CN118110569A - Low-permeability oil reservoir waste oil well group reservoir layer reconstruction geothermal energy development method - Google Patents

Abstract

The invention relates to a low-permeability oil reservoir waste oil well group reservoir stratum transformation geothermal energy development method and an operation method. The method mainly solves the problems that the existing low-permeability oil reservoir waste oil well group reservoir stratum modification geothermal energy development method is easy to cause large recharging pressure difference and small recharging flow. The method is characterized in that: determining a heat recovery well and at least one recharging well, laterally drilling a short-radius horizontal well from the recharging well to the heat recovery well along the geothermal energy development layer, fracturing along the direction of the short-radius horizontal well, recharging water into the recharging well, and simultaneously, recovering hot water from the heat recovery well. The development method adopts a combined development mode of sidetrack ultra-short radius horizontal well and fracturing, well groups are balanced in mining and filling, recharging pressure difference is small, recharging efficiency is high, and the aim of efficiently developing geothermal energy is achieved.

Description

A method for developing geothermal energy by transforming abandoned oil well groups in low permeability reservoirs

Technical Field

The invention relates to the field of geothermal energy development in oil fields, in particular to a method for developing geothermal energy through reservoir transformation of abandoned oil well groups in low-permeability oil reservoirs.

Background technique

Low permeability oil reservoirs generally use reservoir fracturing technology to extract oil. After a period of development, the injection and production efficiency of some well groups deteriorates, and continued development is not economically profitable, so they can only be abandoned, resulting in a waste of resources. In order to solve this waste, the reservoirs of inefficient abandoned oil well groups are reconstructed for geothermal energy development, while the original well groups are directly converted to geothermal development, which will result in very high injection pressure and high electricity consumption. The existing low permeability oil reservoir abandoned oil well group reservoir reconstruction geothermal energy development only uses secondary fracturing of the oil layer, resulting in a re-injection pressure difference of more than 5MPa, and a small re-injection flow rate of less than ^15m3 /h, resulting in poor development effect and low economic benefits.

Summary of the invention

In order to overcome the shortcomings of existing geothermal energy development methods for abandoned oil well group reservoir transformation in low permeability oil reservoirs, which easily cause large reinjection pressure difference and small reinjection flow rate, the present invention provides a geothermal energy development method for abandoned oil well group reservoir transformation in low permeability oil reservoirs. The development method adopts a combined development mode of side drilling ultra-short radius horizontal wells and fracturing, achieves balanced production and injection between well groups, small reinjection pressure difference, and high reinjection efficiency, thereby achieving the purpose of efficient development of geothermal energy.

The technical solution of the present invention is: a method for geothermal energy development by transforming the reservoir of abandoned oil well groups in low permeability oil reservoirs, determining a heat production well and at least one reinjection well, drilling a short-radius horizontal well from the reinjection well to the heat production well along the geothermal energy development layer, fracturing along the direction of the short-radius horizontal well, reinjecting water into the reinjection well, and simultaneously extracting hot water from the heat production well.

Furthermore, the distance H between the heat production well and the reinjection well is not less than 300m, the length L of the short radius horizontal well is not less than 200m, and the difference between H and L is 50m-100m.

Furthermore, the recharge water volume of a single recharge well is not less than 10m ³ /h.

Furthermore, there is one heat production well and two reinjection wells, which are located on both sides of the heat production well respectively.

Furthermore, there is one heat production well and one reinjection well.

Furthermore, the reinjection pressure difference between the reinjection water pressure and the produced water pressure is no more than 1 MPa.

The present invention has the following beneficial effects: Due to the adoption of the above scheme, the method adopts a development mode of combining a heat production well with one or more reinjection wells, re-establishes the connection between reservoir wells, and the balance of production and injection between well groups, which can revitalize abandoned assets, make full use of geothermal energy to obtain hot water for heating living areas or other oil production wells, save a lot of coal or natural gas, and achieve the dual effects of reducing development costs and energy conservation and emission reduction. It improves the thermal efficiency of geothermal development of abandoned oil well groups in low permeability oil reservoirs, and can be widely used in geothermal development of abandoned oil well groups in low permeability oil reservoirs, with considerable application prospects.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic plan view of a group of wells with one production well and two injection wells;

Fig. 2 is a longitudinal cross-sectional view of a one-production two-injection well group;

FIG3 is a schematic diagram of geothermal reservoir reconstruction of a one-oil production and two-injection well group;

Fig. 4 is a schematic plan view of a production and injection well group;

Fig. 5 is a longitudinal cross-sectional view of a production and injection well group;

FIG6 is a schematic diagram of geothermal reservoir reconstruction of a one-oil production and one-injection well group.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings:

First, determine whether the low-permeability reservoir inefficient abandoned oil well group meets the following technical conditions: (1) the reservoir permeability is less than 50 kilometres; (2) there are at least two wells in the low-permeability reservoir inefficient abandoned oil well group; (3) the distance between adjacent wells in the well group is not less than 300 meters. Only when the well group meets all the above conditions can this development method be implemented.

A method for developing geothermal energy by transforming a reservoir of an abandoned oil well group in a low permeability oil reservoir comprises the following steps:

Step 1. In the inefficient abandoned oil well group, determine one heat production well and at least one reinjection well, and the distance H between the heat production well and the reinjection well should be no less than 300m. A well group can have one heat production well and one reinjection well (hereinafter referred to as one production and one injection), or one heat production well and two reinjection wells (hereinafter referred to as one production and two injection). When the well group adopts the one production and two injection form, the heat production well is located between the two reinjection wells.

Step 2: Determine the inter-well connecting sand layers between the inefficient abandoned oil wells, and select a sand layer as the geothermal energy development layer. Reopen the window at the corresponding geothermal energy development layer on the reinjection well, and drill a short-radius horizontal well along the geothermal energy development layer to the heat production well. The length L of the short-radius horizontal well is not less than 200m, and the difference between H and L must be between 50m and 100m.

Step 3: Fracturing along the short-radius horizontal well to establish a fracture network communication channel with the heat production well.

Step 4: Recharge the well with cold water. The recharge water volume of a single well is required to be no less than ^10m3 /h. Start to produce hot water at the same time. According to actual application, the recharge pressure difference between the recharge water pressure and the produced water pressure is no more than 1MPa, and the water flow rate of the hot water well is no less than ^10m3 /h.

Example 1: Geothermal energy development using one extraction and two injections Before adopting this development method, the geothermal energy is extracted by secondary fracturing, the injection pressure difference is 7 MPa, and the injection volume of a single well is 10 m ³ /h.

According to this development method, as shown in Figure 1, HX1-2 well in the low-permeability reservoir inefficient abandoned oil well group is determined as a heat production well, HX1-1 well and HX1-3 well are determined as reinjection wells, the well spacing _H1 between HX1-1 well and HX1-2 well is 330m, and the well spacing _H2 between HX1-3 well and HX1-2 well is 370m. As shown in Figure 2, a sand layer is selected as a geothermal energy development layer. As shown in Figure 3, the two reinjection wells HX1-1 well and HX1-3 well are re-windowed, and short-radius horizontal wells are drilled along the geothermal energy development layer to the heat production well HX1-2 well. The length of the horizontal well _L1 is 250m and _L2 is 300m. Fracturing is carried out along the direction of the short-radius horizontal well to establish a fracture network communication channel with the heat production well. Cool water was reinjected into two reinjection wells HX1-1 and HX1-3 respectively, with a single well reinjection water volume of 20m ³ /h. While reinjecting cool water, hot water was produced from the heat production well HX1-2. The reinjection pressure difference was 0.9MPa, the water production flow rate of the heat production well was 40m ³ /h, the maximum liquid production temperature at the wellhead was 65℃, and the heat production power of the well group was 2.0 MW. The development effect was remarkable.

Embodiment 2: Geothermal energy development is carried out in the form of one extraction and one filling.

As shown in Figure 4, HX2-2 well in the low-permeability reservoir inefficient abandoned oil well group is determined as a heat production well, HX2-1 well is determined as a recharge well, and the well spacing H between HX2-1 well and HX2-2 well is 400m. As shown in Figure 5, a sand layer is selected as the geothermal energy development layer. As shown in Figure 6, the recharge well HX2-1 well is re-opened, and a short-radius horizontal well is drilled along the geothermal energy development layer to the heat production well HX2-2 well. The length of the horizontal well L is 300m. Fracturing is performed along the short-radius horizontal well direction to establish a fracture network communication channel with the heat production well. Cool water is recharged into the recharge well HX2-1 well, and the recharge water volume of a single well is ^10m3 /h. While recharging cool water, hot water is produced from the heat production well HX2-2 well. The recharge pressure difference is 1MPa, the water production flow rate of the heat production well is ^10m3 /h, the maximum liquid production temperature at the wellhead is 65℃, and the heat production power of the well group is 1MW.

Claims (6)

1. A low-permeability oil reservoir waste oil well group reservoir layer transformation geothermal energy development method is characterized in that: determining a heat recovery well and at least one recharging well, laterally drilling a short-radius horizontal well from the recharging well to the heat recovery well along the geothermal energy development layer, fracturing along the direction of the short-radius horizontal well, recharging water into the recharging well, and simultaneously, recovering hot water from the heat recovery well.

2. The method for developing geothermal energy for the reservoir reformation of the low-permeability oil reservoir waste oil well group according to claim 1, wherein the method comprises the following steps: the distance H between the heat recovery well and the recharging well is not less than 300m, the length L of the short-radius horizontal well is not less than 200m, and the difference between H and L is 50m-100m.

3. The method for developing geothermal energy for the reservoir reformation of the low-permeability oil reservoir waste oil well group according to claim 2, wherein the method comprises the following steps: and the single-well recharging water quantity of the recharging well is not less than 10m ³/h.

4. The method for developing geothermal energy for the reconstruction of a low permeability reservoir waste oil well group reservoir according to claim 3, wherein: the number of the heat recovery wells is one, the number of the recharging wells is two, and the recharging wells are respectively positioned at two sides of the heat recovery wells.

5. The method for developing geothermal energy for the reconstruction of a low permeability reservoir waste oil well group reservoir according to claim 3, wherein: the heat recovery well is one, and the recharging well is one.

6. The method for developing geothermal energy for the reconstruction of a low permeability reservoir waste oil well group reservoir according to claim 4 or 5, wherein: the recharging pressure difference between the recharging water pressure and the produced water pressure is not more than 1MPa.