RU2515740C1 - Construction finishing method for horizontal steam injector - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: in drilling, seepage-volume characteristics of the bed and their alteration over the borehole are defined, the borehole is divided into zones that differ in said characteristics by 1.5-1.6 times to select the filter performance separately for each zone and quantity of holes. In the filter openings under the plugs mesh filtering elements are installed, the production string is run in with the filter equipped with the behind-the-casing oil-swellable packers, which are set at boundaries of the areas with different seepage-volume characteristics. The production string is set up, the coil tubing is run in up to the well bottom, then it is transferred from the well bottom to the head with simultaneous pumping of polyacrylamide-based gel through it thus pouring the lower perimeter of the filter. When gel coagulation time is over the chemical reagent is injected through the coil tubing to the upper perimeter of the filter, the well is hold for the time of the plugs destruction in the filter openings in the upper perimeter of the filter, then reaction products are washed out.

EFFECT: improving quality of the stratum penetration, efficient impact of the working agent on the deposit.

3 dwg, 1 tbl

Description

The invention relates to the field of development of high-viscosity oil deposits and can be used for opening productive formations and their equipment in this interval with filters when completing the construction of steam injection horizontal wells, with the location of the injection horizontal well above the producing horizontal well.

A known method of installing a downhole filter (patent RU No. 2378495, IPC E21B 43/08, published in Bulletin No. 1 01/10/2010), which includes the descent into the drilled well of at least one downhole filter installed at the bottom of the casing and containing cutoffs plugs, and a centralizer is installed on each well filter before being lowered into the well, which is fixed on the well filter pipe that is free of the filter element. Packers are installed above the well filters, the number of which corresponds to the number of reservoirs. After the casing is lowered, the well is washed and packers are activated alternately from bottom to top, closing the central holes in the packer seats with a discharge element, for example, a ball, followed by pressure increase inside the casing and pumping cement into the annulus above the reservoir. After the cement has hardened, cementing plugs, packer seats and discharge elements are drilled, and all filter plugs are cut, while downhole filters are installed below the liner, which is connected through a disconnecting device to the transport string to deliver well filters in the liner to the well. After installing well filters with a liner in place, the transport string is undocked and removed from the well, and a check valve and shoe are installed below the well filters.

The disadvantages of this method are:

-first, a complex and labor-intensive technological process of its implementation;

and secondly, the long duration of the method, associated with the need to lower additional equipment into the well to destroy the sheared plugs, while some of the sheared plugs may remain intact.

There is also a known method for completing well construction (AS SU No. 1210507, IPC E21B 43/08, published December 12, 1987), which includes casing running into a drilled well equipped with a filter with plugs for holes made of material that is destroyed by chemical exposure installation of a production casing in a well with a filter located in the interval of the reservoir, plugging of a production casing with a filter, waiting for the hardening of grouting material, descent of the tubing string into the well, filling the well with a chemical with a chemical reagent, holding the well for the time of destruction of the plugs of the filter openings, injecting heat with variable pressure until the injected heat is connected to the formation fluid and cleaning the well from reaction products. The disadvantages of this method are:

- firstly, when plugging a production string with a filter, the space between the reservoir and the filtration channels in the filter ribs is blocked by grouting material, which reduces the productivity of the well;

- secondly, there is an inefficient opening of the reservoir due to the fact that the filter capacity does not take into account the permeability of the zones of the productive part of the well, opposite which this filter is located, which means that the main volume of the displacing agent pumped through the filter will "go" into zone with higher permeability.

The closest in technical essence is the method of completing the construction of a well (patent RU No. 2134341, IPC E21B 43/11, published in Bulletin No. 33 on December 9, 1999), including the descent of a production casing with a filter equipped with plugs in the holes from material that is destroyed by chemical exposure, installing a production casing in the well with a filter in the interval of the reservoir, plugging the production casing with a filter, waiting for the hardening of the grouting material, lowering into the well Hollogne tubing, filling the well with a chemical reagent to extract borehole decay time filter plugs hole injecting heat with variable pressure to it with a compound of the formation fluid and cleaning the well from the reaction products. According to the invention, a chemical reagent-soluble material is added to the grouting material in the filter interval to break the plugs of the filter openings, before filling the well with a chemical reagent, fill the tubing cavity with gas at an open annulus at the wellhead and push the well fluid to the bottom of the tubing pipes, and after filling the well with a chemical reagent, it is pushed with gas into the annulus, in the interval of installation of the filter, after which the annulus a nd the wellhead closed, and the subsequent injection of gas is carried out by the compressor. The disadvantages of this method are:

- firstly, the low quality of the opening of the reservoir, due to the fact that they plug both the production string and the filter, while behind the filter a cement stone is formed, worsening the hydrodynamic connection of the well with the reservoir;

secondly, the low efficiency of the development of a highly viscous oil deposit, due to the rapid watering of the produced products due to the fact that the filter has openings around the entire perimeter, so the injected steam through the openings located in the lower perimeter of the filter through the steam chamber will break into the trunk of a horizontal producing well located below, causing premature flooding of the extracted products from the reservoir;

thirdly, the imperfection of opening the reservoir, due to the fact that the number of holes made through the filter body, into which the plugs dissolving under the influence of a chemical reagent are installed, do not take into account the reservoir properties of the reservoir, which means that in areas with high filtration -capacitive characteristics of the reservoir, the filter capacity will be increased, and in areas with low filtration-capacitive characteristics of the reservoir, on the contrary, it will be limited, which will not allow to align the profile l injectivity deposits when injecting steam.

The technical objectives of the proposal are to improve the quality of the opening of a productive formation by a horizontal injection well in a highly viscous oil reservoir and to increase the efficiency of steam injection into a highly viscous oil reservoir with various filtration-and-reservoir characteristics of the reservoir by providing an optimal distribution of the injection volume throughout the horizontal wellbore and aligning the injectivity profile of the reservoir during injection couple.

The stated technical problems are solved by the method of completing the construction of a steam injection horizontal well, including drilling a trunk of a steam injection horizontal well, launching a production casing with a filter in the drilled hole, equipped with plugs from material that is destroyed by chemical exposure, installing a production casing in the well with the filter in the production interval formation, fixing the production string, lowering the pipe string into the well, filling kvazhiny chemical reagent wells exposure time to fracture filter plugs in the holes.

What is new is that in the process of drilling a steam injection horizontal well, the reservoir properties of the formation and their change in the horizontal well are determined, the wellbore is divided into zones that differ in reservoir properties by 1.5-1.6 times, depending on filtering capacity characteristics select the filtering capacity of the filter holes for each zone and the number of holes, then mesh filter elements are installed in the filter holes under the plugs s, the number of which corresponds to the number of holes in each zone, lowers a production casing with a filter equipped with annular water-swellable packers into a drilled steam injection horizontal well, and install them at the boundaries of zones with different filtration-capacitive characteristics, fasten the production casing, then lower the casing of flexible pipes to the bottom of the well, move it from the bottom to the mouth with simultaneous injection of a gel on the basis of polyacrylamide through the column of flexible pipes, which pour the lower perimeter of the filter, at the end of the coagulation time of the gel, the chemical reagent is pumped along the string of flexible pipes into the upper perimeter of the filter, the well is kept for the time of destruction of the plugs of the holes installed in the upper perimeter of the filter, and the reaction products are washed.

Figure 1, 2 and 3 schematically shows the order of implementation of the method.

The proposed method is carried out on deposits of highly viscous oil with the location of the injection horizontal well above the producing horizontal well.

The proposed method is as follows.

In the process of drilling a steam injection horizontal well, the filtration-capacitive characteristics are determined and their change within the reservoir 1 (Fig. 1) along the horizontal wellbore 2. The wellbore is divided into zones that differ in filtration-capacitive characteristics of 1.5-1.6 times.

For example, the length L of the barrel of a horizontal steam injection well 2 in the reservoir 1 is 400 m, the reservoir properties and their change along the trunk of the horizontal well 2 are defined as follows:

zone 3 '- permeability of 0.85 Darcy, length L ₁ = 120 m;

zone 3 ”- permeability of 1.3, Darcy, length L ₂ = 80 m (1.53 times relative to zone 3 ');

zone 3 '''- permeability 2.0 Darcy, length L ₃ = 60 m (1.54 times relative to zone 3 ");

zone 3 ”” - permeability 3.2 Darcy, length L ₄ = 140 m (1.6 times relative to zone 3 '').

The boundaries of the zones 3 ', 3 ”, 3''', 3” ”are the boundaries of lengths L ₁ , L ₂ , L ₃ , L ₄ , where the filtration-capacitive characteristics differ by 1.5-1.6 times.

Then, the throughput (pass-through area) of the openings 4, 4 ', 4 ”, ..., 4 ⁿ (shown in Fig. 1, conditionally) of the filter 5 is selected, for example, for a filter with a diameter of 168 mm separately for each zone 3', 3”, 3 ''', 3 ”” select the area of the bore openings depending on the filtration-capacitive characteristics. The selection of the area of the bore holes 4, 4 ', 4 ”, ..., 4 ^{n of the} filter 5 for each zone 3', 3”, 3 ”, 3” ”is carried out in any known manner, for example, as described in patent RU No. 2134341, IPC E21B 43/11, publ. in bull. No 33 on December 9, 1999

The filter 5 is made of casing with an outer diameter D equal to 168 mm and an inner diameter Dvf equal to 140.3 mm. The cross-sectional area of the 5 Fk filter is 154.5 cm ² .

Next, determine the number of holes 4, 4 ', 4 ”, ..., 4 ⁿ , performed in the filter 5 in each zone, according to the formula:

N _zi = (K ₁ / Ki) · (4 · Fk / П · do ² ) · L _i / k,

where K ₁ - the minimum permeability of the rocks in the zone of the productive part, opened by a horizontal well, Darcy;

Ki - permeability of rocks in the zone of the productive part, opened by a horizontal well, Darcy;

Fk is the cross-sectional area of the filter, cm ² ;

P = 3.14;

do - the bore diameter of the plugs 6, 6 ', 6 ”, ..., 6 ⁿ (fig. 2 shown conditionally) inserted into the holes 4, 4', 4”, ..., 4 ⁿ (FIG. 1) of the filter 5, cm , do = 1.2 cm;

L _i is the length of the zone of the productive part of the horizontal well;

k is the duty ratio, taking into account that the development of a highly viscous oil deposit is carried out through the upper perimeter of filter 2, we take k equal to 5.

Thus, substituting the values in the formula, we get the number of holes made in the filter 5 in each individual zone:

N _Z1 = (0.85 / 0.85) · (4-154.5 / 3.14-1.2 ² ) 120/5 = 3281 pcs.

N _Z2 = (0.85 / 1.3) · (4-154.5 / 3.14-1.2 ² ) 80/5 = 1430 pcs.

N _Z3 = (0.85 / 2.0) · (4-154.5 / 3.14-1.2 ² ) 60/5 = 697 pcs.

N _Z4 = (0.85 / 3.2) · (4-154.5 / 3.14-1.2 ² ) 140/5 = 1016 pcs.

The distance between the holes along the length of the filter 5 and the number of holes 4, 4 ', 4 ”, ..., 4 ⁿ along the perimeter of the filter is determined by calculation. For example, for a zone of length L ₂ with the number of holes N _Z2 1430 pcs. perform a radial row of holes, for example 8 holes with a diameter of 12 mm around the perimeter of the filter 5 and at a distance of 0, 45 m between the rows of radial holes, i.e. (80 m / 1430) · 8 = 0.45 m. Similarly, holes are made in the filter 5 in the remaining areas with lengths L ₁ , L ₃ , L ₄ .

All openings 4, 4 ', 4 ”, ..., 4 ^{n of} filter 5 are equipped with plugs 6, 6', 6”, ..., 6 ⁿ (conventionally shown in FIG. 2). For example, plugs 6, 6 ', 6 ”are pressed , ..., 6 ⁿ into the corresponding holes 4, 4 ', 4 ”, ..., 4 ^{n of the} filter 5. The plugs 6, 6', 6”, ..., 6 ⁿ are made in the form of plugs, for example, from a magnesium alloy that is destructible (soluble) ) a chemical reagent (eg hydrochloric acid) described in patent RU No. 2397316, IPC E21B 43/11, publ. 08/20/2010 in bull. Number 23.

Then, in the openings 4, 4 ', 4 ”, ..., 4 ⁿ (conventionally shown in FIGS. 1 and 2) of the filter 5, mesh filter elements 7 are installed under the plugs 6, the number of which corresponds to the number of openings 4, 4', 4”, ... , 4 ⁿ in zones 3 ', 3 ”, 3''', 3” ”.

The production casing 8 with a filter 5, equipped with annular water swellable packers 9 ′, 9 ″, 9 ″, ..., 9 ⁿ , is lowered into a drilled steam injection horizontal well 2 (FIG. 1) and they are installed at the boundaries of zones 3 ′, 3 ”, 3 ″’, 3 ″ ”of the reservoir 1. For example, three packers 9 ′, 9 ″, 9 ″ ″ are installed in zones 3 ′, 3 ″, 3 ″, 3 ″”.

As annular water swellable packers, for example, TAM brand FREECAP packers are used. These packers expand (swell), causing separation of layers after exposure to water vapor on their cuff, while the volume expansion of the packer reaches 200%.

The mesh filter elements 7 (see FIGS. 2 and 3) are made, for example, of porous metal fiber material (PMF) and porous sintered material (SL) made of 316L stainless steel or an alloy with a high nickel content, which allows them to withstand the toughest operating conditions in a horizontal production well. The mesh filter element 7 provides reliable and durable prevention of sand removal.

The production casing 8 is fastened (Fig. 1) in the horizontal injection well 1 by cementing 8 'and 8 ”in front of the filter 5 and behind it, respectively. A steam injection horizontal well 2 is left for a waiting time for solidification, for example, of cement mortar for 48 hours.

The elimination of cementing of filter 5 and the calculation of the area of the bore holes 4 of filter 5 for each zone 3 ', 3 ”, 3' '', 3” ”of the reservoir, depending on the permeability, improves the opening quality of the reservoir 1 and optimizes the selection of highly viscous oil from the reservoir .

Next, in the steam injection horizontal well 2 (Fig. 1), a string of flexible pipes 11, for example, with a diameter of 38.1 mm, is lowered to the bottom 10 to the bottom 10. Then it is moved from the bottom 10 to the mouth (Figs. 1, 2, 3 are not shown) with simultaneous injection through the flexible pipe 11 (Fig. 3) of the estimated volume of gel 12 based on polyacrylamide (PAA) or bipolymer.

For example, use DP9-8177 polyacrylamide according to TU 2458-010-70896713-2006, which is a modified polyacrylamide powder. Characteristics of polyacrylamide DP9-8177 are shown in the table.

Table Characteristics of Polyacrylamide DP9-8177 Name of indicator Value 1. Appearance White to cream powder 2. Mass fraction of the main substance,%, not less than 90.0 3. Bulk density, kg / m ³ 700-850

The estimated volume of gel 12, which is used to fill the lower filter perimeter, is taken equal to the volume of the filter’s internal space, divided into two, i.e. (Fk × L) / 2 = (154.5 × 10-4 m ² × 400 m) / 2 = 3.09 m ³ .

Gel 13 in a volume of 3.09 m pour the lower perimeter of the filter 5.

At the end of the coagulation time of gel 12, a chemical reagent, for example a 15% aqueous solution of hydrochloric acid 13, is pumped through a flexible pipe 11 into the upper perimeter of filter 5.

The estimated volume of acid 13 with which the upper perimeter of the filter 5 is poured is taken to be equal to the volume of the filter’s inner space divided into two, i.e. (Fk × L) / 2 = (154.5 × 10 ^-4 m ² × 400 m) / 2 = 3.09 m ³ .

The well 2 is kept for the duration of the reaction of a 15% aqueous solution of hydrochloric acid 13 with a magnesium alloy to break the plugs 6 in the holes 4 installed in the upper perimeter of the filter 5, for example, for 8 hours.

At the end of this time, the reaction products of hydrochloric acid with dissolved plugs 6 and gel 12 are washed out from the lower perimeter of filter 5 along its entire length. As a result, filter 5 (FIG. 3) has openings 4 (FIG. 1) only along the upper perimeter of filter 5 along its entire length (L = 400 m).

Next, a steam injection horizontal well is introduced into the development of a highly viscous oil deposit. Superheated water vapor is injected, for example, at a temperature of 220 ° C through a pipe string (not shown in FIGS. 1, 2, 3) through the mesh filter elements 7 (FIG. 3) installed in the openings 4 (FIG. 1) of the filter 5 in a steam injection horizontal well.

The holes in the filter are made along the upper perimeter, which eliminates the premature breakthrough of steam through the holes located in the lower perimeter of the filter, and prolongs the efficiency of the steam chamber and, as a result, the entire reservoir of highly viscous oil. As a result, the working agent is uniformly injected over the entire length of the filter, due to which there are no zones left in the high-viscosity oil reservoir that are not affected by water vapor, which makes it possible to equalize the injectivity profile of the high-viscosity oil reservoir when steam is injected into it and to uniformly produce high-viscosity oil in the reservoir .

The proposed method for completing the construction of a steam injection horizontal well allows to improve the quality of opening a productive formation by a horizontal well in a highly viscous oil reservoir and the effectiveness of the working agent on a highly viscous oil reservoir regardless of the permeability of its rocks.

Claims (1)

A method of completing the construction of a steam injection horizontal well, including drilling a trunk of a steam injection horizontal well, lowering a production casing with a filter into the drilled borehole, equipped with plugs from material that is destroyed by chemical exposure, installing a production casing in the well with a filter located in the interval of the reservoir, fixing the production columns, descent into the well of the pipe string, filling the well with a chemical reagent, holding the well life for the time of destruction of the plugs in the filter openings, characterized in that during the drilling of a steam injection horizontal well, the reservoir characteristics of the formation and their change along the horizontal well are determined, the wellbore is divided into zones that differ in filtration and capacitance characteristics of 1.5- 1.6 times, depending on the filtration-capacitive characteristics, the filter capacity of the filter holes for each zone and the number of holes are selected, then into the filter holes under plugs install mesh filter elements, the number of which corresponds to the number of holes in each zone, lower the production casing with a filter equipped with annular water swellable packers into a drilled steam injection horizontal well, and install them at the boundaries of zones with different filtration-capacitive characteristics, fasten the production casing, then lower a string of flexible pipes to the bottom of the well, move it from the bottom to the mouth with simultaneous pumping not flexible polyacrylamide-based gel tubes, which fill the lower filter perimeter, at the end of the coagulation time of the gel, the chemical is pumped along the flexible pipe string into the upper filter perimeter, the well is kept for the time of destruction of the plugs of the holes installed in the upper filter perimeter, and the reaction products are washed.

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