RU2533470C2 - Procedure for recovery of tightness in flow strings - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention is related to methods for recovery of tightness in flow strings. The procedure for recovery of tightness in flow strings includes surveys of the flow string leakage position and length, assembly of a sealing packer, running the packer to the well and activation of the packer. The packer mandrel is formed by screening sealing elements (elastomers) and the upper and lower leakproof elements (elastomers). The leakproof elements are divided from each other by limiting inserts. The packer is equipped with anchor bends. The packer mandrel length exceeds length of the flow string leakage. The packer is run-in to the well in run-in position when its outer diameter is more than the string drift diameter. When the packer reaches the planned interval it is activated with expansion of screening sealing elements under load up to inner diameter of the flow string and till the string and packer space is tightened against leak by the upper and lower leakproof elements below and above the seal failure interval. Limitation of the screening elements expansion is regulated due to inner limiting inserts.

EFFECT: method allows exclusion of addition of cuttings or hardened cement paste and reduction of accident rate during operation of wells.

2 cl, 1 dwg

Description

The invention relates to methods for eliminating leaks in production casing, in particular gas, gas condensate, oil, water, and injection wells.

The well-known technology for eliminating leakage of production casing, used in the overhaul of wells of ZAO NRC "Neftemash-Nauka" - a company specializing in the development of new technologies and equipment for the oil and gas industries (http://www.neftemash-nauka.com/tech -rir.htm). This technology consists in creating an impermeable screen by injecting gelling components (HMN) into the well, which prevents the well from being absorbed, and first reinforcing it with cement solution through the tubing string with the addition of surfactants, thereby increasing permeability in pores or fractures of the formation and adhesion to the rock, then a clean solution of cement.

The disadvantage of this technology is: low efficiency and fragility of the duration of the effect of eliminating leaks in production casing (1.5-2 years), then the need for repeated work. Another disadvantage of this method is the high cost due to the large number of additional work (re-injection, drilling cement bridges, dribbling production cores).

Known methods of restoring tightness, slightly reducing the inner diameter of the string, in particular, a method of installing steel adhesives, comprising assembling a mandrel with a longitudinally corrugated pipe at the wellhead, lowering the mandrel with a patch of the patch on tubing or drill pipes and installing it in the interval of casing string disturbance; connection of the discharge line with a deflated pipe string, press-fitting the patch; smoothing the patch with a turning head at an excess pressure of 12 MPa at least 4-5 times; compressing the column without removing the mandrel from the well; lifting a string of pipes with sod, development and commissioning of the well according to the approved plan (http: oilloot.ru./79-vnutriskazliinnye-i-remontnye-raboty/206-ustranenie-negermetichnocsti-obsadnoj-kolorinny).

The disadvantage of this method is: reducing the diameter of the cross section of the production casing, for the restoration of which it is necessary to carry out a number of emergency recovery work with a high degree of complexity and high cost. There may be risks of various complications during the performance of these works.

Known methods for eliminating leakage of production casing using the installation of the installation of electric centrifugal pumps (ESP) with a packer or by cutting off the leakage interval with a two-packer assembly (Afanasyev A.V. Innovator 2011, No. 40).

The elimination of leaks by using the ESP unit with packers is less costly, but these technologies do not exclude the loss of mobility of downhole equipment due to precipitation of rock-containing sludge or cement stone from the leakage interval during well operation, which qualifies as an accident and entails a large number of additional (unproductive) costs to eliminate. There are risks of losing a well.

Closest to the claimed method of eliminating leaks in production casing is a method of isolating an untight portion of a wellbore using the Sharifov packer system described in the patent for the invention (RU No. 2387802, ЕВВ 33/12; E21B 43/00, 04/27/2010). The method consists in lowering the packer system into the well and includes lowering into the well (flowing, gas lift, pumping, injection or piezometric) on the pipe string, either with an open shoe or with a muffled lower end of two packers connected to each other through pipes, each of which is equipped mainly with the barrel, sealing cuffs and above them with a hydraulic anchor rigidly connected to the barrel, and below them an anchoring unit in the form of a cone and die holder with dies, and a stopper fixing the original and / or working its position of the packers, with the placement of a pipe string disconnector-connector above the upper packer, consisting of a fixed and removable element, and the descent of one of the packers above and the other below the leaky section of the production string or perforation interval of the non-operating - unproductive - formation. In this case, after the packers are seated and checked for leaks, they are disconnected above the top packer, hydraulically or mechanically through a disconnector-connector, the pipe string from the packer system, and then either it is lifted above the packer system and left in the well or removed from the well and, instead, lowered above the packer systems underground installation for the operation, injection or exploration of a well with one or more exploited formations.

This method also does not exclude the loss of mobility of downhole equipment due to spillage of rock-containing sludge or cement stone from the leakage interval during well operation, which qualifies as an accident and entails a large number of additional (unproductive) liquidation costs. There are risks of losing a well.

The objective of the present invention is to reliably seal the column-packer space in any interval of the well, eliminating emergencies associated with the precipitation of rock-containing sludge or cement stone and not changing the flow area of the production string in the leakage interval.

The problem is solved in that in a method of eliminating leakage in production casing, including examining the location and length of the leakage interval of the production casing, assembling a packer equipped with anchor units in the form of a cone and ram holder with dies, lowering the packer into the well in a predetermined interval and putting it into working position with sealing the column-packer space below and above the leakage interval, according to the claimed invention carry out the assembly of plugging self-flowing packer, the trunk of which is formed by shielding sealing elements (elastomers) and upper and lower sealing elements (elastomers), and the total length of the packer barrel exceeds the length of the leakage interval, the plugging packer is lowered into the well in the transport position, in which its outer diameter is smaller than the bore diameter production casing, when the planned interval is reached, the packer is transferred to the working position with the expansion under load of the shielding gaskets lementov barrel packer to the calculated diameter equal to the inner diameter of the production casing, and upper and lower sealing elements to achieve sealing mullion-packer space above and below the leakage slot, the limit value of the expansion of the screening element is controlled by internal restrictive inserts (cup); the initial and working positions of the packer barrel are fixed using anchoring units in the form of a cone and a die holder with dies.

The lowering of the plugged packer can be carried out in conjunction with downhole pumping equipment, with the installation of the packer in the layout of the launched equipment by an intermediate link.

The inventive method of eliminating leaks in production casing is illustrated by the technological scheme shown in the drawing. Positions marked: production casing 1 with leakage interval 2, perforation interval 3, tubing: docking unit 4 and lower geophysical funnel 5, upper anchor unit 6, lower anchor unit 7, upper sealing elements (elastomers) 8, lower sealing elements (elastomers) 9, shielding sealing elements of the leakage interval (elastomers) 10, load distribution elements between elastomers 11.

The technical result when using the proposed method is expressed in achieving reliable tightness of the production casing without reducing the diameter of its bore.

A method of eliminating leaks in production casing is as follows. According to the results of research (pressure testing, geophysical studies of wells) determine the location and nature of the leakage (length) of the production string, select the length and diameter of the plugging packer. Depending on the installation method, the plugging packer is lowered on the technological tool, if the installation is planned separately from the tubing, or install it as an intermediate link into the production equipment lowered into the well, if the installation is planned in conjunction with the deflated tubing. The packer is lowered in the transport position, in which its outer diameter is 10-15 mm less than the bore diameter of the production casing of the system. When the planned interval is reached, the geophysical lot is referenced to the geological section to ensure that the plugging packer is accurately set to the desired interval, the system is unpacked, the plugging packer is put into working position, while the sealing screening elements - the upper and lower sealing elements - expand under load (pressure) to the required values. When removing the system from the well, after failure, the shape of the elastomers returns to its original (transport) position and the layout (system) rises to the surface.

The advantage of this method of eliminating leakage in production casing is to reduce accident rate during well operation, the ability to remove the system from the well at each repair, to carry out planned activities without the difficulties associated with reducing the diameter of the inner section of the production casing in the well. In addition, this method allows, if necessary, and certain structural additions (the introduction of a conduit packer into the design along the barrel of the plugging packer under the sealing and sealing elements), to ensure communication between the overpacker and subpacker annulus to provide the required control of the well operating parameters, as well as enabling technological flushing of pumping equipment and well killing using standard methods. This technology allows you to install the plugging packer in any interval of the well, separately from the tubing, and to include it as an intermediate link in the layout when lowering the ESP, SHGN, fountain lift, PPD packer.

Claims (2)

1. A method of eliminating leakage in production cores, including examining the location and length of the leakage interval of the production casing, assembling a packer equipped with anchor units in the form of a cone and a die holder with dies, lowering the packer into the well in a predetermined interval and putting it into working position with sealing the column-packer space lower and higher leakage interval, characterized in that they perform the assembly of plugging equal bore packer, the trunk of which is formed by with anizing sealing elements (elastomers) and upper and lower sealing elements (elastomers) with a total barrel length exceeding the length of the leakage interval, the plugging packer is lowered into the well in the transport position, in which its outer diameter is less than the passage diameter of the production string when the planned interval is reached the packer is put into working position with the expansion under load of the shielding sealing elements of the packer barrel to a design diameter equal to the inner diameter of the production casing, and the upper and lower sealing elements until the column-packer space is sealed above and below the leakage interval, while the restrictions on the magnitude of the expansion of the shielding elements are controlled by internal restriction inserts (glasses): the initial and working positions of the packer barrel are fixed with using anchor nodes in the form of a cone and die holder with dies. 2. The method according to claim 1, characterized in that the lowering of the plug-in packer is carried out in combination with downhole pumping equipment, with the installation of the packer in the layout of the descent equipment by an intermediate link.

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