Abstract
A large number of oil and gas wells at the late stage of operation are characterized by high and constantly increasing water cut of the extracted product. One of the reasons for the high water cut is the presence of production casing leaks. The occurrence of production casing leaks is connected both with the quality of primary cementing and various operating conditions of wells. To solve this problem, different technologies are applied with the use of plug-back mixtures and technical means, each of which has its own advantages and disadvantages as well as its own application area. In particular, the packers of various structures are widely used. Among the many options, the retrievable packers benefit in the market even in the case of their relatively high costs due to their easy removal and reuse. The article presents the results of the work on the development of a new structure of the retrievable packer with cable termination glands and hydraulic opening system in the well. The structure of the retrievable packer was tested in the laboratory conditions with the use of a purpose-designed test rig and in the field environment. The designed stand for testing individual structural units and the packer as a whole is a casing string simulator in which the test packer is placed. The stand is equipped with a hydraulic cylinder to simulate the movement of the packer, hydrostations to simulate hydraulic loads on the packer and breakthrough fluid from the leakage of the production string, circulation pumps to simulate circulation pumping through the packer. Field tests were carried out at one of the fields in Eastern Siberia, Russian Federation, at wells with very high water cuts. Full compliance with the claimed requirements concerning the reliability of operation of mechanisms and well plugging of the leak interval was shown. Besides that, the advantage of the packer is the possibility of communication between spaces above and below the packer. At the same time, the possibility of technological washing, acid treatment, killing and other technological operations is preserved. The use of packer during repair and insulation works in wells has made it possible to reduce the duration of works on the average by 2.5 times.
Highlights
The issue of developing new technical means, which can be effectively used to solve problems related to leaks in production casing, comes at an opportune time, in particular, to take account of the well stock growth at a late stage of development
Used technology of fixing leaks with the help of lowering into the well an additional production casing and subsequent cementing is not free from shortcomings, the main of which are the high cost of repair and insulation works (RIW) and restriction of the full bore of well
The article presents the results of works on the development of a new structure of a retrievable packer with cable termination glands and hydraulic opening system in the well
Summary
The issue of developing new technical means, which can be effectively used to solve problems related to leaks in production casing, comes at an opportune time, in particular, to take account of the well stock growth at a late stage of development. Fixed packers are simpler in design and can usually be used at higher temperatures and pressures than retrievable packers They have a more compact structure and can, be used in widely deviated wells. The disadvantages of packers include integrity damages of the rubber or polymer part of the packer due to the impact of high formation temperatures and pressure, as demonstrated in [13], [14], acid compositions for bottom-hole formation zone treatment and formation hydraulic fracturing, as is proven in [15], [16]; the possibility of cross cracks in wells, especially in inclined and horizontal ones as shown in [17], [18]; complexity of packer seating operations in horizontal wells and widely inclined wells, as demonstrated in [19]. The article presents the results of works on the development of a new structure of a retrievable packer with cable termination glands and hydraulic opening system in the well
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