The way to develop heterogeneous permeability oil reservoirs

 

(57) Abstract:

The invention relates to the oil industry and can be used as a way to develop heterogeneous permeability oil reservoirs. The way to develop heterogeneous permeability oil reservoirs involves the injection into the reservoir fringes water, suspensions of water-soluble polymer and the suspension of dispersed filler in a liquid carrier in which the carrier fluid is an inert fluid, do not cause swelling of the dispersed filler and a water-soluble polymer, crude oil, petroleum distillates, petroleum products, organic solvents, with the injection of suspensions of water-soluble polymer and the suspension of dispersed filler is produced jointly or separately, and the contents dispersed filler in suspension choose within 4-10 wt.%. As a dispersed filler predominantly use superfine kaolin or wood flour. The technical result is to increase the efficiency of the development of heterogeneous permeability oil reservoir in the prevention or elimination of water breakthrough in high-permeability enthesopathies relates to the oil industry and can be used as a way to develop heterogeneous permeability oil reservoirs, providing an increase in oil production and limiting the inflow of formation water in production and injection wells.

There is a method of designing heterogeneous permeability oil reservoirs, including periodic pumping oil emulsion, gel-forming material based on water-soluble polymer and water [1]. The method allows to limit the pickup vodopostach intervals and connected to the development of poorly drained and stagnant zone of the oil reservoir. The disadvantages of the method are the need for periodic stopping of injection wells and mudding PPP (bottom-hole formation zone) well isolation reagents. The method is not effective in fractured reservoirs with conductivity.

There is a method of designing heterogeneous permeability oil reservoirs, including alternating injection into the reservoir fringes water and suspensions of water-soluble polymer in nevyzyvayut swelling inert liquid carrier, using the suspension containing the polymer of 0.01-20 wt. % [2] . The method provides a high-permeability mud vodopostach intervals due to the penetration of the polymer particles in the volume of the reservoir and subsequent nabemono the displacement of oil.

The main disadvantage of this method is low efficiency when used on highly permeable and fractured reservoirs, due to the migration of the polymer on the layer, therefore, the polymer does not provide crack isolation and areas of high conductivity. The disadvantages of the method are the low efficiency and low duration of stimulation when using the collectors with a pointed breakthroughs water and high-temperature collectors.

The closest technical solution, taken as a prototype, is a way to develop heterogeneous permeability oil reservoirs, including periodic injection into the reservoir of water with a salinity of at least 15 g/l and suspensions of water-soluble polymer and a dispersed filler in a liquid carrier, using the suspension containing the polymer of 0.05-1 and filler contents of 0.4-3.5 wt.% the reservoir also upload powder hydroxide of an alkali metal [2]. The method provides a high-permeability mud vodopostach intervals by forming a visco-plastic gel in the interaction of the polymer with the suspension of the hydroxide of an alkali metal and mineral water and next is lovanii on a monolithic low-permeability reservoirs, due to clogging of the PPP wells injected substances filtered in the form of a visco-plastic gel. The disadvantages of the method are the low efficiency and low duration of stimulation. This is due to low mechanical strength are formed in the layer of polymer gel and the migration of the polymer layer, resulting in not provided with sufficient insulation cracks and areas of high conductivity. The low efficiency of the method is also due to the fact that, on the one hand, high salinity water for injection suspension of the hydroxide of an alkali metal, and on the other hand, in such circumstances, there is a rapid degradation of the polymer and the destruction of the gel based on it.

The objective of the proposed technical solution is the increased efficiency of the development of nonuniform permeability oil reservoirs, increasing oil production and limiting the inflow of formation water in oil and injection wells.

This task is solved by the use of new methods, including the alternating injection of water, the suspension containing a water-soluble polymer, and the suspension containing dispersed filler. Motorstore is ulimately saturated high permeability intervals and cracks formation and connection to the development of low-permeability oil saturated intervals.

The essence of the invention is that the way to develop heterogeneous permeability oil reservoirs involves the injection into the reservoir fringes water, suspensions of water-soluble polymer and the suspension of dispersed particles in the carrier fluid, whereby as the carrier fluid is an inert fluid, do not cause swelling of the dispersed filler and a water-soluble polymer, with the injection of suspensions of water-soluble polymer and the suspension of dispersed filler is produced jointly or separately, and the contents dispersed filler in suspension choose within 4-10 wt.%.

As a dispersed filler use superfine kaolin or wood flour.

Salient features of the developed method are:

1. Use as a carrier fluid inert to vodorastvorimogo the polymer and the dispersed filler (not causing their swelling) hydrocarbon liquids - crude oil, petroleum distillates, refined petroleum products, organic solvents. Hydrocarbon liquids do not interact with water-soluble polymers and do not render them negativegoing in an inert hydrocarbon liquid is nedabujam condition, it penetrates into the volume of the reservoir and collateral most large pores and cracks. This provides a reduction in permeability intervals breakthrough of the water and prevents premature erosion of the polymer gel formed after injection of water-soluble polymer.

2. The use of dispersed filler content in the suspension of 4-10 wt. %. This dispersion of the filler in suspension allows you to effectively collaterality pores and cracks formation with different filtration characteristics. It is possible clogging of large natural (faults) and induced cracks (cracks after fracturing, behind-the-casing flows), and barring breakthroughs water for water deposits. Disperse the filler increases the viscosity of the initial carrier fluid, therefore, by adjusting its content, you can set the injected suspension of certain viscous properties, which will increase the efficiency of its stimulation.

3. Joint or separate injection of a suspension of water-soluble polymer and the suspension of dispersed filler. In the case of joint injection suspensions is provided by mixing a water-soluble polymer and a dispersed filler and posleduyushchii filler swell consistently, not swollen one component of the slurry is filtered in the formation intervals, partially kolmat swollen by another component of the suspension. Both options provide the most effective impact on highly permeable and fractured reservoirs. Concrete use one option or the other is determined by geological and physical parameters of the collector, the current state of development and injection wells.

4. Use as a dispersed filler predominantly fine-grained kaolin or wood flour. These fillers have a broad spectrum of dispersion and sufficient sediment stability in inert liquid carriers (oil, oil products) that allows you to upload them into the reservoir in the form of a suspension. Furthermore, these fillers effectively interact with water-soluble polymers adsorb them with the formation of various aggregates and structured gels resistant to erosion by water. In the layer after separation of the suspension of dispersed fillers this kind of swell in the water, which increases their clogging action. Disperse fillers are not prone to destructive influence of temperature and formation f may use a mixture of dispersed fillers, as well as other swelling (bentonite clay) and nanabhai fillers (e.g., lignin, carbon black, silica gel) that may slightly reduce clogging effect, but will increase the penetration depth of particles in the volume of the reservoir.

In General, the set of distinctive features provides the flow in the reservoir following processes. After injection into the reservoir rim of the suspension of dispersed filler is mudding the largest pores and cracks of the layer, and the particles of the filler being in nedabujam condition can penetrate deep into the volume of the reservoir. As the destruction of the slurry and pumping water filler particles swell. Subsequent injection of suspensions of water-soluble polymer and a new rim water is accompanied by the occurrence of fracture of the suspension, the swelling of the polymer interact with the particles of the dispersed filler and formation of single structured gel, preventing further filter the water on the treated interval. Further water injection will lead to the partial erosion of the polymer gel in the volume of the reservoir along the lines of water injection, which will warn of a sharp in-situ flow in high permeability zones. In igennem filtration characteristics and will cause a smaller cracks and the formation of new filtration channels. In the case of joint injection rims suspensions of water-soluble polymer and a dispersed filler or injection in a different sequence also occurs mudding processed intervals and redistribution of filtration flows to connection to the development of low-permeability oil saturated intervals. The mechanism proceeding in this case in the formation processes generally similar to those described above.

Regulation of fringe volumes injected slurries, dispersed filler content and its nature (swelling ability, dispersion, density), as well as the content of water-soluble polymer allows a wide range to adjust the nature of the stimulation, providing or alignment of the profile of water injection wells, or complete isolation of the individual intervals.

When using the method according to the prototype mudding highly permeable pores and cracks of the reservoir near the PPP wells and volume of the reservoir is only temporary, because the swelling of the polymer particles occurs in the presence of a hydroxide of an alkali metal and highly mineralized water that enhance degradation of the polymer. In addition, dissolution of the polymer is accompanied by the erosion of emerging stronger with increasing temperature and salinity of formation waters, that dramatically reduces the efficiency and duration of stimulation. In turn, this calls for increasing the number of treatments wells and expenses on them.

When using a new method such consequences affect in the least degree, because there is no negative effect of alkaline and saline environments on swelling the polymer, with the dissolution of the polymer in the injection of water occurs in the presence of inert particles dispersed filler that improves the stability of the formed polymer gel.

In the framework of the developed method using the following reagents:

water - soluble polymers include polyacrylamide, polyethylene oxide, carboxymethylcellulose, acetylcellulose and commercial products based on them, as well as other water-soluble polymers capable of forming aqueous solutions of high viscosity;

- dispersed fillers: superfine kaolin, wood flour, bentonite clay, fibrous wood flour, lignin, carbon black, silica (white carbon black), and so on;

- liquid-media: crude oil, petroleum distillates (gasoline solvent, kerosene, diesel fuel, fuel oil), oil products (nefras, butyl-benthological oil reservoirs used by alternating injection of water and rims suspensions of water-soluble polymer and particulate filler in an inert liquid carrier. The suspension of water-soluble polymer and a dispersed filler is injected separately or together.

The choice of specific quantities of water-soluble polymer, a dispersed filler, the content in the suspension, the volume of injected rims and the multiplicity of working well defined geological and physical parameters of the oil reservoir, the state of its development, current and planned performance well.

The alleged invention is illustrated by the following examples,

Example 1. In injection wells heterogeneous permeability oil reservoir with pickup 820 m3/day revealed the presence of high-permeability intervals, receiving more than 90% of the injected water. The average permeability of the reservoir is 50 MD, which indicates the presence of open fractures in the reservoir. In General, the plot works well characterized by a sharp increase in the water content. Downhole pump 10 m3the suspension containing 0.5 t polyacrylamide in an inert liquid carrier (crude oil with a density of 0,820 g/cm3). Then upload the rim of the water volume of 50 m3. Next upload 20 m3suspensions containing 1 ton of bentonite clay in the inert liquids the first mode water injection determine the percentage reduction in pickup and assess the need for additional injection of one or another of the suspension. Extra volume and rate of injection suspensions is determined from the conditions of achieving the required level of responsiveness, the number of injected dispersion of the filler and the water-soluble polymer reduced in 2-3 times. Then continue to water injection.

Example 2. In injection wells heterogeneous permeability oil reservoir with pickup 640 m3/day revealed the presence of high-permeability intervals, receiving 75% of the injected water. Previously well for a long time worked with the pickup 1550 m3/day, which indicates the presence of a layer of closed cracks and intervals of supercollector. In General, the plot works well characterized by high water content in crude production and low rates of production wells for oil. In the well pump 20 m3the suspension containing 2.5 tons of carboxymethyl cellulose in an inert liquid carrier (crude oil with a density of 0,785 g/cm), then pumped a slug of water. Then pumped into the well 30 m3the suspension containing 1.5 t bentonite clay and 0.3 tons of wood flour, using the same carrier fluid and determine the injectivity of the well after pumping rim water. Then squamscot wells and, if necessary, conduct additional injection rims suspensions with low content of dispersed filler and a water-soluble polymer, this allowed to increase the pressure of the injection rims suspensions and water.

Thus, the developed method allows to influence oil reservoirs with different geo-physical parameters and different indicators of wells to increase oil production and improve the current performance.

In practice, the method implemented using standard oilfield equipment by alternating injection of water and rims suspensions of water-soluble polymer and a dispersed filler.

Sources of information

1. Pat. RF 2094601, CL E 21 In 43/22, 1997

2. A. C. the USSR 1501597, CL E 21 In 43/22, 1991

3. Pat. RF 2136871, CL E 21 In 43/22, 1999

1. The way to develop heterogeneous permeability oil reservoirs, including injection into the reservoir fringes water, suspensions of water-soluble polymer and the suspension of dispersed particles in the carrier fluid, characterized in that as the carrier fluid is an inert fluid, do not cause swelling of the dispersed filler and a water-soluble polymer, crude oil, petroleum distillates, petroleum products, organic solvents, while Angelino, and the content of the dispersed filler in suspension choose within 4-10 wt.%.

2. The method according to p. 1, characterized in that the dispersed filler is used superfine kaolin or wood flour.

 

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2 tbl, 3 ex

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2 cl, 2 tbl

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