RU2247237C1 - Method for analysis of multi-bed wells - Google Patents

Abstract

FIELD: oil and gas extractive industry.

SUBSTANCE: method includes lowering equipment into well and performing analysis during extraction of oil from oil beds. In accordance to invention after raising down-pumping equipment from the well liquid is replaced with degassed liquid, and research is performed during pumping in of degassed liquid into oil beds and extraction of degassed oil from oil beds, at the same time pumping is performed using exhaust gases under high pressure from moving compressor, and extraction of degassed oil - by letting exhaust gases out of the well. During that on basis of share of oil beds in total debit of product and extraction and on basis of face pressures during extraction and removal bed pressures of oil beds are determined together with their productiveness coefficient.

EFFECT: higher reliability and precision.

1 ex

Description

The invention relates to the oil industry and can be used to study low-production multilayer wells.

At present, there is no satisfactory method for investigating the operation of individual unproductive oil reservoirs in multilayer wells, since exploration in operating wells is difficult, and the available depth meters do not have satisfactory sensitivity. This can be explained by the fact that previously such unproductive oil reservoirs, due to economic inefficiency, were not introduced into industrial development at all.

At present, new methods have been proposed for the development of unproductive oil reservoirs of multilayer deposits by rationally combining them into production facilities [1], [2]. However, there is no reliable way to control and optimize the mode of operation of unproductive oil reservoirs.

There is a method of researching the individual operation of exploited oil reservoirs, which we adopted as a prototype, which includes the descent of a deep flow meter into a well through a string of tubing and tubing and conducting research when taking oil from oil reservoirs [3]. This method is applicable for the fountain and tubing operation of the well at medium, high and high productivity. However, the known method has several disadvantages.

When transferring a production well from fountain and compressor operation to deep pump operation, this method is not always possible to apply. Firstly, it is not always possible to lower the deep flow meter along the annular space between the production casing and tubing string, there are times when the deep flow meter is lost. Secondly, the used deep flow meters do not have satisfactory sensitivity, and in the case of unproductive multilayer production wells, they do not allow the individual productivity of individual layers and separate layers to be distinguished in the total productivity of the formations.

The objective of the invention is to increase the accuracy and reliability of the study of formations of low-production multilayer wells.

This problem is solved by the fact that in the method for investigating a multilayer well, including the descent into the well of instruments and conducting research when taking oil from oil reservoirs, after lifting the downhole pumping equipment from the well, the well fluid is replaced with degassed oil, and the studies are carried out when the degassed fluid is injected into oil reservoirs and the selection of degassed oil from oil reservoirs, while the injection is carried out by high-pressure exhaust gases from a mobile compressor, and the selection is degassed Anna oil - by issuing the exhaust gas from the well.

The proposed research method is as follows.

The fluid present in the well is replaced with degassed oil from a given field or degassed low-viscosity oil from another field, or a wide fraction of light hydrocarbons (BFLH). A deep flow meter and other deep devices are lowered into the well to study the operation of oil reservoirs and separate layers, and with the help of an exhaust compressor, exhaust gases are pumped into the well, which displace oil from the well into the oil reservoirs. Depth gauges record in time what happens when the exhaust gas is injected, a decrease in the liquid level in the well, at the same time, the pressure of the exhaust gases is determined at the wellhead, and the degassed oil is determined to be injected with a deep flow meter separately for the layers and separate layers. After reaching the maximum reduction in the level of degassed oil in the well, the injection of exhaust gases is stopped, the well at the mouth is opened into a special pipe that exhausts gases to a safe distance, at least 25 meters long, and exhaust gases are released into the atmosphere. Downhole pressure sharply decreases in the well and the flow of degassed oil from oil reservoirs occurs, the rise in oil level is recorded over time. The depth flow meter determines the flow of oil through the layers and separate layers. By oil reservoirs, by the difference in their shares in the total injection and total oil inflow, one can judge the difference in reservoirs in terms of reservoir pressure; based on the average share in the injection and inflow, the oil production rate and the productivity coefficient of each individual reservoir and separate layer are determined for each well.

Here is an example of the implementation of this research method at a production well operating three oil reservoirs: 1st, 2nd and 3rd. The well depth l = 1000 m, the depth of the 1st, 2nd and 3rd oil reservoirs is equal to: 970, 980 and 990 m, respectively. Their initial reservoir pressure was equal to hydrostatic, respectively: 97, 98 and 99 at. The volume of a well with a diameter of D = 0.15 m is

The exhaust gas pressure generated at the wellhead by a mobile compressor can reach P _y = 100 at. When the density of the injected degassed oil γ _n = 0.8 t / m ³ bottomhole pressure can reach

The current reservoir pressure in the 1st, 2nd and 3rd reservoir is respectively R _PL1 = 80, R _PL2 = 90 and R _PL3 = 70 at. The oil productivity coefficient for the 1st, 2nd and 3rd strata is respectively η ₁ = 0.05, η ₂ = 0.03 and η ₃ = 0.07 t / (day.at). With a bottomhole pressure of 180 atm, the 1st reservoir will receive oil

q _z1 = η ₁ (P _sn -P _pl1 ) = 0.05 · (180-80) = 5 t / day or 6.25 m ³ / day,

2nd layer will take

q _z2 = η ₂ (R _{sn -R pl1} ) = 0.05 · (180-90) = 2.7 t / day or 3.375 m ³ / day

and the 3rd layer will take

q _s3 = η ₃ (R _sn -P _pl1 ) = 0.05 · (180-70) = 7.7 t / day or 9.625 m ³ / day,

in all three layers

q _z = q _z1 + q _z2 + q _z 3 = 5 + 2.7 + 7.7 = 15.4 t / day or 19.25 m ³ / day.

It will take more than one day to displace degassed oil from the wellbore into oil reservoirs with high-pressure exhaust gases. The initial share of the 1st, 2nd and 3rd layers in the total injection is 32.5%, 17.5% and 50%, respectively. With the release of gas, the initial bottomhole pressure may be P _c = 20 at. Then the oil inflow from the 1st, 2nd and 3rd layers will be, respectively:

q ₁ = η ₁ (P _PL1 -P _s ) = 0.05 · (80-20) = 3 t / day or 3.75 m ³ / day,

q ₂ = η ₂ (P _pl2 -P _s ) = 0.03 · (90-20) = 2.1 t / day or 2.625 m ³ / day,

q ₃ = η ₃ (P _PL3 -P _s ) = 0.03 · (70-20) = 3.5 t / day or 4.375 m ³ / day,

in general, q = q ₁ + q ₂ + q ₃ = 3 + 2.1 + 3.5 = 8.6 t / day or 10.75 m ³ / day, or in shares of 34.9%, 24.4% and 40.7%.

By the performance of some i-th formation during oil injection

q _zi = η _i · (P _sn -P _pli )

and back at release (selection) of oil

q _i = η _i · (Р _pli -Р _c )

it is possible to determine the reservoir pressure of this reservoir

for example, on the 1st layer

then you can determine the productivity coefficient of the 1st layer

Thus, according to the known total injection and the share of the i-th formation in the total injection, according to the known total production rate and the share of the i-th formation in the total production rate and bottomhole pressures during injection and release (selection), it is possible to determine the individual reservoir pressure of the i-th formation, and then determine the individual productivity coefficient of the i-th formation in a particular well under study.

Based on the obtained individual productivity coefficients for wells, their strata and isolated layers, it is possible to create an effective, constantly operating, deterministic mathematical model for developing an oil field, with which it is possible to control and optimize the process of selecting oil reserves.

Sources of information:

1. Lysenko V.D., Graifer V.I. A method of developing multilayer deposits. - Patent of the Russian Federation No. 2142046. Priority from 04/22/98.

2. Lysenko VD, Graifer VI. The method of developing a multilayer oil field. Patent of the Russian Federation No. 2188938. Priority from 02.28.01.

3. Reference guide for the design of development and operation of oil fields: Design development / Ed. Sh.K. Gimatudinova. - M .: Nedra, 1983.

Claims (1)

A method of investigating a multilayer well, including the descent into the well of instruments and conducting research during the selection of oil from oil reservoirs, characterized in that when researching in a low-producing well after lifting the deep-pumping equipment from it, the well fluid is replaced with a degassed fluid, and the research is carried out when the degassed pump is injected fluid into oil reservoirs by high pressure exhaust gases from a mobile compressor and the selection of degassed fluid from oil reservoirs by exhaust s gas from a well, wherein the proportion of oil reservoirs in the total production rate of injection and sampling and downhole pressures during injection and extraction of oil reservoirs define reservoir pressure and productivity index.