CN103628848B - Multidirectional interlayer displacement in flooding oil production method and system - Google Patents

Abstract

The invention relates to a method and system for multi-directional interlayer water injection displacement oil recovery. The system includes a water injection well and a cluster well group, and the cluster well group is composed of 2 to 20 oil production wells. According to the distribution law of the reservoir, set 1 to 10 layers of water injection circles. Water injection wells are arranged on each water injection circle, and cluster well groups are arranged in the center of the water injection circle or between two water injection circles. The number of water injection wells on each water injection circle, the center of the water injection circle and/or the number of cluster well groups between two water injection circles are determined according to the size of the reservoir distribution in the production area. According to the oil exploration technology, grasp the reservoir trap structure, oil layer distribution and oil layer thickness, inject water into the oil layer in multiple directions through the water injection well, drive oil to the cluster well group, and use the cluster well group to extract oil from the oil layer. The oil flooding is oil flooding at the same layer, the water injection volume of the oil layer is 10-30 times of the oil production volume, and the temperature of the water injection is raised to 60-70°C by the ground source heat pump. The invention drives oil from a plurality of water injection points to one oil production point, thereby improving the recovery rate of crude oil.

Description

Multi-directional interlayer water flooding oil recovery method and system

technical field

The invention belongs to the technical field of petroleum exploitation, and relates to a method and system for multi-directional interlayer water flooding and displacement oil recovery.

Background technique

In the initial stage of crude oil exploitation, crude oil is exploited only by natural energy, commonly known as primary oil recovery, and its recovery rate generally does not exceed 15%. After a certain period of crude oil extraction, due to the lack of energy space in the formation, it is necessary to use water injection or gas injection to make up for the insufficient volume produced. The method of supplementing formation energy to exploit oil fields is called secondary oil recovery, and its recovery rate generally does not exceed 50%. The oil recovery method by injecting working agent into the formation or introducing other energy is called tertiary oil recovery, also known as EOR method. However, after the water injection mining process and the EOR mining method, the current world advanced level is 65% to 70%. Therefore, the existing extraction technology causes a large amount of petroleum resources to stay underground. According to statistics, every 1% increase in the recovery rate will increase the national oil production by 150 million tons.

The Chinese invention patent with the notification number CN 101956544 B discloses a method for oil production in multi-bottom and multi-branch wells using self-flowing water injection. The patent is: "drilling the first well and the second well; Drill the water injection branch, the water injection branch passes through the water layer and the oil layer under the water layer; after the water injection branch is drilled, it goes down into the slotted pipe to communicate the water layer and the oil layer; due to the high pressure of the water layer and the low pressure of the oil layer, the water in the water layer automatically flows into the oil layer , to replenish energy for the oil layer; after the water injection branch slotted pipe is lowered, cement plugs are used to block the junction of the branch and the first wellbore; the second well is used to recover oil from the oil layer; the first well is drilled using conventional drilling techniques. The first oil production branch and the second oil production branch realize the oil production function of the first well". This patent realizes two functions of oil production and water injection in one well, which saves the well groove and provides convenience for subsequent production stimulation measures, but cannot greatly increase the recovery rate.

Contents of the invention

In order to overcome the deficiency of the low recovery rate of the existing oil recovery technology, the present invention provides a multi-directional interlayer water flooding displacement oil recovery method to improve the recovery rate of oil recovery production. Another object of the present invention is to provide a multi-directional interlayer water flooding oil recovery system for realizing the above method.

The multi-directional interlayer water flooding oil recovery method of the present invention grasps the oil reservoir trap structure, oil layer distribution and oil layer thickness according to the petroleum exploration technology, arranges water injection wells and cluster well groups in the oil reservoir circle, and flows through the water injection wells in multiple directions. Inject water into the oil layer, drive oil to the cluster well group, and use the cluster well group to extract oil from the oil layer. The oil displacement is oil displacement in the same layer, the water injection volume between the oil layers is 10-30 times (weight ratio) of the oil production volume, and the water injection temperature is 60-70°C.

The multi-directional interlayer water injection displacement oil production system of the present invention comprises water injection wells and cluster well groups, and the cluster well groups are composed of 2 to 20 oil production wells. According to the distribution law of the reservoir, set 1 to 10 layers of water injection circles. Water injection wells are arranged on each water injection circle, and cluster well groups are arranged in the center of the water injection circle and/or between two water injection circles; the number of water injection wells on each water injection circle, the center of the water injection circle and/or two water injection circles The number of cluster well groups between circles is determined according to the size of the oil reservoir distribution in the production area.

Oil production wells include multi-branch wells and oil production horizontal wells. Oil production horizontal wells include oil production vertical well sections and oil production horizontal sections. Multi-branch wells include vertical sections and 2 to 6 branch sections. The branch section of the multilateral well is directional inclined straight structure or horizontal structure. The branch sections are located within the thickness range of the same oil layer or between different oil layers. The branch section of the multi-branch well is filled with gravel, on the one hand to prevent the horizontal well from collapsing due to geological reasons, and on the other hand to ensure a good oil seepage space for oil flow. The length of the oil production horizontal section is 0.5 to 0.8 times the distance between two water injection circles, and the oil production horizontal wells in each cluster well group are arranged in one oil layer or in different oil layers. The oil production horizontal section is located in the same oil layer or multiple oil layers, and each oil layer has an oil production port.

The water injection well is a horizontal water injection well. The horizontal water injection well includes a water injection vertical well section and a water injection horizontal section. The water injection horizontal section is provided with water injection points. The number of water injection points is determined according to the length of the water injection horizontal section. Horizontal water injection wells are arranged in a single small oil layer or between 2 to 5 small oil layers at the edge of the reservoir. The total length of horizontal water injection wells in each small oil layer is 1 to 5 times the circumference of the oil-water interface.

The multi-directional interlayer water flooding oil recovery method of the present invention is an oil recovery method for improving underground crude oil recovery obtained on the basis of dynamic model simulation experiments. . By simulating multi-directional interlayer water flooding for oil recovery, 10 to 30 times the amount of water will be used for displacement, and the recovery rate will be increased to more than 85%. Water pressure flooding and gravity flooding are adopted on the basis of reservoir description and grasp of reservoir trap structure, oil layer distribution and oil layer thickness. Hydraulic flooding is multi-directional interlayer water injection, from multiple points to one point in the same layer to drive oil. Gravity flooding is to use the height difference between layers to drive oil by means of the buoyancy of oil, that is, to arrange horizontal water injection wells around the entire oil reservoir in a single small layer or between multiple small layers of the reservoir, and the horizontal water injection wells are located in each small layer. The total length between the layers is 1 to 3 times longer than the perimeter of the oil-water interface. Depending on the size of the traps in the entire reservoir and according to the well layout of the oil wells in the reservoir, 1 to 10 layers of water injection circles are set up, and oil production wells are arranged in the middle of the water injection circles and between the two layers of water injection circles. When cluster wells are selected for oil production wells, according to the geological requirements of cluster well group layout, the depth directions of branch sections are staggered from each other, and the star-shaped arrangement is adopted to conveniently control the area of oil production area.

Compared with the prior art, the beneficial effect of the present invention is that oil is driven from multiple water injection points to one oil production point, oil is driven in the same oil layer, the number of water injection points is determined according to the level of permeability, and water injection is carried out in layers. The difference in permeability determines different water injection pressures, controls the water injection layer according to the production demand, and improves the recovery of crude oil.

Description of drawings

Fig. 1 is the central oil recovery schematic diagram of multi-directional interlayer water injection of the present invention to displace single-layer water injection circle;

Fig. 2 is the schematic diagram of another embodiment of the present invention;

Fig. 3 is the schematic diagram of another embodiment of the present invention;

Fig. 4 is the schematic diagram of cluster well group structure;

Figure 5 is a schematic diagram of the layout of oil production horizontal wells.

in:

1—Water injection well, 2—Cluster well group, 3—Oil production well, 4—First water injection circle, 5—Second water injection circle, 6—Third water injection circle, 7—Oil production vertical well section, 8—Oil production Horizontal section, 9-gravel, 10-oil layer, 11-vertical section, 12-branch section, 13-production horizontal well, 14-multi-branch well, 15-fourth water injection circle, 16-water injection circle, 17-water injection vertical well Section, 18—horizontal section of water injection, and 19—fifth layer of water injection circle.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

Example 1

As shown in Figure 1, the multi-directional interlayer water injection displacement oil recovery system of the present invention is a small oil reservoir well area, and a layer of water injection circle 16 is arranged on the edge of the reservoir, and 8 water injection wells are arranged on the water injection circle, and 1 group of clusters The well group 2 is arranged in the center of the water injection circle, and the cluster well group is composed of production wells 3 . As shown in Figure 4, the oil production well includes 1 multi-branch well 14 and 6 oil production horizontal wells 13, the oil production horizontal well includes the oil production vertical well section 7 and the oil production horizontal section 8, and the multi-branch well is divided into a vertical section 11 and 4 branch sections 12. The branch section 12 of the multi-branch well is a directional inclined straight structure, and the branch section is located between different oil layers. The lateral sections 12 of the multilateral well 14 are filled with gravel 9 . The oil production horizontal wells in each cluster well group are arranged in different oil layers, and the oil production horizontal section 8 of each oil production horizontal well is located in the same oil layer 10 . As shown in Figure 5, the water injection well 1 is a horizontal water injection well. The horizontal water injection well includes a water injection vertical section 17 and a water injection horizontal section 18. The water injection horizontal section is provided with water injection points. The number of water injection points is determined according to the length of the water injection horizontal section. Horizontal water injection wells are arranged in a single small oil layer or between two small oil layers at the edge of the reservoir. The total length of horizontal water injection wells in each small oil layer is twice the perimeter of the oil-water interface.

The process of multi-directional interlayer water flooding and oil recovery in the present invention is as follows: grasp the reservoir trap structure, oil layer distribution and oil layer thickness according to the petroleum exploration technology, inject water into the oil layer in multiple directions through the water injection well, and drive oil to the cluster well group, The oil in the oil layer is extracted by using the cluster well group, and the oil is driven in the same oil layer. The amount of water injected between oil layers is 20 times the oil production (weight ratio), and the temperature of water injection is 65°C.

Example 2

Another embodiment of the present invention is shown in FIG. 2 , which is a small and medium oil reservoir, using three layers of water injection rings 16 . A first layer of water injection circle 4 is arranged in the middle of the oil reservoir, and eight water injection wells 1 are arranged on the first layer of water injection circle. A third water injection circle 6 is arranged on the edge of the reservoir, and there are 6 water injection wells on the third water injection circle. A second water injection circle 5 is arranged between the first water injection circle and the third water injection circle, and 6 water injection wells are arranged on the second water injection circle. There is a group of cluster wells 2 in the center of the first water injection circle, and there are 3 cluster well groups between the first water injection circle and the second water injection circle. There are 5 cluster well groups 2 among them. The length of the oil production horizontal section 8 is 0.6 times the distance between two water injection circles. The oil recovery process of multi-directional interlayer water flooding is the same as that in Embodiment 1.

Example 3

Yet another embodiment of the present invention is shown in FIG. 3 , which is an oil production area of a large and medium-sized oil reservoir, and adopts five layers of water injection rings 16 . A first layer of water injection circle 4 is arranged in the middle of the oil reservoir, and three water injection wells 1 are arranged on the first layer of water injection circle. 6 water injection wells are arranged in the second water injection circle 5, 8 water injection wells are arranged on the third water injection circle 6, 12 water injection wells are arranged in the fourth water injection circle 15, and 12 water injection wells are arranged in the fifth water injection circle 19 . There is one cluster well group 2 in the center of the first water injection circle, four cluster well groups are set between the first water injection circle and the second water injection circle, and the second water injection circle and the third water injection circle There are 6 cluster well groups 2 between them, 8 cluster well groups 2 between the third and fourth water injection circles, and 8 cluster well groups 2 between the fourth and fifth water injection circles. 12 cluster well groups 2.

Claims (5)

1. the system that a Multidirectional interlayer displacement in flooding recovers the oil, including water injection well (1) and collecting well group (2), described collecting well group (2) is made up of 2～20 mouthfuls of producing wells (3), it is characterized in that: according to the regularity of distribution of oil reservoir, arrange 1～10 layer of water filling circle (16)；Described water injection well (1) is arranged on every layer of water filling circle, and described collecting well group (2) is arranged between center and/or two water filling circles of water filling circle；On every layer of water filling circle, between the quantity of water injection well, the center of water filling circle and/or two water filling circles, the quantity of collecting well group determines according to the size of oil-producing region oil pool distribution；Described horizontal flood well is arranged between single little oil reservoir (10) or 2～5 little oil reservoirs of oil pool outline, total length is oil-water interfaces girth 1～3 times of every horizontal water injection well of little oil reservoir；Described producing well includes multilateral well (14) and oil recovery horizontal well (13), and described oil recovery horizontal well includes oil recovery straight well section (7) and oil recovery horizontal segment (8), and described multilateral well divides and includes vertical section (11) and 2～6 son fields (12)；The geologic requirements arranged according to collecting well group, the depth direction of son field is staggered mutually, uses starlike layout.

The system that Multidirectional interlayer displacement in flooding the most according to claim 1 recovers the oil, it is characterized in that: the son field (12) of described multilateral well (14) is orientation tiltedly straight structure or horizontal structure, described son field is in the range of same core intersection or between different oil reservoir.

The system that Multidirectional interlayer displacement in flooding the most according to claim 1 recovers the oil, is characterized in that: the son field (12) of described multilateral well (14) fills gravel (9).

The system that Multidirectional interlayer displacement in flooding the most according to claim 1 recovers the oil, it is characterized in that: 0.5～0.8 times of the spacing of described a length of two the water filling circles of oil recovery horizontal segment (8), the oil recovery horizontal well in each collecting well group (2) is arranged in an oil reservoir or is arranged in different oil reservoirs；Oil recovery horizontal segment (8) is positioned at same oil reservoir (10) or multiple oil reservoir, and each oil reservoir is provided with production ports.

The system that Multidirectional interlayer displacement in flooding the most according to claim 1 recovers the oil, it is characterized in that: described water injection well (1) is horizontal flood well, described horizontal flood well includes water filling straight well section (17) and water filling horizontal segment (18), described water filling horizontal segment is provided with injection point, and the quantity of injection point determines according to the length of water filling horizontal segment.