SU1359435A1 - Method of investigating injection wells - Google Patents

Abstract

The invention relates to the exploration of oil and gas wells in the field of geophysical exploration (C). The purpose of the invention is to improve the accuracy and reliability of detecting the places of fluid inflow (outflow) and to determine the intervals of fluid movement in the annular space C. interpretation of the data obtained from this measurement, and determine the intervals for further research. Then C is transferred to the injection mode during the time t V / Q, where V is the internal volume of the pipes from the funnel to the mouth, m, Q is the pickup, C. Next, C is transferred to the sampling mode and measurements of T are taken in the selected interval 0.5-5 h after the start of water withdrawal from C. T. selection, where R is the distance from the tubing to the casing, m; a - temperature – flow conductivity of the medium filling the annular space,. The change of operating mode C and measurements are periodically repeated. The obtained thermograms are compared with the background and are interpreted. 2 Il. S (L 00 ate WITH Ntiii 00 cl

Description

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The invention relates to injection well studies in monitoring the development of oil fields and, in particular, can be used in field geophysical surveys of oil and gas wells.

The aim of the invention is to improve the accuracy and reliability of detection of places of inflow (outflow) of fluid. and determining the fluid flow intervals in the annulus of the well.

The method of investigating injection wells is based on the time dependence of the radius of the thermal research zone. At short times, the well has a determining effect on the recorded temperature field, and at longer times the contribution of the surrounding rocks increases. This makes it possible to separate temperature signals from the well and the surrounding rocks by choosing a special research technique (temporal filtering of temperature signals).

The method is carried out as follows.

The temperature distribution along the wellbore is measured using a thermometer descending into the well, pre-interpretation of the data obtained during this measurement is carried out, and intervals for further studies are determined. Then, the well is transferred to the injection mode and is made during the V / Q time t, then the well is switched to the extraction mode and the temperature distribution is measured in the defined interval 0.5–5 h after the beginning of the water withdrawal from the well. not after a periodic change of injection for sampling, followed by interval recording of temperature in each of the identified zones of temperature anomalies for a time not exceeding 2 after the start of sampling. The change in the mode of operation of the well and the measurement of the periodicity is repeated, and the interval measurements are made with an overlap of 30-50 m. The obtained thermograms are compared with the background and are interpreted as

Upper and Delay Limits Corresponding

R

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There are two extreme cases of the position of the instrument and tubing (tubing) relative to the casing axis and their dimensions. The lower boundary | corresponds to the eccentric position of the device, tubing and casing (the device lies on the tubing, and tubing on the casing). The upper limit corresponds to the centered position of the instrument, tubing and casing.

When measuring, it is assumed that the recording device lies on the wall of the tubing, and the tubing on the wall of the casing string due to the non-vertical position of the borehole axis. This arrangement of the tubing in the wellbore, and, accordingly, of the recording device in the tubing is implemented in practice at some distance from the wellhead and from the packer installed on the tubing funnel.

The choice of the upper limit of the delay interval corresponds to the value of the time when the minimum allowable value of the temperature signal of rocks can be recorded with a thermometer in the case of a casing of large diameter when the device is located along the axis of the well.

FIG. 1, 2 presents graphs of implementations of the method.

FIG. 1 is indicated: 1 - thermogram recorded along the entire wellbore 20 minutes after the start of sampling, 2-5 - thermograms recorded respectively in the intervals: 1120-820 m, 850-520 m, 550-220 m, 250-0 m immediately after multiple transfer of the well from the injection mode to the selection mode. The STL-28 serial thermometer was lowered into the well through a lubricator and tubing. 5 The funnel tubing was at a depth of 1309 m. The perforated interval was 1331, 6-1336, 8 m. The injection capacity of the Q hole 300 m3 / day.

FIG. 2 is designated: 1 - thermogram recorded along the entire wellbore 22 minutes after the start of sampling, 2 thermogram recorded immediately after transferring the short-circuit of the injection mode to the sampling mode. Studies conducted through the tubing. The tubing funnel was located at a depth of 1303 m. The interval of 1347.2-1350 m was perforated. The injection capacity of the well Q is 800 m / day.

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Example 1. After the pressure was etched, the thermometer was lowered into the well to a depth of 1120 m. Water injection into the well was carried out for 12 minutes. After this time, the well was transferred to the selection mode. 20 minutes after the start of sampling, the temperature distribution was recorded (Fig. 1, thermogram 1) in the tubing in the depth range of 1120–0 m. After thermogram 1 was recorded, the thermometer was lowered to a depth of 1120 m. Water was pumped into the well for 12 min. transferred it to the sampling mode and simultaneously with the last recorded temperature distribution (Fig. 1, thermogram 2) in the tubing in the depth range of 1120-820 m, the well was re-drilled for 12 min and transferred to the selection mode. Immediately after the transfer of the well to the selection mode, the registration of temperature (Fig. 1, thermogram 3) in the tubing was started in the depth interval of 850-520 m. .

From the research results it can be seen that the temperature anomalies in the depth intervals: 70–120 m, 210–280 m, 860–900 m (Fig. 1, thermogram 1) are not related to casing leakage, but are due to near-wellbore processes, as in thermograms 2-5, there are no similar anomalies. The measurement carried out by the flow meter in a free column along the entire wellbore confirms the conclusion issued from the results of thermal studies on the tightness of the casing metal column.

Thus, from the research results it can be seen that the casing string is tight at the indicated depth intervals. I

Example 2. After the pressure was relieved, a thermometer was lowered into the well to a depth of 1280 m. Water injection into the well was carried out for 15 minutes. After this time, the well was transferred to the selection mode. 22 minutes after the start of sampling, the temperature distribution was recorded (Fig. 2, thermogram 1) in the tubing in the depth range of 1280 - O m in the mode of water extraction from the well. After re0

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Thermogram 1 hys- tration lowered the thermometer to a depth of 310 m. We carried out water injection into the well over.

 12 minutes, transferred it from the injection mode to the sampling withdrawal, and simultaneously with the latter, they recorded the temperature distribution (Fig. 2, thermogram 2) in the tubing in the depth interval of 310 0 O m in the selection mode.

From the research results it follows that the temperature anomalies at a depth of 200 m (Fig. 2, thermograms 1, 2) are due to leaks

5 of the casing string, since the nature of the temperature distribution in the depth interval of 310-0 m in thermograms 1 and 2 is one.

  Factors confirming the conclusion made from the results of thermal studies in the well are: the occurrence of water on the surface between the production column and the conductor column (water that has appeared on the surface of the well at the wellhead, according to the results of the analysis is injected, and non-reservoir), the tubing is sealed at a depth range of 340–0 m (as measured by the RGD-4 depth gauge), the annular flow in the well below the depth of 200 m is not observed, as the temperature gradient (see FIG. 2, thermogram 1) practically does not change in the depth interval of 1280–200 m.

Thus, from the research results it can be seen that the production string is not hermetic at a depth of 200 m.

To implement the method it is necessary to use downhole thermometers with a resolution of 0.01 K and

inertia no more than 1 s.

t

5 The proposed method makes it possible to increase the unambiguity of the detection of the places of fluid inflow (outflow) in the intervals covered by the tubing. This results in a reduction in labor costs, since it eliminates the need for tripping operations and, as a result, creates an economic effect of about 800 rubles per well. The implementation of the method allows one to determine wells in which salinity of freshwater sources occurs due to annular circulation, which is very important for environmental protection.

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Claims (1)

Invention Formula The method of investigating a blower is 4} iix wells, which includes recording the temperature change along the wellbore upon multiple transitions from the moment of injection of the liquid to sampling and comparing thermograms, which is aimed at increasing the accuracy and reliability of detecting the inflow sites ( outflow of the fluid and determining the intervals of fluid flow in the annulus of the well; measure the temperature 0.5–5 h after the start of sampling from the well; determine the inflow points by temperature. anomalies m, produced in every one of you  a fft / e // i / ff; / ffC / rf / In the temperature range of the temperature anomalies, the registration of the temperature change for a time not exceeding 2 after the start of the sampling, and the duration of the injection of the liquid is determined by the formula t -X ten where V is the internal volume of tubing from in Ronki to ust. m Q - injectivity of the well,, R - distance from the tubing to the casing columns, m; a is the thermal diffusivity of the medium filling the annular space,. Ge / 7m0gr / 1 / mb / 13 / 4i / 7ff / 7W - j-i / phage /  i .§ C} (eat (at a / acrr7fj repf ospaMMij / / "f5 16 77 r 100 700 300-400 500600-700 6QQ 900 1000ma WITH a Compiled by V.Sidorov Editor M. Bandura Tehred A. Kravchuk Proofreader I. Erdeyi Order 6125/32 Circulation 533 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d, 4/5 Production and printing company, Uzhgorod, st. Project, 4 Fie.2