Compound method for oil displacement out of bed by water-alternated-gas injection with use of well-head ejectors

FIELD: oil and gas industry.

SUBSTANCE: invention pertains to oil and gas producing industry and namely to methods of oil recovery improvement and simulation of oil and gas production in injection producing oil and gas wells with terrigenous and carbonate reservoirs. The concept of the invention is as follows: method for oil displacement out of bed by water-alternated-gas injection with use of well-head ejectors is characterised by installation of well-head ejector with preset ratio of nozzle and diffuser at injection line of an injection well connected to annular space of production wells or a group of production wells at their pad; through this well-head ejector sediment-generating compound is pumped into the tube side of production tubing at first, then water is injected for associated gas injection and water-gas mixture is formed. At that pressure is decreased in annular space of the production well.

EFFECT: increasing efficiency of the method due to input profile balancing of injection wells with heterogeneous beds and channels with low filtration resistance and at the same improving operating mode of production wells.

5 cl, 2 ex, 1 dwg

The invention relates to the oil and gas industry, namely to methods of enhanced oil recovery and enhanced recovery of oil and gas in the discharge producing oil and gas wells as of terrigenous and carbonate reservoirs. This method aligns the profile of the injection well with heterogeneous, unevenly produced layers with the presence of channels with low filtration resistance (NSF). The present invention is a combination of physico-chemical methods of enhanced oil recovery, water-gas stimulation and increased stimulation of production wells.

In Russia critical situation with the oil recovery factor (next of KIN), which in 1960 was equal to 51%, in 2000, decreased to 35%, and to date has declined to 27-28%, which is one of the lowest levels in the world. In addition, the development of domestic deposits in recent times brighter is the problem of burning in the fields of the associated petroleum gas (APG). Based on domestic and foreign experience, we proposed a combined method of injection into the injection well, usedcolors compositions with subsequent water-gas effects while using associated gas producing with vain on the Bush, will significantly increase oil recovery heterogeneous petroleum reservoirs.

There is a method of enhancing oil recovery and regulation of the development of oil fields by flooding, including periodic injection of an aqueous solution of the polymer and the suspension of dispersed particles (see RF patent №2090746, CL EV 43/22, 1997). The method provides an increase in oil recovery due to clogging of highly water-producing zones of the formation. The disadvantages of this method are the low efficiency of field development with the zonal heterogeneity and oil with high viscosity, due to the shallow depth filtration of dispersed particles in the volume of the reservoir and the low viscosity of the injected polymer solution. The main disadvantage of this method is that for hard formations with pronounced heterogeneity with artificial or natural cracks needed injection of large amounts of fringes of polymer solution and a suspension of dispersed particles, in addition, at the slightest deviation from the technology is the deposition of clay particles on the bottom of a well. The method is ineffective due to lack of increase of residual resistance factor in fractured zones of the reservoir, so the short-term with low oil, low coefficient the displacement. For additional displacement of residual oil in this way is not applicable water effects and are not used in a manner associated gas utilization.

There is also known a method of utilization of associated gas to create a vacuum in the annulus of the production well equipped with ECP. Used a combined scheme with the installation of the jet pump ejector at the wellhead, manifold x-Mas tree after the check valve in the discharge string of x-Mas tree (Device for operation of the wells. Utility model RU 50596 U1. Author Mikheev P.E. Application No. 2005121484/22 from 11.07.2005,).

The basis in this way Mikheeva P.E. is the creation of a vacuum in the annular space energy with jet pump-ejector mounted in the receiving reservoir of the fountain of the valve after the check valve in the discharge string of x-Mas tree. When working ESP downhole fluid in the mouth, flowing through the jet pump creates a vacuum, which through the open valve sucks the gas from the annulus of the well. The negative pressure in the casing-formation annulus allows to increase the output of gas from the well fluid and selecting it from the separator pump that improves absorption and increases the flow of well fluid from the reservoir, which generally increases the et efficiency of the pumping installation. This method is an effective technical solution in the operation of wells ESP with the use of ejector for sampling gas from the annulus from the same well. In addition, to create the necessary vacuum in the annular space you want to create on the ejector high fluid velocity and pressure differentials, and any choke restriction on the mouth leads to increasing pressure on the pad and reduce the operating time of the pump. The main drawback of this method is that it is not a method of enhanced oil recovery, and a method of stimulation, and production optimization of single wells. There is no impact on the formation of sediment-gel-making compositions, water-gas mixtures, there is no utilization of associated gas, no increase of displacement ratio and coverage for non-homogeneous layer.

There is also known a method of displacing oil from the reservoir (patent No. 2170814, EV 43/20, application number: 99121601/03. Publication date: 20.07.2001. Authors: Romanov G.V.; Khisamov R.S.; Muslimov, BC). Of all the ways this is the closest technical solution, analogue and prototype for our proposed method for the enhanced recovery of heterogeneous petroleum reservoirs. In this way pumped water through the annular space of the injection wells and gas through its tubing. On the bottom hole on asout the ejection of water-gas mixture. Displace oil toward producing wells. Ejector device mounted on the bottom of injection well and with a check valve at the point of introduction of gas in the ejector device. Line tubing injection wells associate and identify with the annular space of wells for the disposal of their associated gas. In injection well periodically add a surfactant with a concentration of about 0.5-1.1%. After actuation of the check valve ejector device carry out the acid treatment of oil using acid forming soluble salts upon contact with the carbonate skeleton of the breed. Despite the originality of the solutions this method has several disadvantages. The disadvantage of this method is that the ejector is on the bottom of injection wells and to correct any faults require repair of wells with pre-lifting operations. The complexity of maintenance and the inability to regulate the operation of the ejector, there is no possibility of controlling fluid flow and pressure. Water injection is made in annular space with limited pressure above the pressure of the pressurization of the production string, this limits the selection of candidate wells. The injection of water through the annular space creates the danger of infringement of EC is operating columns, accelerates the corrosion process, reduced reliability of tightness. This method does not pumping usedcolors compositions in heterogeneous formations with natural and artificial fractures, respectively, will be below the oil recovery factor.

Unlike the prototype, the technical result of the proposed technical solution is to align the profile of the injection well prior injection of usedcolors compositions washed with blocking high permeability channels, the subsequent injection and displacement through the mouth of the ejector gas mixture with additional moviesanal residual oil. Associated gas for the water-gas mixture is drawn through the jet pump ejector Struble producing wells in the Bush. This method simultaneously solves the problem of preservation, utilization of resources associated with gas wells and increase oil recovery.

The technical result is achieved by the fact that in the complex method of displacing oil from the reservoir water effects with the use of estuarine ejectors on the injection line injection wells associated with the annular space of the production well or group of wells in their hive, set with a given ratio of nozzle sizes and diff the Zora mouth ejector, through which the tube space of tubing pre-fetch sedimentation composition, and then water for injection of associated gas and formation water-gas mixture, thus reducing the pressure in the annulus of the production well. As usedcolors compositions can be applied formulations of water - based sodium silicate or polymers, viscoelastic, or gelling or precipitation forming compositions. In addition, revision, or maintenance of the wellhead ejector produce without lifting underground equipment and attraction of repair crews. If necessary, use hydrodynamic injection control methods, non-stationary cyclic flooding, and the injection of chemical solutions, acids, solvents produced through a lubricator valve.

In the present method at the same time is the alignment of the injection wells with a subsequent increase oil recovery and increase productivity of production with subsequent stimulation. For enhanced oil recovery with alignment profile pick is pumped into the reservoir consistently sediment-gel-making structures and then through the mouth of the jet pump ejector water-gas mixture. Injection through the ejector into the injection well of usedcarloanrefinancing and water-gas mixture is produced in the tube space, through the tubing into the formation, maintenance column protected with a packer. Wellhead ejector for water-gas mixture is used, associated gas from Struble not only one of the selected wells with ESP, usgn, but from a group of wells in the Bush. The decrease in annulus pressure for a group of wells in the Bush leads to decrease manifold pressure on the oil-field, and, as a consequence, this leads to an increase of the flow rates of these wells. Sediment-gel-making structures are more resistant to erosion and destruction of temperatures, securely block scoured channels and cracks, staying active, participate in the displacement of residual oil. To increase the injectivity of descent devices for GIS for injection of chemical solutions, acids, solvents are not required change of wellhead piping and disassembly of the ejector, all work can be made through the lubricator valve.

The drawing shows a diagram of the binding of injection wells with wellhead ejector and the annular space of the production well, the numbers denote: 1 - lubricator valve; 2 - pressure gauge; 3 - buffer valve; 4 - manifoldly valve; 5 - jet pump ejector; 6 - Central valve; 7 - annular valve; 8 - line injection annulus gas; 9 - cable CRBC with cable entry; 10 - fitting; 11 - return valve; 12 - tube data strubel the space of the production well; 13 - annulus valve of the production well; 14 - valve on the gas line.

The method is as follows.

The jet pump ejector installed on the discharge line of wellhead x-Mas tree injection wells. The ejector is a downhole device, the outer diameter of which does not exceed 0.1 m, the total length of not more than 0.4 m, all components and parts located inside the housing have standard pipe threads and couplings. Pre-produce sequential injection of usedcolors compositions in the injection well for the injectivity profile alignment. Then produce the displacement of water through the eductor to create a vacuum in the vent line from satrupa producing wells. Annular gas wells take with jet pump-ejector, mixed with water and pumped into the reservoir. Subsequent injection and displacement through the mouth of the ejector water-gas mixture and produces a displacement of residual oil.

As usedcolors compositions can be used in the compositions of the water - based sodium silicate or polymers or viscoelastic, or gelling, or sedimentation system. Sediment-gel-making structures are more resistant to erosion and destruction of temperatures, securely block scoured channels and cracks, remaining ACC is mportant, participate in the displacement of residual oil. The amount of associated gas and its concentration in the mixture of water depends on the capacity of the well and pressure injection. To prove compliance of the claimed invention described specific examples of practical testing of the method. Work conducted in the fields of Western Siberia: in the Samotlor and Orekhovo-ermakovskom.

Example 1. Practical application of the proposed method produced on the Bush 1241 Samotlor oil field. Estuarine jet pump ejector was installed at the mouth of the injection wells 31314 instead wellhead fitting. For injection annulus gas selected wells equipped with ESP 37139, reservoir AV-2. Well 31314 before the experiment had the pickup 250 m³/d when the diameter of the pieces of 3.5 mm, with Rneg=9.7 MPa, to fitting and after 5.0 MPa. Well 37139 worked parameters Ndin=1400 m, the flow rate of 60 m³/day, annulus pressure 1.6 MPa. After the ejector at the mouth of the injection well, the injection line through a check valve made the line tie on the well annulus 37139. Mouth harness wells 31314 and 37139 for HBV. In the ejector installed nozzle and diffuser in a ratio of 3.7×5,6 and ran well. In the injection water through the mouth of the ejector pickup wells was 220 m³/day, pressure on I is de 10 MPa, after 4 MPa. Annular pressure wells 37139 decreased from 1.6 MPa to 0.5 MPa. The dynamic level in the well is increased by 200 meters, increased the rate of 15 m³/day, and the total number of injected gas was in the range of 1500 m³/day. The results of practical trials have confirmed the effectiveness and efficiency of the proposed method.

Example 2. The following tests were performed on Orekhovo-ermakovskom field in the injection hole 574 and mining 2400. From production data on the production wells 2400 through the use of jet pump-ejector pressure in the annulus decreased from 2.2 MPa to 0.2 MPa, increased flow rate of fluid with 80 m³/day up to 114 m³/day, increased oil production from 14 tonnes to 18 tonnes at a dynamic level of 1300 meters. For the period of tests on wells from may to November 2011, the efficiency has not changed, special complications, gidratoobrazovaniya on the injection line is not installed. The success of the proposed technology for utilization of associated gas from the annulus of the borehole with the subsequent injection of HCV in injection wells with wellhead jet pump-ejector is confirmed by the example of the two wells.

1. Comprehensive method for the displacement of oil from the reservoir water effects with the use of estuarine ejectors, characterized in that the on the injection line injection wells, associated with the annular space of the production well or group of wells in their hive, set with a given ratio of the nozzle and diffuser mouth ejector, through which the tube space of tubing pre-fetch sedimentation composition, and then water for injection of associated gas and formation water-gas mixture, thus reducing the pressure in the annulus of the production well.

2. The method according to claim 1, characterized in that as usedcolors compositions the compositions are used water - based sodium silicate or polymers, viscoelastic, or gelling or precipitation forming compositions.

3. The method according to claim 1, characterized in that revision or maintenance of wellhead ejector produce without lifting underground equipment and attraction of repair crews.

4. The method according to claim 1, characterized in that, if necessary, using hydrodynamic injection control methods, non-stationary cyclic flooding.

5. The method according to claim 1, characterized in that the injection of chemical solutions, acids, solvents produced through a lubricator valve.