CN106567700A - Retrofitting Method of Oilfield Reservoir - Google Patents

Abstract

The invention provides a method for reforming oilfield reservoirs. The transformation method includes: connecting the floating shoes, floating hoops, fracturing valves and multi-stage fracturing sliding sleeves to the casing from bottom to top to obtain a fracturing string device, and each stage of fracturing sliding sleeves includes a fixed Well fracturing sliding sleeves and multiple multi-cluster cementing fracturing sliding sleeves; place the fracturing string device between the oilfield reservoir and the wellhead and cement the well; open each fracturing sliding sleeve combination to fracturing the oilfield reservoir crack. The present invention is suitable for oil reservoirs with strong vertical heterogeneity, discontinuous distribution of oil layers, and multiple small layers that need to be fractured to build production. It can realize economical and effective transformation of multiple thin layers with similar physical properties in the vertical direction and relatively close distances. , improve the efficiency of cementing and fracturing sliding sleeve fracturing technology transformation, and reduce operating costs.

Description

Retrofitting Method of Oilfield Reservoir

technical field

The invention relates to the field of petroleum reservoir transformation, in particular to a method for transformation of oilfield reservoirs.

Background technique

With the rise of the concept of volume fracturing in recent years, casing cementing fracturing and sliding sleeve fracturing technology has gradually become a mainstream fracturing technology. There are three main forms of technical realization: (1) Schlumberger TAP The cementing and fracturing sliding sleeve infinite-stage fracturing technology represented by the valve, the pressure is transmitted between the stages through the hydraulic conduit, and the plugging tools are injected step by step from bottom to top to realize infinite-stage reservoir stimulation; (2) NCS The representative coiled tubing belt opening tool realizes the bottom-up step-by-step fracturing technology through mechanical positioning; (3) adopts the method of step-by-step throwing balls to open the fracturing valve from the bottom up to realize the step-by-step fracturing of a limited number of layers fracture. The above technologies are all applied in China, and are more suitable for staged fracturing of vertical wells and horizontal wells. However, for multi-thin-layer vertical wells with similar physical properties in the vertical direction and relatively close distances, layer-by-layer stimulation is required, and economical and effective stimulation operations cannot be realized. .

However, thin oil reservoirs in domestic oilfields often have strong heterogeneity in the vertical direction, the distribution of oil layers is discontinuous, and multiple small layers need to be fractured to build production. If the conventional casing cementing and fracturing sliding sleeve technology is adopted To achieve the purpose of producing each reservoir, a large number of repeated operations are required, which not only reduces the operation efficiency, but also causes waste of fracturing materials.

Contents of the invention

The main purpose of the present invention is to provide a method for reforming oilfield reservoirs, so as to realize unified reforming of multiple thin layers with similar physical properties and relatively close distances in the vertical direction.

In order to achieve the above purpose, the present invention provides a method for reforming oilfield reservoirs, the reforming method includes: connecting the combination of floating shoes, floating hoops, fracturing valves and multi-stage fracturing sliding sleeves to the casing from bottom to top The fracturing string device is obtained above, and each fracturing sleeve combination includes a cementing fracturing sleeve and multiple multi-cluster cementing fracturing sleeves; the fracturing string device is placed between the oilfield reservoir and the wellhead And cement the well; open each fracturing sleeve combination, and perform fracturing on the oilfield reservoir.

Further, the cementing and fracturing sliding sleeves in the fracturing sliding sleeve combinations of each stage are provided with a variable-diameter ball seat structure; the pistons of the multi-cluster cementing and fracturing sliding sleeves in each stage of the fracturing sliding sleeve combination are transmitted through pressure. The structure is connected; the multi-stage fracturing sleeve combination includes the first segment of the fracturing sleeve combination adjacent to the fracturing valve, and the upper segment of the fracturing sleeve combination located above the first segment, and the first segment The fracturing sleeve assembly is opened by means of wellbore pressure suppression or perforation, and the upper section of the fracturing sleeve assembly is opened by delivering an opening tool from the wellhead.

Furthermore, the opening method of the upper fracturing sliding sleeve assembly is as follows: after the opening tool reaches the position of the variable-diameter ball seat structure, the wellhead suppresses the pressure, and the variable-diameter ball seat structure goes down to the lower limit under the action of the downward difference, exposing the pressure transmission structure. The pressure hole and the pressure transmission hole communicate with the piston; when the pressure reaches the cracking pressure of the cementing and fracturing sliding sleeve, each multi-cluster cementing and fracturing sliding sleeve in the same level of fracturing sliding sleeve combination will open simultaneously.

Further, there is an anti-rotation structure between the opening tool and the reducing ball seat structure and between the reducing ball seat structure and the outer cylinder of the cementing and fracturing sliding sleeve.

Further, the diameters of the cementing and fracturing sliding sleeves in the fracturing sliding sleeve combinations at all stages are greater than or equal to the inner diameter of the casing after the variable diameter ball seat structure is drilled out.

Further, the reducing ball seat structure and the opening tool are made of soluble materials.

Further, there is a switch inside the cementing and fracturing sliding sleeve, and after the variable-diameter ball seat structure is drilled out, a switch tool is lowered to close the cementing and fracturing sliding sleeve.

Applying the technical scheme of the present invention, the present invention is applicable to oil reservoirs with strong vertical heterogeneity, discontinuous distribution of oil layers, and multiple small layers that need to be fractured to build production. Economically and effectively reform thin layers, improve the efficiency of cementing and fracturing sliding sleeve fracturing technology, and reduce operating costs.

Description of drawings

The accompanying drawings constituting a part of the present application are used to provide a further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:

Fig. 1 shows a schematic flow chart of a method for improving an oilfield reservoir according to an embodiment of the present invention; and

Fig. 2 shows a schematic cross-sectional structure diagram of a fracturing string device in the oil field reservoir stimulation method provided according to the embodiment of the present invention.

detailed description

It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and examples.

Thin oil reservoirs in domestic oilfields often have strong heterogeneity in the vertical direction, the distribution of oil layers is discontinuous, and multiple small layers need fracturing to build production. If conventional casing cementing and fracturing sliding sleeve technology is used to achieve production The purpose of each reservoir requires a large number of repeated operations, which not only reduces operating efficiency, but also causes waste of fracturing materials.

In order to solve the above problems, the present invention provides a method for reforming oilfield reservoirs. As shown in Fig. 1, the reconstruction method includes: connecting the floating shoe 6, the floating hoop 5, the fracturing valve 4 and the multi-stage fracturing sliding sleeve to the casing from bottom to top in order to obtain a fracturing string device (such as 2), each stage of fracturing sleeve assembly includes a cementing fracturing sleeve 2 and multiple multi-cluster cementing fracturing sleeves 1; the fracturing string device is placed between the oilfield reservoir and the wellhead And cement the well; open each fracturing sleeve combination, and perform fracturing on the oilfield reservoir.

The present invention is applicable to oil reservoirs with strong vertical heterogeneity, discontinuous distribution of oil layers, and multiple small layers that need to be fractured to build production. It can realize economical and effective transformation of multiple thin layers with similar physical properties in the vertical direction and relatively close distances. , improve the efficiency of cementing and fracturing sliding sleeve fracturing technology transformation, and reduce operating costs.

The cementing and fracturing sliding sleeve 2 in the fracturing sliding sleeve combination of each stage is provided with a variable-diameter ball seat structure; the pistons of each multi-cluster cementing and fracturing sliding sleeve 1 in each stage of the fracturing sliding sleeve combination pass through the pressure transmission structure connected; the multi-stage fracturing sleeve assembly includes the first section of the fracturing sleeve assembly adjacent to the fracturing valve 4, and the upper section of the fracturing sleeve assembly located above the first section of the fracturing sleeve assembly, and the first section The fracturing sleeve assembly is opened by means of wellbore pressure suppression or perforation, and the upper section of the fracturing sleeve assembly is opened by delivering the opening tool 3 from the wellhead.

Among them, the opening method of the upper fracturing sliding sleeve assembly is as follows: after the opening tool 3 reaches the position of the variable-diameter ball seat structure, the wellhead suppresses the pressure, and the variable-diameter ball seat structure goes down to the lower limit under the action of the downward difference, exposing the pressure transmission structure. The pressure hole and the pressure transmission hole communicate with the piston; when the pressure reaches the opening pressure of the cementing and fracturing sliding sleeve 2, each multi-cluster cementing and fracturing sliding sleeve 1 in the same level of fracturing sliding sleeve combination is simultaneously opened.

Preferably, anti-rotation structures are provided between the opening tool 3 and the reducing ball seat structure and between the reducing ball seat structure and the outer cylinder of the cementing and fracturing sliding sleeve 2 . The diameters of the cementing and fracturing sliding sleeves 2 in the fracturing sliding sleeve combinations at all levels are greater than or equal to the inner diameter of the casing after drilling out of the variable-diameter ball seat structure. The reducing ball seat structure and the opening tool 3 are made of soluble materials. There is a switch inside the cementing and fracturing sliding sleeve 2, and after the variable-diameter ball seat structure is drilled out, a switch tool is lowered to close the cementing and fracturing sliding sleeve 2.

The method for improving the oilfield reservoir provided by the present invention will be specifically described below.

Connect the floating shoe 6, floating hoop 5, fracturing valve 4 and multi-stage fracturing sliding sleeve to the casing from bottom to top in order to obtain a fracturing string device, and run it into the well together with the casing to adjust the depth The length of the pipe string is such that each cementing and fracturing sliding sleeve 2 corresponds to the interval to be stimulated. For layers that require multi-cluster stimulation, a multi-cluster cementing and fracturing sliding sleeve 1 is lowered into each layer that needs to be stimulated, and the multi-cluster cementing and fracturing sliding sleeves 1 are connected by one or more structures that can transmit pressure. The ball seats of the cementing and fracturing sliding sleeves 2 in each section increase in size from bottom to top, and the multi-cluster cementing and fracturing sliding sleeves 1 are in the lowermost section of the sliding sleeve. Cementing, waiting for coagulation.

When reconstruction is required, the first section adopts wellbore pressure suppression or perforation to open the fracturing channel of the first section. The opening of the second section and the above section is opened by throwing a ball. When the multi-cluster cementing fracturing sleeve 1 is working, the opening tool 3 is put into the wellhead, pumped with a small displacement, the opening tool 3 reaches the ball seat position, the wellhead suppresses pressure, and the ball seat moves down to the lower limit under the action of the pressure difference, exposing The pressure transmission hole communicates with the piston. Each multi-cluster sliding sleeve piston of the same level is connected through a pressure transmission structure, and has no pressure transmission structure with the casing. Continue to increase the pressure in the casing. When the cracking pressure of the cementing and fracturing sliding sleeve 2 is reached, the multi-cluster cementing and fracturing sliding sleeves 1 of the same level are simultaneously opened, and fracturing can be performed sequentially from bottom to top according to the main program.

Before pumping is required, the drilling and grinding system is drilled down and the ball seat is drilled sequentially from bottom to top to restore the diameter of the casing. Each cementing and fracturing sliding sleeve 2 has a switchable function, and if it needs to be closed later, a switch tool is lowered to close the fracturing sliding sleeve.

Each cementing and fracturing sliding sleeve 2 has a switchable function. If it needs to be closed in the later stage, the switching tool is lowered to realize closing the fracturing sliding sleeve through hydraulic pressure or by lifting and releasing the pipe string.

From the above description, it can be seen that the above-mentioned embodiments of the present invention have achieved the following technical effects: the present invention is applicable to those with strong vertical heterogeneity, discontinuous distribution of oil layers, and the development of multiple small layers that require fracturing to build production. Reservoirs can achieve economical and effective transformation of multi-thin layers with similar physical properties in the vertical direction and close distances, improve the efficiency of cementing and fracturing sliding sleeve fracturing technology transformation, and reduce operating costs.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (7)

1. a method for reforming oilfield reservoirs, characterized in that, the method for reforming comprises: The combination of floating shoes (6), floating hoops (5), fracturing valves (4) and multi-stage fracturing sliding sleeves are sequentially connected to the casing from bottom to top to obtain a fracturing string device, and each stage of fracturing The sliding sleeve combination includes a cementing and fracturing sliding sleeve (2) and a plurality of multi-cluster cementing and fracturing sliding sleeves (1); placing the fracturing string device between the oilfield reservoir and the wellhead and cementing the well; Each of the fracturing sliding sleeve assemblies is opened to perform fracturing on the oilfield reservoir. 2. The transformation method according to claim 1, characterized in that, the cementing and fracturing sliding sleeves (2) in the fracturing sliding sleeve combinations at each stage are provided with a variable-diameter ball seat structure; The pistons of each of the multi-cluster cementing and fracturing sliding sleeves (1) in the fracturing sliding sleeve combination are connected through a pressure transmission structure; the multi-stage fracturing sliding sleeve combination includes The adjacent first-stage fracturing sleeve assembly, and the upper-stage fracturing sleeve assembly located above the first-stage fracturing sleeve assembly, and the first-stage fracturing sleeve assembly adopts wellbore pressure suppression or perforation The above-mentioned fracturing sliding sleeve combination is opened by means of delivering an opening tool (3) from the wellhead. 3. The transformation method according to claim 2, characterized in that, the opening method of the upper fracturing sliding sleeve assembly is: after the opening tool (3) reaches the position of the variable-diameter ball seat structure, the wellhead is pressed pressure, the variable diameter ball seat structure goes down to the lower limit under the action of the downward difference, exposing the pressure transmission hole of the pressure transmission structure, and the pressure transmission hole communicates with the piston; when the pressure reaches the cementing and fracturing sliding sleeve ( 2) when the cracking pressure is lower than 2), each of the multi-cluster cementing and fracturing sliding sleeves (1) in the same level of the fracturing sliding sleeve combination is simultaneously opened. 4. The reconstruction method according to claim 3, characterized in that, between the opening tool (3) and the reducing ball seat structure and between the reducing diameter ball seat structure and the cementing and fracturing sliding sleeve (2) There is an anti-rotation structure between the outer cylinders. 5. The transformation method according to claim 3, characterized in that, the diameter of the cementing and fracturing sliding sleeves (2) in the fracturing sliding sleeve combinations at each stage after the drilling of the variable-diameter ball seat structure is are greater than or equal to the inner diameter of the casing. 6. The modification method according to claim 3, characterized in that, the reducing ball seat structure and the opening tool (3) are made of soluble materials. 7. The reconstruction method according to claim 3, characterized in that, the inside of the cementing and fracturing sleeve (2) has a switch, and after the variable-diameter ball seat structure is drilled out, the switch tool will be lowered into the The cementing and fracturing sliding sleeve (2) is closed.