RU2225506C2 - Method for measuring impermeability of force-pumping well operation string - Google Patents

Abstract

FIELD: oil extracting industry. SUBSTANCE: method includes lowering of packer suspended on hoisting cable into the well, said packer being driven by electrical engine. Method also includes overlapping of well shaft by said packer, creating pressure above the packer by means of pumping fluid into the well, registration of pressure change simultaneously above and below the packer by means of manometers. On basis of manometers display changes permeability of well operation string or packer is detected. Method also includes raising packer to the surface. According to the method, packer is lowered to predetermined depth through tubular space of tubing pipes, in case of operation string impermeability only packer is raised to the surface, and in case of operation column permeability tubing pipes are also raised. EFFECT: increased trustworthiness of information about string permeability, lowered time and resources costs. 2 cl, 1 dwg

Description

The invention relates to the oil industry, and in particular to methods of monitoring the technical condition of the production casing of an injection well in order to determine its tightness to prevent contamination of drinking water, as well as to obtain reliable information about the degree of coverage by the working power of the formation.

Known methods for monitoring studies of the technical condition of the production casing of the injection well, namely for tightness, by flow measurement or thermometry [1 and 2].

However, the known methods are not technologically advanced; their implementation is associated with shutting down the well and is time consuming.

At the same time, the necessity of killing a well requires the call of a team for overhaul of the well and tripping, which leads to a rise in the cost of research. Due to the high cost of research work, this kind of work is often carried out in insufficient volume, which is fraught with negative consequences, namely salinization of the upper drinking water due to leakage of the production string, and erroneous conclusions about the degree of coverage by the working capacity of the formation.

There is also a known method for testing the tightness of the production casing of an injection well [3], which includes lowering a packer into a well on a cable rope brought into working position by an electric motor, closing the wellbore with a packer, creating pressure above the packer by injecting fluid into the well, recording changes pressure simultaneously above and below the packer using pressure gauges, according to whether or not the changes in the indicators of which judge the leak of the packer or operating bosoms, and raising the packer to the surface.

The disadvantage is that the method requires lifting tubing to the surface for its implementation, which is associated with the time consumption of up to 48 hours, using a working team, as well as equipment.

The objective of the present invention is to obtain more reliable information about the leakage of the production string and reduce the cost of time and money.

The problem is solved by the described method, including the descent into the well of the packer on the cable rope, brought into working position by an electric motor, the borehole closing the packer, creating pressure above the packer by injecting fluid into the well, recording pressure changes simultaneously above and below the packer using manometers, according to whether or not the changes in the indicators of which judge the leak of the packer or production casing, and lifting the packer to the surface.

What is new is that the packer is lowered to a predetermined depth through the tubing space of the tubing and when the production string is tight, only the packer is raised to the surface, and if the production string is leaking, the tubing is also raised to the surface. In this case, a pressure gauge for recording pressure changes above the packer is installed at the wellhead.

Preliminary patent research on the novelty of the claimed object was carried out according to the patent fund of the TatNIPIneft Institute with a retrospectiveness of 20 years. The research results showed that similar methods used in the study of wells for tightness, characterized by such a combination of essential features, as the proposed facility, are absent. Therefore, we can assume that the claimed technical solution has novelty and inventive step.

The presented drawing schematically shows the process of testing the injection well for leaks by the proposed method, where the packer and the manometer deflated with it are visible, after the wellbore is closed by the packer sealing element.

The method is as follows.

To implement the method, packers available in the arsenal of equipment with an electric drive and lowered onto a cable-rope through the tubing tubing space, for example, a packer according to the RF patent [4], can be used.

The packer described below satisfies the specified requirements.

It contains a housing, a screw, a running nut. Inside the housing there is a prefabricated rod with a compensation cavity with a piston, a return spring and a travel key.

In the lower part of the housing is located the sealing element of the packer with a protective casing installed with the ability to move around the housing. At the same time, the lower part of the collection rod enters the packer sealing element and has a longitudinal channel with three holes along its entire length through which oil flows from the compensation cavity into the packer sealing element. The compensation cavity is in communication with the pipe space of the well and with the cavity of the sealing element for the piston to operate in hydraulic equilibrium. The packer also contains a reversible electric motor with a gearbox kinematically connected by a lead screw nut.

The method is as follows.

Before the descent of the above-described packer 1, a pressure gauge 2 is attached to its lower part and is lowered to a predetermined depth through the tubing space 4 of the tubing 5 to the cable rope 3, but above the reservoir 6, as shown in the drawing.

Next, through a cable rope 3, an electric current is supplied to the reverser motor of the packer 1, which transmits rotation through the gearbox (the electric motor and gearbox are not shown in the drawing) to the screw that moves the travel nut, the sealing element 7 is released from the casing and then through the actuators overlapping of the wellbore, the cavity of the production casing 8 with a sealing element 7 (see drawing).

Then, from the wellhead by injection of liquid, according to the technical conditions, a pressure above the packer of about 80-100 atm is created, which is held for 15-20 minutes, and pressure is recorded by the wellhead pressure gauge, and also under the packer using the manometer 2 deflated with it. After the estimated time of fluid injection by reverse of the packer motor, its sealing element is brought to its original position and then the packer 1 together with the pressure gauge 2 is raised to the surface. Then the recorded readings of the pressure gauges are compared. At the same time, if the change in the indicators of both pressure gauges coincides, the leakage of the sealing element of the packer is judged. Then the packer is raised to the surface and sent to the production service base to eliminate the cause of its leakage.

When the indicator of the pressure gauge installed on the surface changes, with a constant pressure gauge reading under the packer, a conclusion is made about the leakage of production casing 8. Then the tubing string is raised to the surface, the same packer is lowered onto the cable-rope into the well and the place of leakage is specified by interval testing.

Technical appraisal and economic advantage of the invention are as follows. When using the method, the research results are more accurate, reliable, because, having no information about the tightness of the packer in downhole conditions, the obtained research results may not be reliable. In addition, the study of the method achieves a reduction in time within 15-18 hours, which ensures the efficiency of research work.

Sources of information

1. The book “Satellite of an oil field geologist”. Handbook edited by I.P. Cholovsky, Moscow: Nedra, 1989

2. RF patent No. 2121572, BI No. 31, 1998.

3. RF patent No. 2165001, E 21 17/00, BI No. 10 (prototype).

4. RF patent No. 2162136, 7 E 21 B 33/12, BI No. 2, 2001

Claims (2)

1. A method for testing the tightness of the production casing of an injection well, including lowering the packer into the well on a cable-rope driven by an electric motor, closing the wellbore with a packer, creating pressure above the packer by injecting fluid into the well, recording pressure changes simultaneously above and under the packer using pressure gauges, according to whether or not the changes in the indicators of which judge the leakage of the packer or production casing and lift packer to the surface, characterized in that the packer is lowered to a predetermined depth through the tube side of the tubing and the production tubing packer tightness only lifted to the surface and production casing leaks when raised to the surface as the tubing. 2. The method according to claim 1, characterized in that the pressure gauge for recording pressure changes above the packer is installed at the wellhead.

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