RU2334096C1 - Method of massive type high-viscosity oil pool development - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: method involves drilling a well, injection of steam alternating with air via injection wells arranged above, withdrawal of oil via production wells arranged beneath, development of pool step and further stepwise development downside the pool in the same way till the pool is depleted. Horizontal wells are used as wells. During pool step development horizontal production wells are located parallel at the step bottom under horizontal injection wells. Development step interval comprises ca. 20-50 m. At the first step a heat carrier with maximum possible temperature of ca. 250-320°C is applied. When passing from one step to another, the heat carrier temperature is reduced by 30-60°C. At the lowest step the heat carrier temperature is sustained at 100°C level or over.

EFFECT: increased oil yield of a pool.

1 ex, 1 dwg

Description

The invention relates to the oil industry and may find application in the development of deposits of high-viscosity oil of massive type.

A known method of developing a reservoir of high-viscosity oil of massive type, including the drilling of priority pilot shafts for future production and injection wells with the opening of the reservoir. Water injection is carried out, pressure changes in the wellbore are recorded, water injection is stopped after a bottomhole pressure surge, indicating the massive structure of the reservoir within the considered development element. This element is drilled with vertical and / or horizontal producing and injection wells with an area system for their placement. Bottom faces or wellbores are distributed in such a way that producing wells open a productive formation near its roof, and injection wells - above or below the oil-water contact. Organize the displacement of oil in the vertical direction with the injection mode of the working agent, mainly water, from the condition that the current reservoir pressure in the development element is not lower than the initial reservoir pressure. At the same time, water thickened with polymer is pumped into injection wells in order to prevent premature breakthroughs of the working agent to production wells. According to the second option, the bottom holes or wellbores are distributed in such a way that at the first stage, the producing formation is opened in the middle of the producing wells, and at the second stage, horizontal lateral shafts are drilled near the top of the producing formation (RF patent No. 2297524, published 2007.04.20).

The known method is applicable for the development of oil deposits of relatively low viscosity and is not applicable for the development of deposits of high viscosity oil with a viscosity of more than 200 MPa · s.

Closest to the proposed invention in technical essence is a method of developing deposits of highly viscous oil, according to which wells are drilled, steam with air and air are pumped into them. They stop the wells for exposure and select products from them. First, wells are drilled in the vaulted part of the reservoir. They are exploited as injection-producing cyclically with steam injection with air, holding and selection of products until the bottom hole zone is drained. The upper well is transferred under gas injection. Below located in the reservoir operate as mining. At the same time, a number of wells are drilled below production wells and they are operated as injection-producing ones. Production wells after developing a zone of deposits between them and the injection well are transferred under gas injection. An injection well is stopped when design pressure is exceeded. Further development is carried out from top to bottom along the reservoir in a similar way until the development of a deposit (RF patent No. 2304707, published. 2007.08.20 - prototype).

The known method allows you to develop a reservoir of oil of almost any viscosity, however, the method requires a large flow of coolant (steam), has a duration and low oil recovery.

The proposed invention solves the problem of increasing oil recovery deposits.

The problem is solved in that in the method of developing a reservoir of high-viscosity oil of a massive type, including drilling wells, injecting steam in alternation with air through upstream injection wells, taking oil through downstream production wells, developing a reservoir stage and further developing in steps from top to bottom of the reservoir similarly, before producing a deposit, according to the invention, horizontal wells are used as wells, when developing a stage of a deposit, I place producing horizontal wells t in the bottom of the stage in parallel under the horizontal injection wells, when developing a deposit step by step, the interval of each stage is assigned about 20-50 m, the first stage uses a coolant with a maximum possible temperature of about 250-320 ° C, reduce the temperature of the coolant from stage to stage 30-60 ° C, while at the lower stage, the temperature of the coolant is not lower than 100 ° C.

The features of the invention are:

1. well drilling;

2. steam injection in alternation with air through higher located injection wells;

3. oil extraction through lower located production wells;

4. development of the level of deposits;

5. further development in steps from top to bottom of the deposit in a similar manner until the development of the deposit;

6. the use of horizontal wells as wells;

7. when developing the stage of the deposit, the placement of producing horizontal wells in the bottom of the stage in parallel under the injection horizontal wells;

8. when developing a deposit in steps from top to bottom, the appointment of the interval of each step is of the order of 20-50 m;

9. use at the first stage of the coolant with the maximum possible temperature of the order of 250-320 ° C;

10. a decrease from step to step of the temperature of the coolant by 30-60 ° C;

11. maintaining at the lower stage of the temperature of the coolant not lower than 100 ° C.

Signs 1-5 are common with the prototype, signs 6-11 are the essential distinguishing features of the invention.

SUMMARY OF THE INVENTION

When developing a reservoir of high-viscosity massive-type oil, the development is carried out in stages, passing as reserves are developed to the lower floors (steps). Existing development methods make it possible to select the main reserves from the reservoir, however, a significant part of the oil remains in the reservoir. This is due to the uncontrolled designation of the height of the stages of development and imperfect placement of wells. The technologies used are distinguished by an increased consumption of an expensive coolant. The proposed invention solves the problem of increasing oil recovery deposits. The problem is solved as follows.

Massive-type high-viscosity oil deposits are developed in steps from top to bottom. For each step, an interval with a height of 20-50 m is allocated in the thickness of the deposit. The first step is allocated under the roof of the deposit. Horizontal production and injection wells are drilled to the first stage. Production horizontal wells are placed at the bottom of the first stage. In parallel to producing horizontal wells above 2-10 m horizontal injection wells are drilled. At the first stage, a coolant with a maximum possible temperature of about 250-320 ° C is used. The coolant (steam) is pumped in alternation with air through injection wells and oil is taken through production wells. Development is carried out before the development of the zone of deposits in the first stage.

For the second stage, an interval of 20-50 m in height located under the first stage is distinguished in the thickness of the deposit. Horizontal production and injection wells are drilled to the second stage. In this case, vertical wellbores are used, previously drilled to the first stage. Production horizontal wells are placed at the bottom of the second stage. In parallel to producing horizontal wells above 2-6 m horizontal injection wells are drilled. In the second stage, a coolant with a temperature below the temperature of the coolant in the first stage is used at a temperature of 30-60 ° C. The coolant (steam) is pumped in alternation with air through injection wells and oil is taken through production wells. Development is carried out before the development of the zone of deposits in the second stage.

In a similar way, an oil reservoir is developed at the third stage, etc.

At the last lowermost stage, the coolant temperature is maintained not lower than 100 ° C.

The coolant injection at the first and subsequent stages contributes to the heating of the deposit not only of this stage, but also of the neighboring ones. The next stage appears to be warmed up due to the heat of the previous stage. It is possible to use a coolant with a lower temperature to warm up the next stage, as a result of which it becomes possible to lower the temperature of the coolant, starting from the second stage and then up to the last.

The drawing shows a layout of wells and development feet.

The injection well has a vertical wellbore 1 and horizontal wellbores 2 drilled at each development stage. The producing well has a vertical wellbore 3 and horizontal trunks 4 drilled at the bottom of each stage parallel to the horizontal trunks 2 of the injection well, h is the interval of the high-viscosity oil of massive type with a roof 5 and sole 6. h ₁ -h ₄ are the intervals of the development stages.

A reservoir of high-viscosity massive-type oil is developed in stages from top to bottom from the first stage with an interval of h ₁ to the last stage with an interval of h ₄ . The intervals h ₁ -h ₄ have a height of 20-50 m. The first step with an interval of h _{1 is} allocated under the roof 5 deposits. From the vertical wellbore 3, the horizontal wellbore 4 of the producing well is drilled into the bottom of the first stage. From the vertical wellbore 1 parallel to the horizontal wellbore 4 and above it, 2-10 m drill a horizontal wellbore 2 of the injection well. At the first stage, a coolant with a maximum possible temperature of about 250-320 ° C is used. The coolant (steam) is pumped in alternation with air through the injection well and oil is taken through the production well. Development is carried out before the development of the zone of deposits in the first stage.

For the second stage, an interval h ₂ with a height of 20-50 m located under the first stage is distinguished in the thickness of the deposit. Horizontal wells of production and injection wells are drilled to the second stage. In this case, use vertical shafts of 1 and 3 wells previously drilled to the first stage. The horizontal wellbore of the producing well is placed at the bottom of the second stage. Parallel to the horizontal well of the producing wells, a horizontal well of the injection well is drilled 2-10 m higher. In the second stage, a coolant with a temperature below the temperature of the coolant in the first stage is used at a temperature of 30-60 ° C. The coolant (steam) is pumped in alternation with air through injection wells and oil is taken through production wells. Development is carried out before the development of the zone of deposits in the second stage.

Similarly, develop an oil reservoir in the third, fourth and last fifth stage with intervals of h ₃ and h _4, respectively.

At the last lowermost stage, the coolant temperature is maintained not lower than 100 ° C.

Concrete example

A reservoir of high-viscosity massive oil is being developed. The top of the deposit is at a depth of 100 m, the sole is at a depth of 220 m. The temperature in the deposit is 8 ° C, pressure is 0.5 MPa, oil saturation is 0.70 ged units, porosity is 30%, permeability is 0.265 μm ² . The oil has a density of 956 kg / ^m3 and a viscosity of 7000 mPas. The deposit is developed by wells placed according to the drawing. The distance between the vertical shafts of the producing and injection wells is 100 m.

A reservoir of high-viscosity massive-type oil is developed in stages from top to bottom from the first stage with an interval of h ₁ to the last stage with an interval of h ₄ . The intervals h ₁ -h ₄ have a height of 30 m each. The first stage with an interval of h ₁ allocate 5 deposits under the roof. A horizontal well 4 of a producing well 98 m long is drilled from a vertical well 3 to the bottom of the first stage. A horizontal well 2 of an injection well 98 m long is drilled 6 meters parallel to the horizontal well 4 and above it, 6 meters long from a vertical well 1. A heat carrier with a temperature of 250 is used in the first well ° C. The coolant (steam) is pumped in alternation with air through the injection well and oil is taken through the production well. Development is carried out before the development of the zone of deposits in the first stage.

The second, third and fourth stages are developed similarly to the first. In the second stage, a coolant with a temperature of 200 ° C is pumped in, in the third stage with a temperature of 150 ° C, in the last lower stage with a temperature of 100 ° C.

As a result, it is possible to achieve oil recovery of a deposit of 50%, while known methods can achieve oil recovery of the order of 25-30%.

The application of the proposed method will improve the oil recovery of the reservoir while reducing the cost of heating the coolant.

Claims (1)

A method of developing a reservoir of high-viscosity oil of a massive type, including drilling wells, injecting steam in alternation with air through upstream injection wells, taking oil through downstream production wells, developing a reservoir level and further developing from the top down the reservoir in a similar manner to producing a reservoir, characterized in that horizontal wells are used as wells, when developing a deposit stage, the producing horizontal wells are placed at the bottom of the parallel stage Under the horizontal injection wells, during the development of the deposit step by step, the interval of each step is set to about 20-50 m, the coolant with the maximum possible temperature of about 250-320 ° C is used in the first step, and the coolant temperature is reduced from step to step by 30-60 ° C, while at the lower stage, the temperature of the coolant is not lower than 100 ° C.