RU2506417C1 - Development method of high-viscosity oil deposit - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil producing industry. In development method of high-viscosity oil deposit that includes drilling of vertical injection wells and horizontal directional producers, pumping of operating fluid through injection wells and oil withdrawal through producers, determination of oil-water contact (OWC) level the horizontal directional producer is drilled from mouth to downhole at the level at least per 2-3 m higher than OWC level; vertical injection well is drilled so that its downhole is located over producer downhole per 5-8 m. The producer is perforated along it hole length while the vertical injection well is perforated in the stratum area in direction towards the producer mouth. Stage by stage as operating fluid breaks through or water cut exceeds 95% downhole of the horizontal directional producer is cut off above the breakthrough or watercut area and the area of injection well penetration is cut off from below per 1/3 - 1/2 of its whole length. When production of the production area is completed the mouth of horizontal directional producer is placed under pressure of operating fluid.

EFFECT: working efficiency in the deposit with inclined oil-water contact, reducing watercut rate of the product extracted from the deposit, excluding breakthrough of heat carrier to the producer with simultaneous reduction of expenditures as construction of additional injection well is excluded.

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Description

The proposal relates to the oil industry, and in particular to methods for developing a reservoir of high viscosity oil.

There is a known method of developing a highly viscous oil deposit (RF patent No. 2062865, IPC ЕВВ 43/20, published in Bull. No. 36 dated 06/27/1996), according to which vertical injection and horizontal producing wells are drilled on a highly viscous oil deposit. The coolant is pumped through the injection wells and at the same time periodically through horizontal wells until the coolant breaks through to the vertical production wells. After the coolant breakthrough, a displacing agent is pumped through the injection wells, and sand and formation fluid are selected through horizontal wells.

The disadvantage of this method is that it does not allow to develop an oil reservoir with the achievement of high oil recovery. A quick breakthrough of the coolant from the injection well into the producing well is likely, which reduces its efficiency and increases implementation costs.

The closest in technical essence and the achieved result is a method for developing a highly viscous oil deposit (patent RU No. 2334095, IPC ЕВВ 43/24, published on September 20, 2008), including drilling vertical injection wells and horizontal production wells, pumping a working agent through injection wells and selection of oil through production wells. The horizontal wellbore of the producing well is carried out at 1.5-2.5 m above the bottom of the reservoir and is perforated. Above the horizontal well of the producing well, 3.5-4.5 m is placed the bottom of the vertical injection well, perforated in the range of 0.5-1.5 m from the bottom. A vertical injection well is placed from a vertical wellbore of a producing well at a distance greater than 2/3 of the length of the horizontal section of the producing well, up to the end of the horizontal wellbore, with steam alternating with air being used as an agent.

The disadvantage of this method is the likelihood of a quick breakthrough of the coolant due to the small distance between the bottom of the producing and injection wells (3.5- (3.5-4.5 m). In this regard, high costs and low efficiency. The method is not suitable for development deposits with an inclined oil-water contact.

The technical objectives of the method are operability in a reservoir with an inclined oil-water contact, a decrease in the percentage of water cut of produced products from the reservoir, elimination of a breakthrough of the coolant in the producing well, cost reduction for the exclusion of the construction of an additional injection well.

The technical problem is solved by the method of developing a highly viscous oil deposit, including the drilling of vertical injection wells and horizontal production wells, pumping a working agent through injection wells and taking oil through production wells.

New is that they determine the level of water-oil contact (OWC), producing an inclined horizontal well from the mouth to the bottom of the hole with a location of at least 2-3 m above the level of the OWC, a vertical injection well is drilled with the bottom position above the bottom of the producing well 5 -8 m, perforate the production well along the entire length of the inclined section, the injection vertical well is perforated in the formation zone in the direction of the mouth of the production well, in stages, as the working agent breaks or the product is flooded e 95% of the bottom of the producing horizontal well is cut off above the breakthrough or flooding zone, and the opening area of the injection well is cut from the bottom by 1 / 3-1 / 2 of its entire length; when the entire developed zone is developed, the mouth of the producing inclined horizontal well is transferred to pump the working agent .

The drawing shows a layout of a vertical injection well and an inclined horizontal production well.

The method of developing deposits of high viscosity oil is as follows.

In the reservoir 1 determine the level of water-oil contact (WOC) 2, if the level of WOC inclined 2 ', then determine its angle of inclination. Next, they drill and equip a horizontally-inclined production well 3 with a bottom face above the level of BHK 2 by at least 2-3 m, through which the production of formation 1 will go. Perforate the well 3 throughout the bore. In the case of developing a reservoir with an inclined level of KSS T, an inclined horizontal well 3 is drilled above the level of KSS T with a distance of at least 2-3 m from it. Next, a vertical injection well 4 is drilled with a bottom location 5-8 m above the bottom horizontally inclined production well 3. After equipping a vertical well 4, a working agent is pumped through it. As a working agent, steam is used, for example, with a temperature of 180-250 ° C and a dryness of 0.8 units. To reduce heat loss and create a steam chamber above the horizontal horizontal well 3, the vertical injection well 4 is perforated in the direction of the mouth of the horizontal horizontal well 3. Then, according to the method, step by step as the coolant breaks through or reaches the water cut percentage above 95%, the bottom of the producing horizontal horizontal well 4 cut off above the breakthrough or flooding zone. As an isolation of the flooded section of the wellbore or a breakthrough of the coolant into it, various deaf packers or plugging compositions can be used, as well as, for example, clay or cement mortar. In case of timely isolation of the problem area, it is possible to almost completely eliminate the problem of breakthrough of the coolant, thereby achieving savings when injecting the working agent, and also to avoid the pressure drop, which gives a high flow of production to the production well. The opening area of the injection well is cut off from the bottom by 1 / 3-1 / 2 of its entire length, for example, by deaf packers or plugging compositions. This decision is caused by the fact that with a small (5-8 m) distance between the faces of producing 3 and injection 4 wells, production can be achieved at an earlier stage of formation 1 operation, but a breakthrough of the working agent is also possible. As a result, after heating the inter-well zone, the bottom of the bottom of injection well 4 needs to be isolated, then the working agent will be injected into the upper interval of the productive formation 1, and thereby the formed vapor chamber above the production inclined horizontal well 3 will push the product out of the upper section of the formation 1, also such a solution gives a lesser probability of a breakthrough of the working agent. When developing the entire developed zone, the mouth of the producing inclined horizontal well 3 is transferred under injection of the working agent.

The proposed method for developing a highly viscous oil reservoir was implemented at the field with the following geological and physical characteristics:

The average depth of the object is 85 m.

The average total thickness of the reservoir is 26 m.

VNK level - 84 m.

The value of the initial reservoir pressure is 0.45 MPa.

The initial reservoir temperature is 8 ° C.

The density coefficient of oil in reservoir conditions is 0.965 kg / m.

The coefficient of dynamic viscosity of oil in reservoir conditions is 12000 MPa · s.

The coefficient of dynamic viscosity of water in reservoir conditions is 1.3 MPa · s.

The average core permeability in the reservoir is 1500 μm.

The value of the average core porosity in the reservoir is 0.08 units.

Above the inclined level of VNK T at a distance of 2.5 m, an inclined horizontal well 3 was constructed with a length of an inclined horizontal section of 150 m, which was perforated with a PGM-120 hydromechanical perforator along its entire length. We built a vertical well 4 with a bottom position 6.8 m above the bottom of well 3. In well 4, layer 1 was re-opened at a length of 12 m with a one-sided hydromechanical perforator PGM-0-120 towards the wellhead 3, oriented in the well using geophysical navigation equipment . When the coolant breakthrough, the bottom-hole part of well 3 at a distance of 40 m from the bottom was filled with a clay solution. At the same time, vertical well 4 at a distance of 5 m from the bottom was filled with cement mortar, completely eliminating the possibility of a coolant breaking from well 4 into well 3. Wells 3 and 4 were continued to operate until production was completely flooded (above 95%) in production well 3, which was transferred under injection of the working agent. As a result, the use of the proposed method made it possible to obtain cumulative oil production 12% higher than the closest analogue.

The presented method, as well as the prototype method, were modeled in the CMG software package of the STARS module at the facility with the same geological and physical characteristics for different operating conditions. From the obtained calculations, the advantage of the method over the prototype was also revealed: a reduction in the percentage of water cut in the produced products from the reservoir, the exclusion of a breakthrough of the coolant in the producing well, cumulative oil production is higher than by the prototype by 10-15%.

The proposed method allows us to solve technical problems, such as working capacity in the reservoir with an inclined oil-water contact, reducing the percentage of water cut in the produced products from the reservoir. The breakthrough of the coolant in the production well is eliminated, which makes it possible to avoid a drop in the achieved pressure in the developed formation and thereby ensure a high flow of products into the production well. The transfer of the mouth of an inclined horizontal well to the injection of the working agent provides savings in the construction of an additional injection well. Cumulative oil production by the proposed method is higher than by the prototype by 10-15%.

Claims (1)

A method for developing a highly viscous oil deposit, including drilling vertical injection wells and horizontal inclined production wells, pumping a working agent through injection wells and taking oil through production wells, characterized in that they determine the level of water-oil contact — VOC, producing horizontal inclined from the mouth to the bottom a well is drilled with a location of at least 2–3 m above the level of the oil and gas complex; a vertical injection well is drilled with a bottom position above the bottom of the producing well by 5–8 m, the production well is perforated along the entire length of the inclined section, the vertical injection well is perforated in the formation zone in the direction of the production well mouth, stage by stage, as the working agent breaks out or product flooding above 95%, the production bottom of the horizontal inclined well is cut off above the breakthrough or flooding zone, and the opening area of the injection well is cut from the bottom by 1 / 3-1 / 2 of its entire length; when the entire developed zone is developed, the mouth of the producing inclined horizontal well is transferred to injection working agent.