Method for plugging of lost-circulation zones. RU patent 2506409.

FIELD: oil and gas industry.

SUBSTANCE: suggestion refers to remedial cementing of wells at oil deposits, in particular, to plugging of lost-circulation zones, methods of well casing recovery. Method of los-circulation zone plugging includes running-in of cementing string to plugging space. Two components of cementing mixture are pumped in sequence through cementing string until the first component egresses fully in annular space through an open end of cementing string and they are squeezed further by displacement liquid. At that before running-in of cementing string to plugging space packer and cutting sleeve consisting of body with end-to-end channel of circular section with side port and spreader, housing, driving washer are installed additionally. Cementing string is run-in upstream the plugging space per 30 m. Two components of cementing mixture are pumped in sequence until the first component egresses fully in annular space through an open end of cementing string. Packer seating is performed. Squeezing of the second component is continued through cementing string and pressure is increased simultaneously up to 2 MPa, at that driving washer can move and the first component egresses through spreader under pressure to flow of the second component. Components of cementing mixture are squeezed. At that squeezing of the first and second components is made by batches 3-4 times at volume ratio of the components in batches from 1:4 up to 1:1 respectively starting from 1:4 and completing with 1:1. When the last batch of cementing mixture components egresses from the cementing string squeezing is completes, and squeezing of cementing mixture components is made by displacement liquid considering that a cement plug equal to 20 m is to be left in the well. At that stock oil is used as displacement fluid.

EFFECT: improving efficiency of remedial cementing works due to increase of sweep depth, formation of homogenous and dense cementing mixture and due to equal distribution and mixing of pumped components.

1 dwg, 2 tbl, 1 ex

Offer applies to repair and thermal insulation works at wells in the oil fields, in particular to the isolation of absorbing layers, and also to methods of recovery lining wells.

Known method of repair and isolation works in the well, based on application of composition with a mass fraction of components: resin 50-90%, 5%aqueous solution of sodium hydroxide 5-40%, produced water Devonian horizon - the rest (patent RU №2250983, IPC 21 33/138, publ. 27.04.2005, bul. №12).

The main disadvantage of this method is the low efficiency of the method in the conditions of intensive acquisitions, in particular, with the purpose of exception of an emergency during preparation and uploading of the composition of the curing time of the composition of the picked from 2 hours or more. In the result of which in conditions of intensive acquisitions insulating screen does not manage to be formed, and this leads to a takeover of the composition.

The closest to the technical nature of the proposed solution is a way to isolate the absorbing layers by descent casting pipes, sequential injection water filling pipes components mixture and their subsequent joint into the reservoir, and to improve the quality of the insulation the first component during exit through the open end of the filling pipes raise in the annulus, but as the exit from the casting of pipes of the following component together with him in absorbing formation of the annular space forced the first component in the ratio of 3:1, and before download first component in the annulus is pumped lightweight liquid (A.S. no 823559, IPC 21 33/138, publ. 23.04.1981).

The disadvantage of this method is its low efficiency due to the slight penetration into the reservoir mixture due to the high content in its composition of the solid phase, high viscosity and quick hardening. At the same time formed a stone from mix based on cement, though characterised by a high mechanical strength and hardness, fragility of it is so high that it is quickly destroyed when exposed to shock loads. In addition, the mixing of the components in mixture is limited to the area of their contact at extrusion of one component of the pipes with the simultaneous application of the second component of the annulus, resulting in an inhomogeneous, fragile insulating barrier. Due to this well-known method is ineffective.

The technical purpose of the proposal is to increase the efficiency of repair and isolation works by increasing the depth of coverage, homogeneous, dense mass, as well as due to an even distribution and mixing of injected components.

Technical problem is solved by the proposed method of isolation absorbing layers, including the descent of filling pipes in the interval isolation, consistent download on water filling pipes two components mixture until the full release of the first component in the annulus through the open end of the filling pipes and subsequent liquid.

What is new is that before descending to the interval isolation at casting tubes additionally set packer and the sleeve-cutter, consisting of a body with a through channel of circular cross-section with side opening and divider flow, casing, movable sleeve, despise filling pipe above interval isolation 30 m, consistently delivering two components mixture until the full release of the first component in the annulus through the open end of the filling pipes, produce landing packer, cut through the second component dosing pipes and simultaneously increase annulus pressure up to 2 MPa, with the possibility of movable sleeve and the release of the first component through the divider flow in the flow of the second component under pressure to cut through the components mixture, the first and second components produce portions in the amount from 3 to 4 at volumetric ratio of the components in increments from 1:4 to 1:1, respectively, starting with the ratio of 1:4 and ending at 1:1, after the release of the last portion of the components mixture of filling pipes cease to perform mixture liquid considering leaving in the borehole 20 m bridge of mixture, and as fluid using commodity oil.

The drawing is a way to isolate the absorbing layers. The essence of the method is as follows (see the drawing). Define the interval isolation 1. Determine the acceleration in the range of insulation of 1. In the casing 2 wells, fluid-filled killing, produce descent of filling pipes at a depth of 3 above interval isolation of 30 m with the established packer 4 (of various types) and the sleeve-valve 5. Bush-cutter consists of a housing 6, made in the form of cylinder having a eccentrically located through channel 7 of circular cross-section with side outlet 8 in the middle part, which is a flow divider 9, casing 10 installed outside the housing 6. Thus the case of the 6 with a casing 10 opposite side hole 8 form a cavity 11, inside of which is placed a mobile sleeve 12, which spring-loaded spring 13 up and blocks the hole of 8 in transport position (Fig. not shown). Spring 13 fixing the sliding sleeve 12, adjusted for the complete opening of the side hole 8 at a pressure of 2 MPa. Next, pick up a two-component mixture depending on what formulations are available. Choose the total amount of mixture of table 1, depending on the specific pick-up interval of isolation, which is installed during test-field works in the wells. Pick up the number of servings from 3 to 4 (depending on the injectivity of the interval insulation) and the ratio of the components in the portion is determined curing time mixture depending on the ratio of components.

Specific acceleration, m 3 /(h·MPa) within

Volume mixture, m 3

More than 6

The method can be applied two-component composition, consisting of the hardener and the main component cured with the heat release, for example:

- resin (TU 2228-006-48090685-2002) and a 10%aqueous a solution of sodium hydroxide;

- resin polymer composition «BARS» and hardener TU 2221-081-26161597-2011;

- silicon-organic product 119-296 (TU 2229-519-05763441-2009) and 6%hydrochloric acid;

- resin polymer composition «Б» and hardener TU 2221-081-26161597-2011 etc. curing Time of each portion depending on the volume ratio of components is given in table 2.

As the buffer and fluid using commodity oil.

Then pumped to water filling pipes 3 lightweight liquid, a buffer fluid, the first component, a buffer fluid, the second component mixture until the full release of the first component in the annulus is 14 through the open end of the filling pipe 3.

Volumetric ratio of the components

Curing time, h min

10%aqueous solution of sodium hydroxide: resin

Temperature mix at hardening 52°C

hardener: resin polymer composition «BARS»

Temperature mix at hardening 69°C

hardener: resin polymer composition «Б»

Temperature mix at hardening 34 C

6%hydrochloric acid: silicon-organic product 119-296

Produce landing packer 4. Use packer any famous designs, for example packer production type PSH. Further carry out second component dosing pipes, at the same time increases annulus pressure up to 2 MPa, with the first component press the sliding sleeve 12, compressing the spring 13, goes first to the hole 8, then through the flow divider 9 under pressure in the flow of the second component. Uniform distribution, mixing of injected components, and to obtain a homogenous mixture is ensured by a flow divider. the first and second components produce portions in the amount from 3 to 4 at volumetric ratio of the components in increments from 1:4 to 1:1, respectively, starting with the ratio of 1:4 and ending at 1:1. After the release of the last portion of the components mixture of filling pipes stop, mobile sleeve 12 action 13 spring back to its original position, and blocks the side hole 8, sealing annulus from the pipe. Thanks to sealed overlap of annular tube spaces does not occur free flow of fluid from the casting of pipes into the well annulus, or in the opposite direction. And carry out mixture liquid considering leaving in the borehole 20 m bridge of mixture.

Use as a buffer and liquid marketable oil reduces thinning of the components in the first and last portions, the most important part of mixture. For plugging mixtures on the basis of the majority of synthetic resins (, phenol-formaldehyde, ) and silicon products (119-296, AKOR-bn 102, the product 119-296) is characterized by a hardening of emitting heat, reduce curing times with increasing temperature, which leads to increased strength of the backfill stone produced from plugging mixtures on the basis of above-mentioned materials. components mixture begin with the ratio of components in the first portion of 1:4, which allows increasing the depth of coverage due to a longer curing time, a low viscosity mixture (100-150 MPa·s). Then the ratio of the components mixture in batches chosen in the range from 1:4 to 1:1. The last portion of forced components mixture in the ratio of the first and second components 1:1, respectively, that allows to achieve dense mass due to the rapid curing mixture. Consequently, the last portion of mixture in a ratio of components 1:1 is an additional catalyst curing previous by increasing the temperature mixture during curing. The number of servings choose between 3 and 4 (see table). Due to the disorganization of the annular space packer, movable bushing, and through that, and casting pipes are filled commodity oil, ensures the alignment of the reservoir and downhole pressures in the range of insulation. Thus, exposure mixture in the bottom hole zone occurs in the absence of differential pressure and, as a consequence, the filter.

An example of practical application.

At a depth of 894.8-895,6 m define the interval insulation, specific pick-up interval isolation - 3.18 m 3 /(h·MPa). At casting tubes set packer (packer TVs) and the sleeve-cutter. In the casing of a well, a fluid-filled killing, produce descent casting pipes in the interval 864,8 m (30 m above interval isolation). Bush-cutter consists of a housing 6, made in the form of cylinder having a eccentrically located through channel 7 of circular cross-section with side outlet 8 in the middle part, which is a flow divider 9, casing 10 installed outside the housing 6, building 6 with a casing 10 opposite side holes form a cavity 11, inside of which is placed movable bushing 12, which spring-loaded spring 13 up and blocks the hole of 8 in the transport position. Spring 13 fixing the sliding sleeve 12, adjusted for the complete opening of the side hole 8 if the pressure rises to 2 MPa from the original. Next, pick up a two-component mixture on the basis of resin and 10%of sodium hydroxide with a total volume of 10 m3 . Then pump cementing unit consistently delivering on water filling pipes 3 buffer fluid (oil commodity), 3 m 3 10%solution of caustic soda, a buffer fluid (oil commodity), 7 m 3 resin, until complete output 3 m 3 10%of sodium hydroxide in the annulus is 14 through the open end of the filling pipe 3. Produce landing packer 4. The cementing unit continue to resin for water filling pipes, the second cementing unit smoothly increase the annulus pressure up to 2 MPa, 10%aqueous solution of sodium hydroxide press the sliding sleeve 12, compresses the spring 13 and goes first to the hole 8, then through the flow divider 9 under pressure in a stream of resin. 10%of sodium hydroxide and resin is carried out using a two cementing units with three portions. First press through a portion of mix, starting with the component ratio of 1:4 (1 m 3 10%of sodium hydroxide and 4 m 3 resin), then a portion of mixture in the ratio of components 1:2 (1 m 3 10%of sodium hydroxide and 2 m 3 resin) and, to cut through the last bit of mixture in the ratio of components 1:1 (1 m 3 10%of sodium hydroxide and 1 m 3 resin). After the release of the last portion of mixture of filling pipes stop, mobile sleeve 12 by spring-13 returns to its original position, and blocks the side hole 8, sealing annulus from the pipe. Thanks to sealed overlap of annular tube spaces is not happening for the free flow of fluid from the casting of pipes into the well annulus, or in the opposite direction. Only then is forced mixture liquid dosing for pipes with regard to abandonment in the borehole 20 m bridge of mixture. Leave well on a response within 12 hours

Isolation method of absorbing layers, including the descent of filling pipes in the interval isolation, consistent download on water filling pipes two components mixture until the full release of the first component in the annulus through the open end of the filling pipes and subsequent liquid, characterized in that before the descent in the interval isolation at casting tubes additionally set packer and the sleeve-cutter, consisting of a body with a through channel of circular cross-section with side opening and baffle, casing, mobile sleeve, despise filling pipe above interval isolation 30 m, consistently delivering two components mixture until the full release of the first component in the annulus through the open end of the filling pipes, produce landing packer, continue to second component dosing pipes and simultaneously increase annulus pressure up to 2 MPa, with the possibility of movable sleeve and the release of the first component through the divider flow in the flow of the second component under pressure to cut through the components mixture, the first and second components produce portions in the amount from 3 to 4 at volumetric ratio of the components in increments from 1:4 to 1:1, respectively, starting with the ratio of 1:4 and ending at 1:1, after the release of the last portion of the components mixture of filling pipes cease to perform mixture liquid considering leaving in the borehole 20 m bridge of mixture, and as fluid using commodity oil.