RU2455475C1 - Method of development of high-viscosity oil fields with strata of small thickness by way of cyclic injection of solvent and steam into single inclined wells - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: method of development of high-viscosity oil fields with strata of small thickness by way of cyclic injection of solvent and steam into single inclined wells includes drilling in productive bore of well uphill, location of tubing in this area with centralisers for solvent cyclic injection through them and production string with pumps for oil withdrawal, the maximum curve degree of well uphill is located in the stratum bottom section. The uphill development is performed with ascent angle not less than 5-8° of stratum bottom, the backwall of the uphill is located below the roof not less than 2 m. Before descending of the string that is thermally insulated the well uphill is equipped by filter with two opened zones in the beginning and the end of this area, tubular annulus between the filter and string and between the opened zones is isolated by packer. The pump is located in the bottom area of productive stratum higher than the opened zone in the beginning of the well uphill, but lower than the backwall of the well uphill. The solvent and steam are pumped by turns into the roof of the stratum through the opened zone in the end of well uphill, there performed is a holding for heat distribution in the stratum, then the fluid is withdrawn by pump.

EFFECT: increase of efficiency of development of high-viscosity and extra-viscosity oil fields with strata of small thickness.

2 cl, 1 ex, 1 dwg

Description

The invention relates to the oil industry, to thermal methods for oil or bitumen production from a single directional well.

A known method of in-situ production of bitumen and heavy oil by cyclic injection of solvent (patent CA 2349234, IPC ЕВВ 43/22, publ. 05.31.2001), including drilling a horizontal well and injecting a solvent in the bottomhole zone of the well, which reduces the viscosity of the oil, while obtaining reservoir pressure in excess of the pressure of the transition of the liquid phase of the solvent into steam. The hydraulic effect of a liquid solvent on the rock during the injection process allows you to expand the pore space and creates additional elastic energy by compressing the gas-liquid formation fluid. When the reservoir pressure decreases below the pressure of the transition of the liquid phase into the vapor due to volume expansion of the vapor phase, formation hydrocarbons are displaced from the reservoir into the horizontal perforated zone of the horizontal well, with which the pump pumps the liquid to the surface.

The method has the following disadvantages:

- structural complexity of the launched underground equipment - the pump is located at the end of the horizontal perforated section of the liner, above which two packers are installed alternately;

- low coverage of the productive formation by the action of a solvent, since the solvent is injected without additional heating of the formation and at reservoir temperature as reservoir pressure decreases, not all solvent from the liquid passes into the vapor phase.

The closest in technical essence to the proposed method is a method for developing deposits of highly viscous and ultra-high viscosity oils (RF Patent No. 2387818, IPC ЕВВ 43/24, publ. 04/27/2010. Bull. No. 12). According to the invention, comprising injecting steam into the formation, heating the formation with the creation of a steam chamber, joint injection of steam and a hydrocarbon solvent and product selection, a mixture of hydrocarbons of the limiting aliphatic and aromatic series, the main component of which is benzene, is used as the hydrocarbon solvent, and the combined injection of steam and hydrocarbon the solvent is carried out after reaching a temperature in the steam chamber of not less than the phase transition temperature of the mixture of steam of a hydrocarbon solvent .

The disadvantage of the invention is the need to drill two parallel, located one above the other wells, which at small thicknesses of the reservoir is a difficult task.

The technical task of this proposal is to increase the efficiency of the development of high-viscosity and super-viscous oil fields with small-thickness formations using single-drilled wells by the method of cyclic injection of solvent and steam into the reservoir.

The problem is solved by the method of developing high-viscosity oil fields with small thicknesses by cyclic injection of solvent and steam into single directional wells, including drilling in the productive wellbore of the ascending section of the well, placement of tubing string in this section with centralizers for cyclic injection hydrocarbon solvent and heat carrier through them and production casing with a pump for oil selection.

New is that the maximum angle of curvature of the ascending section of the well is located in the bottom of the formation, the wiring of the ascending section is carried out with an elevation angle of at least 5-8 ° from the bottom of the formation, the bottom of the ascending section is located below the roof for at least 2 m, and before the descent of the pipe string which are thermally insulated, the upstream section of the well is equipped with a filter with two open areas at the beginning and end of this section, and the annulus between the filter and the pipe string and between the open areas is isolated with a packer, this pump is located within the bottom part of the reservoir, above the open zone at the beginning of the ascending section of the well, but below the bottom of the ascending section of the well, the solvent and steam are pumped alternately into the roofing part of the formation through the exposed area at the end of the ascending section of the well, exposure is carried out to distribute heat to formation, then start the selection of fluid pump.

New is that hydrocarbon solvent is injected before steam is injected into the roof of the formation with a pressure sufficient to expand the pore space of the reservoir rock and compress the formation fluid.

After alternate injections of the calculated quantities of solvent and heat carrier, the well stops for aging, after the temperature and pressure decrease (the thermodynamic reservoir conditions should be within the steady state of the bulk of the injected solvent in the vapor phase), the well is put to fluid selection.

The drawing shows a diagram of a directional well in the context of an oil reservoir.

The method is implemented as follows.

Oblique drilling of the wellbore 1 is carried out under the production string 2 to a depth below the roof 3 of the formation 4 at least 2 m. The production string 2 is lowered, the annulus 5 is cemented. The smaller diameter of the bit is used to drill the ascending section 6 of the wellbore along an inclined directional ascending path, when this maximum angle of curvature is located in the bottom part 7 of the reservoir 4, then the wiring of the ascending section 6 of the wellbore 1 is carried out with an angle of elevation of at least 5-8 ° from the bottom 7 to roof 3 with installation of a bottom hole 8 of the well at a distance of at least 2 m vertically below the roof of the reservoir 4. Filter 9 is lowered with two open perforation zones 10, 10 'at the end and beginning of the ascending section of the well 6. Heat-insulated tubing 11 equipped with heat-resistant are lowered packer 12, uncoupling the upstream section of the well with two exposed zones, which are located at the beginning and end of this section 6. Above the opened perforation zone 10, but below the bottom 8 (to obtain the maximum influx of heated oil due to gravity s forces) descends electric centrifugal pump 13 in tubing 14 with a thermocouple cable (not specified in the drawing) to control the temperature at the pump intake. The slope of the ascending section 6 of wellbore 1 from the roof 3 to the sole 6 of formation 4 allows heated oil to flow to the lower exposed zone 10 of wellbore under the influence of gravitational forces 1. The use of heat-insulated tubing 11 reduces the heat loss of the injected steam, and the absence of heating of the outer surface of the tubing 11 the ability to use an electric centrifugal pump 13 of a serial type, which is in permissible temperature operating conditions during the injection of steam into the reservoir 4. The calculated quantity of solvent and coolant to the remote exposed zone 10 'along the column of heat-insulated tubing 11. A certain period of time is maintained for heat distribution in the reservoir 4 and the fluid is pumped by pump 13 through the tubing 14 to an acceptable temperature, pressure and flow rate, after which the solvent and steam injection cycle the column of insulated pipes 11 is repeated.

Concrete example

A well with an ascending section 6 was drilled in a section of a highly viscous oil reservoir in formation 4. It was arranged. The reservoir and thermal properties of the discovered reservoir were clarified. 4. The reservoir development area where the claimed technology was tested had geometric dimensions of 200 × 100 × 15 m. The average thickness of the formation is 15 m.

The directional well 1 was alternately provided with a supply of solvent and steam. After warming up and creating the conditions for the transition of the solvent to the vapor phase, the steam supply to the well 1 was stopped and, after soaking, the pump began to withdraw liquid by pump 13 via tubing 14.

For the comparison base, the option was adopted using a single horizontal well with a horizontal bore length of 200 m. The results showed that the efficiency of the proposed method is higher: the maximum oil recovery coefficient is 7% higher, the maximum oil production rate obtained was 9 tons / day versus 2 tons / day when using horizontal in the vertical plane of wells.

Thus, in contrast to the application of the technology of cold cyclic injection of solvent into horizontal wells, the proposed method for developing high-viscosity oil fields with small thicknesses by the method of cyclic injection of solvent and steam into single directional wells allows to reduce material and energy costs and to obtain a higher rate of fluid withdrawal from wells. These results are achieved through the use of heat-insulated tubing, a special well profile, alternate injection of solvent and steam, and a mechanized production method.

Claims (2)

1. A method of developing highly viscous oil fields with small thicknesses by the method of cyclic injection of solvent and steam into single directional wells, including drilling an upstream section of the well in a production well, placement of tubing strings in this section with centralizers for cyclic solvent injection through them, and production casing with a pump for oil extraction, characterized in that the maximum angle of curvature of the ascending section of the well is located in the plantar that, the ascending section is wired with an elevation angle of at least 5-8 ° from the bottom of the formation, the bottom of the ascending section is located below the roof for at least 2 m and before the descent of the pipe string that is thermally insulated, the ascending section of the well is equipped with a filter with two open zones at the beginning and the end of this section, and the annular space between the filter and the pipe string and between the exposed areas is isolated by a packer, while the pump is located within the bottom part of the reservoir, above the opened area at the beginning of the ascending part of the well, but below the bottom of the ascending section of the well, the solvent and steam are pumped alternately into the roofing part of the formation through the exposed zone at the end of the ascending section of the well, exposure is carried out to distribute heat in the formation, then the pump will begin to draw fluid. 2. The method according to claim 1, characterized in that the cyclic injection of the hydrocarbon solvent is carried out alternately before the injection of steam into the roofing of the formation with a pressure sufficient to expand the pore space of the reservoir rock and compress the formation fluid.