RU2186935C2 - Process of isolation of inflow of stratal water - Google Patents

Abstract

FIELD: development of oil and gas fields. SUBSTANCE: process includes of sinking of tubing string with packer into well. Packer is set above water exhibiting portion of pool. Then blocking and grouting compositions are fed into well in sequence. Compositions are pumped through tubing string when hole clearance is open. In this case packer is transportation position. Compositions are fed till their separation boundary appears to be opposite packer. Well fluid is driven through hole clearance to well-head. Remaining portion of blocking composition is fed through hole clearance. Grouting solution is used as last portion of blocking solution. Chemically destroyed component is present in composition of this solution. Then packer is set in working position. Grouting composition and blocking compositions are pumped simultaneously. Grouting composition is pumped through tubing string into water exhibiting portion of pool. Blocking composition is injected through hole clearance into productive portion of pool. Radii of zones formed by pumped compositions are kept same. EFFECT: good plugging up of water exhibiting portion of pool with simultaneous fixing of its productive portion. 3 dwg

Description

 The invention relates to the field of oil and gas fields and can be used to isolate waterlogged formations in production wells, including with weakly cemented reservoirs.

 There is a method of limiting the influx of formation water into production wells by injecting various plugging components into waterlogged formations / 1 /.

 The disadvantage of this method is the reduction in the permeability of the non-flooded productive part of the formation due to the penetration of plugging material during waterproofing operations.

 Closest to the described method is a method of isolating the influx of formation water, which consists in installing a packer over a water-producing interlayer, pumping air through a column of tubing (tubing) until a steady state filtration and plugging composition in the air stream in the mode of aerosol formation in a water-developing interlayer and at the same time the injection through the annulus of oil or stable condensate into the gas-saturated part of the formation, followed by exposure of the well for the time of setting of tamponir agent / 2 /.

 The disadvantage of this method is the possible complications in the development of the productive part of the reservoir after conducting insulating works of water-producing interlayers, especially the reservoir, which is composed of weakly cemented rocks, since in the subsequent after insulating works the development of the productive reservoir (especially gas), it is necessary to create significant depressions on the reservoir to remove the pumped into it hydrocarbon fluid. In addition, when conducting waterproofing operations when delivering technological solutions to the bottom, it becomes necessary to inject well fluid into the formation, which leads to its loss and decrease in permeability of the productive part of the formation.

 The objective of the invention is the provision of high-quality plugging of the water-developing part of the formation while securing its productive part.

 This object is achieved by the fact that when implementing the method of isolating the influx of formation water, including the descent into the well of a string of tubing with a packer, installing a packer above the water-developing part of the reservoir, feeding it into the well and subsequent simultaneous injection through the string of tubing into the water-developing part of the reservoir plugging composition and through the annulus into the productive part of the reservoir - blocking composition when the packer is in the working position, according to the invention, a part of the blocking and the plugging compositions are fed into the well sequentially through the tubing string with the annulus open and the packer in transport position so that their interface is opposite the packer, while the wellbore fluid is forced out through the annulus at the wellhead, and the remainder of the blocking composition, where as the last portion, use a plugging solution with a chemically destructible component in its composition, feed through the annulus, pump them into the formation, support Single radius zones created pumped compositions identical.

 The drawing shows a diagram of the implementation of a method of isolating the influx of formation water: a - feeding blocking and plugging compositions into the well, b - position of blocking and plugging compositions in the well before pumping them into the formation, c - position of blocking and plugging compositions in the reservoir as a result of the method; 1 - well casing, 2 - tubing string, 3 - packer in transport position, 4 - packer in working position, 5 - filter (perforation), 6 - water-developing part of the formation, 7 - productive part of the formation, 8 - blocking composition, 9 - plugging composition, 10 - fluid for pumping the blocking composition into the reservoir, 11 - fluid for pumping the plugging composition into the reservoir, VNK (GVK) - water-oil (gas-water) contact.

 The invention consists in the following.

 To isolate the water-developing part of the formation 6, a tubing string 2 with a packer 3 is lowered into the well in the transport position and set it above the water-developing part of the formation. Then, through the tubing string 2, part of the blocking composition 8 is sequentially pumped into the well in an amount equal to the volume of the annulus (the annular space between the casing 1 and the tubing string 2) above the packer 3, and the plugging composition 9 with the annulus open. In the process of supplying these solutions to the well (see drawing “a”), the borehole (filling) fluid through the annulus is displaced from the borehole and taken to the wellhead.

 The plugging and blocking compositions are fed to the bottom of the well so that their interface is against the packer 3, i.e. so that the blocking composition 8 is in the annulus above the packer, and the plugging composition 9 is in the tubing string 2 and in the annulus below the packer. Next, the packer is brought into working position, i.e. using it isolate the tube space from the annulus (see drawing "b").

 If there is a danger of mixing the blocking and plugging compositions during their joint movement in the well, then a small portion of the separation liquid is pumped between them.

 Then the remaining parts of the plugging and blocking compositions are fed into the pipe and annular spaces and pumped into the formation (see drawing “c”). The fluid supply rates are selected so that the radii of the zones created in the bottomhole zone by the injected formulations are maintained the same, which eliminates the plugging of the productive part of the formation and the blocking composition getting into the isolated water-developing part of the formation.

 If the porosity of the formation in the water-developing and productive parts is the same, then the rate of supply of fluids pumped into the pipe and annular spaces to crush the blocking and plugging compositions into the formation will be proportional to the thicknesses of the corresponding parts of the formation.

 As the last portion of the blocking composition, a plugging solution with a chemically destructible component in its composition is used. The volume of this portion is taken in such a way as to fill the existing cavities in the bottom-hole zone of the productive part of the formation.

 After the described operations are completed, the packer is unpacked (brought into transport position) and removed to the surface, while in the well bore, the squeezing fluids are previously changed back to the filling fluid (if they are not). Next, a tubing string is lowered into the well. After the setting time of the plugging composition and the solution has expired, a chemical reagent is fed into the well in the interval of the location of the plugging solution in the formation (in the interval of the productive part of the formation), under the influence of which the chemically destructible component of the plugging solution is destroyed. As a result of the destruction of this component, the hardened plugging solution turns into a porous material (filter), which prevents the further destruction of the productive formation and the removal of rock particles by the flow of the formation fluid during development and operation of the well.

 Then the well is cleaned of the chemical reaction products, mastered and put into operation.

 An example implementation of the method.

 It is necessary to isolate the inflow of produced water in the well with a depth of H = 1200 m, a casing string of 168 mm (outer diameter Dн = 168.3 mm, inner diameter Dв = 148.3 mm), we use tubing 73 mm (outer diameter dн = 73 mm, inner diameter dв = 62 mm). The thickness of the flooded part of the productive gas reservoir ho = 2 m, the thickness of its productive part hr = 5 m, the porosity of the reservoir m = 0.15. The radius of cavern formation is Rk = 0.5 m, caverns at this distance occupy half the volume of rocks of the reservoir.

The plugging of the flooded part of the reservoir is carried out to a depth of Rtc = 2.5 m, then the volume of the plugging composition is:
Vtc = π (RTC -Dn ^{2 2/4)} ho m = 5,9 m ^3.

Accordingly, the volumes of the blocking composition Vbc and the plugging solution with the chemically destructible component Vtr will be:
Vbc = π (Rtc ² -Rk ² ) hr m = 12.7 m ³ ,
Vtr = π (Rk -Dn ^{2 2/4)} hr / 2 = 2 m ^3.

We find the volumes of the pipe Vt and annular V ₃ spaces:
Vt = π dv ² N / 4 = 3.6 m ³ ,
Vз = π (Dв ² -dн ² ) Н / 4 = 5 m ³ .

 We use condensate as a blocking composition, which is pumped into the productive part of the formation, as a plugging solution with a chemically destructible component - an aqueous solution of a mixture of Portland cement and aluminum grains with a content of the last order of 10%, and as a plugging solution - a solution of hypane, which in contact with formation mineralized water acquires viscoplastic plugging properties.

Thus, after the tubing string with the packer is lowered into the well and installed above the water-developing part of the formation, the tubing string with the annulus open at the wellhead is sequentially pumped:
5 m ³ (annulus volume) of the blocking composition is condensate,
3.6 m ³ (tubing volume) of the plugging composition - hypane,
we bring the packer into working position, then simultaneously feed the remaining part of the plugging composition (5.3-3.6 = 1.7 m ³ ) into the tubing and into the annulus - the remaining part of the blocking composition (12.7-5 = 7.7 m ³ ) with the plugging solution as the last portion - 2 m ^{3 of a} solution from a mixture of Portland cement with aluminum grits; these solutions are pushed into the formation by selling fluids: through the tubing - 3.6 m ^{3 of} fluid used to pump the plugging composition into the water-developing part of the formation, through the annulus - 5 m ^{3 of} fluid used to pump the blocking composition into the productive part of the formation.

 Since the thickness of the productive part of the reservoir is 2.5 times greater than the thickness of the flooded part of the reservoir (hg / ho = 2.5), respectively, to comply with the condition of equal radius of zones created by the injected compositions, the rate of forcing of the blocking composition is 2.5 times the rate of forcing plugging composition, which is achieved by pushing into the reservoir the estimated volumes of plugging and blocking compositions in one time.

Next, we unpack the packer, remove it to the surface with the used fluids replaced with the filling fluid in the well and lower the tubing string into the well. After holding the well for the setting time of the plugging composition and the solution, we feed a portion of the alkaline solution into the interval of the reservoir to dissolve the aluminum grains in the composition of the plugging solution. The volume of this portion will be at least the volume of the annulus in the interval of the reservoir:
Vsh = π (Dv ² -dn ² ) hr / 4 = 0.02 m ³ .

 After dissolving the aluminum grains, the well is washed from the reaction products, mastered and put into operation.

 When implementing the described method, intended mainly for weakly cemented loose reservoirs, during operation of which cavern formation and removal of rock particles into the well is observed, not only the water-developing part of the formation is isolated from the well, but also its productive part is fixed. When implementing the method, the borehole (filling) fluid is not lost and is not crushed into the reservoir.

Literature
1. Bulgakov R. T. et al. Restriction of formation water inflow into oil wells. M .: Nedra, 1976, p. 98-104.

 2. RF patent 1804549, cl. E 21 B 33/138, 1993.

Claims (1)

 A method of isolating the influx of formation water, including the descent of the tubing string with a packer into the well, installing the packer above the water-developing part of the reservoir, feeding the well into the well and subsequent simultaneous injection of the plugging composition through the tubing string into the water-developing part and through the annulus into the productive part of the reservoir blocking composition when the packer is in the working position, characterized in that part of the blocking and plugging compositions are fed into the well sequentially through the tubing string with the annulus open and the packer in transport position, so that their interface is opposite the packer, while the well fluid is forced out through the annulus at the wellhead, and the remainder of the blocking compound, where the plug portion is used as the last portion with a chemically destructible component in its composition, it is fed through the annulus, they are pumped into the reservoir, maintaining the radii of the zones created by the injected compositions, one ovymi.

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