is determined for each horizon according to a study wells hydrodynamic methods. Then calculate the dependence of changes in the flow rate from giving the bit of oil. Thus, the gain for each of the productive horizon of their optimal bottomhole pressure selection of products.When the joint development horizons the optimal bottomhole pressure can be provided for only one horizon. For other horizons optimal bottomhole pressure will be dependent on the pressure for the base of the horizon and calculate the adjusted hydraulic connection between aquifers in the wellbore.For example, in the simplest case, without regard to hydraulic losses in the segment of the borehole between the horizons, the optimal bottomhole pressure is calculated by the formula

< / BR>

where P is the bottomhole pressure for the studied horizon, IPA

P

_{b}- optimal bottom hole pressure, the base of the horizon, IPA

- oil density, kg/m

^{3}< / BR>

g - free fall acceleration, m/s

^{2}< / BR>

h is the distance from the base to the settlement horizon, mThus, the joint operation of horizons, when downhole pressure selection of products expect to optimize the basic horizon, allows to minimize losses in oil production, reduce operating costs by a significant reduction in unproductive is.An example of a specific implementation.An example implementation of the method was provided for the experimental site Cheremhovskogo field. Before calculating downhole pressure injection wells were studied geological and geophysical characteristics of the reservoir and properties of reservoir fluids.Industrial oil content associated with carbonate reservoirs verey horizon, Bashkir and tournaisian tier and Sandstone reservoirs of the Tula and bobrikovsky horizons.The reservoir characteristics of the productive deposits are presented in table 2.According to the results of hydrodynamic studies were calculated bottomhole pressure injection wells and the coefficient (table. 3).Receiving for each of the productive horizon, was calculated dependence of change of flow rate of oil from the downhole pressure selection of products from each horizon (Fig. 3).As is known, the optimal pressure corresponds to the highest flow rate of oil. It is evident from Fig. 3 shows that for the productive deposits of the Bashkir maximum flow rate is achieved at a 2.9 MPa, for bobrikovsky deposits at 3.8 MPa, for tournaisian deposits - at 4 MPa.Wcities bobrikovsky horizon and Bashkir, respectively.The studies were found optimal bottomhole pressure at all productive sediments (table 4).Further, we investigated how the horizon to operate under optimum conditions in the case of joint operation of horizons, as in the case of joint development of optimal bottomhole pressure can be provided for only one horizon. For other horizons they will be dependent on the pressure for the base object and were calculated with correction for hydraulic communication between the well bore by the formula [2].As the base object were selected sediments of the Bashkir, as these sediments are concentrated largest oil reserves, compared to the rest (table 2). Therefore, when the joint development horizons loss in production will be minimal when optimizing downhole pressures on Bashkir tier.Calculations were performed. Analysis of the results showed the following (Fig. 4).For clothes-Bashkirian options separate and joint operational optimization by Bashkir tier give the same result, the maximum flow rate reaches a 12.03 tons/day.Cyrus layer close to the performance of separate development. The maximum oil production rate when optimizing the Bashkir are 4,29 t/day, with separate development of 4.4 tons/day.For tournaisian deposits of the joint operation horizons when optimizing the Bashkir gives the worst results. The maximum oil production rate when optimizing the Bashkir be 4.1 tons/day, in a separate operation 4.7 tonnes/day.In the case of joint development horizons when optimizing the Bashkir cumulative oil production almost reaches the accumulated oil in a separate operation. In Fig. 5 shows that the cumulative production of oil in the joint development horizons when optimizing by Bashkir tier is 4391 thousand tons for 43 years and for the separate operation - 4489 thousand tons for 37 years. Loss in case of joint development of the productive deposits when optimizing by Bashkir tier will be 98 thousand tons of oil.When the joint development horizons without optimization of downhole pressure Bashkir layer, and, for example, on the tournaisian stage cumulative production would be 3055 thousand tons for 32 years and losses amounted to 1434 thousand tons of oil.Thus, the proposed method of joint development of productive mountains is ice will amount to 2.2% compared with separate operation, and without the proposed method, they would have amounted to 32%. The wells in both cases is almost 3 times compared to the separate operation of productive horizons.Sources of information

1. Muslimov R. H., Abdulmazitov R., improving the technology of ineffective development of oil fields in Tatarstan. Kazan Tatar book publishing house, 1989, S. 41.2. Muslimov R. H., Abdulmazitov R., improving the technology of ineffective development of oil fields in Tatarstan. Kazan Tatar book publishing house, 1989, S. 62.3. Berniev K. S., Kochina, I. N., Maksimov Century Meters Underground hydromechanics. M.: Nedra, 1993, S. 53. The method of developing multilayer oil fields, which produce separate injection of the displacing agent in productive horizons through a grid of injection wells and joint selection of products from horizons through production wells, characterized in that before the start of operation, determine the optimal bottomhole pressure selection of products from each of the productive horizon, choose the basic horizon with the largest reserves of oil, then put into operation producing wells at optimal z is s, dependent optimal bottomhole pressure of the underlying horizon and calculate the adjusted hydraulic connection between aquifers in the wellbore.

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FIELD: oil and gas extractive industry.

SUBSTANCE: device has operation columns of upper and lower well zones, placed eccentrically one inside the other in upper zone of well, double airlift column, mounted in upper well zone, and double airlift column, connected to operation well of lower well zone, separation column, mounted coaxially to operation column of upper well zone, and cementation pipe. According to invention, in a well with significant power of non-productive zone it is equipped with additional separating column with cleaning channels for lowering drilling tool therein and drilling well to lower well zone with removal of drilling slurry by double airlift column of upper zone through cleaning channels. Additional separating column is combined coaxially with operation column of lower well zone and is rigidly fixed to separation column.

EFFECT: higher efficiency.

1 dwg, 3 cl