CN106050208A - Dual horizontal well for improving reservoir space physical property and enhancing gas production efficiency and construction method - Google Patents

Abstract

The present invention relates to a double horizontal well and method for improving physical properties of reservoir space and increasing gas production efficiency. The double horizontal well for improving physical properties of reservoir space and improving gas production efficiency includes a vertical well, an upper horizontal well and a lower horizontal well. The upper horizontal well and the lower horizontal well are parallel to each other and extend along the same direction, both of which communicate with the vertical well, and the lower horizontal well is connected to the bottom end side of the vertical well. Because the present invention adopts the well layer of the above structure, the first horizontal well is first drilled in the upper horizontal well and the lower horizontal well, and when the second horizontal well is drilled, the first horizontal well has been affected, making its permeability With certain improvements, this has expanded from the previous planar transformation to space transformation, which can achieve the purpose of increasing gas production and resource utilization.

Description

Dual-horizontal wells and structural methods for improving physical properties of reservoir space and increasing gas production efficiency

technical field

The invention relates to a double-horizontal well and a method for improving physical properties of reservoir space and increasing gas production efficiency, and belongs to the technical field of energy exploitation.

Background technique

In recent years, my country's energy is facing two serious problems. First, there is a large gap between oil and gas supply and demand, and a large amount of oil and natural gas needs to be imported from overseas every year. In 2012, 271 million tons of crude oil and 42.5 billion cubic meters of natural gas were imported, and their dependence on imports reached 58% and 28% respectively. Oil, in particular, has greatly exceeded the psychological defense line of 50%, seriously affecting the national energy strategic security; Reasonably, in my country's energy composition, coal accounts for as high as 80%, which not only pollutes the atmospheric environment, but also endangers people's health.

At present, the accumulation mechanism of unconventional energy is quite different from that of conventional energy, which is largely reflected in the difficulty of mining. As mentioned above, my country's unconventional energy resources have great resource potential. The shale gas resources are estimated to be more than 130 trillion cubic meters, and the coalbed methane resources are more than 37 trillion cubic meters, both of which are world leaders. However, it is still technically difficult to extract it, especially compared with the United States, which has done a better job in this area. my country's geological conditions are also unique, as shown in: In terms of shale gas, the United States is mainly The shale deposited in these two environments is not only poor in homogeneity, but also has a large change in lateral thickness. Even for marine strata, such as the Sichuan Basin, due to the strong tectonic activities in the later stage, the transformation effect is obvious. In terms of coalbed methane, the United States is dominated by medium-rank coals, that is, coals in the middle evolution stage. In this case, they have both high gas content and certain permeability. However, the areas where coalbed methane is currently exploited in my country are high-rank coal areas. Although the gas content is high, the permeability is poor, and the coal is usually not the primary structure coal, and the fracturing effect is not very good.

my country has such a large amount of unconventional energy resources, and to exploit it, we must have corresponding drilling, fracturing, and drainage technologies, otherwise, the amount of resources will always be just the amount of resources, and cannot be turned into production, or commercial mining. In order to achieve large-scale commercial mining, it is necessary to address the geological conditions for the formation of unconventional energy in my country—mainly including thickness, diagenesis, burial depth, transformation conditions, and gas-bearing properties. Carry out corresponding technological measures. At present, although this has been done, the effect is not ideal, such as drilling vertical wells for fracturing, drilling horizontal wells for staged fracturing, and pinnate wells, etc., all of which are true for the transformation of the reservoir (coal seam, shale layer) on the plane , is nothing more than the size of the area. This is possible for thin coal seams and shale layers (thickness less than two meters), but for thicker layers, it cannot be involved in the vertical direction. Therefore, how to transform the coal seam and shale layer three-dimensionally is the key to improving the gas production rate.

As a kind of unconventional energy, coalbed methane and shale gas are mainly characterized by the community of generation and storage, that is, the place where the gas is generated and the place where the gas is stored is one place. For conventional oil and gas, the place where oil and gas are generated is not the same place as the place where oil and gas are stored. The places where gas is generated are usually mudstone, shale, and coal seams, which are mainly composed of very fine-grained substances and a large amount of organic matter, so the porosity and permeability are very poor, or there is almost no permeability. So, how to exploit the gas stored in it?

At present, in the process of mining coalbed methane and shale gas at home and abroad, great efforts have been made in drilling and fracturing. For example, in addition to the usual vertical well casing drilling, there are also vertical wells without casing, vertical well digging wells, directional inclined wells, horizontal wells, horizontal pinnate wells, and vertical wells and horizontal wells docking—that is, U-shaped wells. Then, depending on the situation, they are fracked.

It can be seen from the above that all drilling types, including fracturing, improve the physical properties of the target layer from the surface, and the difference is nothing more than the different radius, range, and direction of stimulation. Fractures are only extensions of some ranges of reservoir physical properties on the plane of the target layer.

Straight downhole casing. Drilling can only affect a very small range around the well, and through fracturing, the physical properties of a certain layer can only be expanded accordingly, and the range along the principal stress is slightly larger and the range of the secondary stress is smaller.

Naoi pottery hole. It is only limited around the wellbore. Although it has the function of space transformation, the scope is too small. horizontal well. As the name suggests, it is a well extending along the layer, and it only plays a transformation role along a certain direction on the surface, and it is still on the plane.

In the above, not only the drilling is limited to a small area around the wellbore, but even if it is far away from the wellbore, the plane is only modified along a certain direction. Especially for fracturing, because there is no place for pressure relief, the fracturing effect is usually not good.

Contents of the invention

The technical problem to be solved by the present invention is to provide a dual-horizontal well and its method for improving the physical properties of the reservoir space and increasing the gas production efficiency, so as to overcome the problems in the prior art that drilling is only limited to a small area around the wellbore, or even if it is far away from the wellbore, it is only Transform the plane along a certain direction. Especially for fracturing, because there is no place for pressure relief, the fracturing effect is usually not good.

The technical solution of the present invention to solve the above technical problems is as follows: a double horizontal well that improves the physical properties of the reservoir space and improves the gas production efficiency, including a vertical well, an upper horizontal well and a lower horizontal well, the upper horizontal well and the lower horizontal well are parallel to each other and along the Extending in the same direction, they all communicate with the vertical wells, and the lower horizontal wells are connected to the bottom side of the vertical wells.

The beneficial effects of the present invention are: due to the adoption of the above-mentioned well formation, the first horizontal well is first drilled in the upper horizontal well and the lower horizontal well, and the first horizontal well has already been affected when the second horizontal well is drilled. , That is to say, the upper horizontal well is drilled first, and then the upper horizontal well has been affected when the lower horizontal well is drilled, or the lower horizontal well is drilled first, and the lower horizontal well has been affected when the upper horizontal well is drilled, so that the permeability has been improved to a certain extent. It has expanded from the plane renovation in the past to the space renovation, which can achieve the purpose of increasing gas production and resource utilization.

On the basis of the above technical solutions, the present invention can also be improved as follows.

The present invention is a double horizontal well that improves the physical properties of the reservoir space and improves the gas recovery efficiency as described above. Further, the distance between the upper horizontal well and the lower horizontal well is 30-40 meters.

The present invention is a dual-horizontal well that improves the physical properties of the reservoir space and improves the gas recovery efficiency as described above. Further, the length of the upper horizontal well and the lower horizontal well is 600 to 800 meters.

The present invention also provides a method for improving the physical properties of the reservoir space and improving the gas production efficiency by using the above-mentioned double horizontal well, which is characterized in that it comprises the following steps: Step 1) determining the land blocks rich in coalbed methane and shale gas;

Step 2), first drill a vertical well, drill to the bottom of the coalbed methane and shale gas layers, and then start to build up at the bottom of the vertical well. Using combined dynamic drilling tools, the dogleg angle of the build-up section is designed to be 4.5°/30m, and the section design It is a single circular arc profile, and the horizontal well is drilled;

Step 3), drilling the upper horizontal well 30-40 meters above the lower horizontal well.

According to the method for improving reservoir space properties and gas production efficiency with double horizontal wells as described above in the present invention, further, the upper horizontal wells are more than two horizontal wells arranged in parallel and extending in one direction.

The present invention also provides another method for improving the physical properties of the reservoir space and improving the gas production efficiency by using the above-mentioned double horizontal well, which includes the following steps: Step 1) determining the land blocks rich in coalbed methane and shale gas;

Step 2), first drill a vertical well, drill to the bottom of the coalbed methane and shale gas layers, and then start to build up at a distance of 30-40 meters from the bottom of the vertical well. Using combined dynamic drilling tools, the dogleg angle of the build-up section is designed to be 4.5° /30m, the profile is designed as a single arc profile, and the horizontal well is drilled;

Step 3), build up at 30-40 meters from the bottom of the vertical well, use combined dynamic drilling tools, design the dogleg angle of the buildup section to be 4.5°/30m, and design the profile as a single arc profile, and drill the horizontal well.

The method for improving reservoir space properties and increasing gas production efficiency with double horizontal wells of the present invention is characterized in that the upper horizontal wells are more than two horizontal wells arranged in parallel and extending in one direction.

As mentioned above, the present invention utilizes the double horizontal wells to improve the physical properties of the reservoir space and the gas production efficiency method, further, the upper horizontal well and the lower horizontal well are fractured.

As mentioned above, the present invention uses double horizontal wells to improve the physical properties of the reservoir space and improve the gas production efficiency. Further, firstly, the lower horizontal well section is fractured, and then the lower horizontal well is fractured; the horizontal wells of the upper horizontal well and the lower horizontal well are The length of the section is 600-800 meters, and the interval between the fracturing sections is set at 60-80 meters. The fracturing starts from the farthest end of the horizontal section from the vertical well to the place close to the vertical well.

Since the length of the horizontal section is 600-800 meters, the interval between the fracturing sections is set at 60-80 meters, which means that the lower horizontal section is divided into ten sections for fracturing, and the fracturing is from the farthest end of the horizontal section to the vertical well section. start in sequence.

Assume that the horizontal section is 800 meters, and the interval between fracturing sections is 80 meters. Then the fracturing well section is 800-720 meters, 720-640 meters, 640-560 meters, 560-480 meters, 480-400 meters, 400-320 meters, 320-240 meters, 240- 160-meter section, 160-80-meter section, and 80-0-meter section.

First of all, perforate it (enter the perforator, shoot the casing, cement sheath, until the coal or shale layer, open the channel for the gas to flow into the wellbore, called perforation), the perforator used for perforation is The bullet-type perforator uses 102 guns and 127 bullets, and a 60-degree phase angle is used for perforating, with 16 holes/m. Next, start fracturing, with displacement of 2.2-2.4m ³ /min, fluid volume in each section ranging from 800-1200m ³ , proppant dose of 100-200t in each section, mainly 40/70 mesh proppant, average sand ratio 3%-5%.

Then, the upper horizontal well is also fractured.

The method of the invention not only improves the reservoir layer in plane, but also improves the reservoir layer in space.

Description of drawings

Fig. 1 is a schematic diagram of the structure of a double horizontal well that improves the physical properties of the reservoir space and improves the gas production efficiency according to the present invention.

In the accompanying drawings, the list of parts represented by each label is as follows:

1. Vertical well, 2. Upper horizontal well, 3. Lower horizontal well.

detailed description

The principles and features of the present invention are described below in conjunction with the accompanying drawings, and the examples given are only used to explain the present invention, and are not intended to limit the scope of the present invention.

As shown in Figure 1, a double horizontal well that improves the physical properties of the reservoir space and improves gas production efficiency includes a vertical well, an upper horizontal well and a lower horizontal well, and the upper horizontal well and the lower horizontal well are parallel to each other and extend along the same direction, They are all in communication with the vertical well, and the lower horizontal well is connected to the bottom side of the vertical well.

In some specific embodiments, the upper horizontal well is 30-40 meters away from the lower horizontal well.

In some other specific embodiments, the length of the upper horizontal well and the lower horizontal well is 600 to 800 meters.

The present invention uses the above-mentioned double horizontal wells to improve the physical properties of the reservoir space and improve the gas production efficiency, comprising the following steps: step 1) determining the land blocks rich in coalbed methane and shale gas;

Step 2), first drill a vertical well, drill to the bottom of the coalbed methane and shale gas layers, and then start to build up at the bottom of the vertical well. Using combined dynamic drilling tools, the dogleg angle of the build-up section is designed to be 4.5°/30m, and the section design It is a single circular arc profile, and the horizontal well is drilled;

Step 3), drilling the upper horizontal well 30-40 meters above the lower horizontal well.

In a specific implementation process, the upper horizontal well may be more than two horizontal wells arranged in parallel and extending in one direction.

The present invention uses the above-mentioned double horizontal wells to improve the physical properties of the reservoir space and improve the gas production efficiency, comprising the following steps: step 1) determining the land blocks rich in coalbed methane and shale gas;

Step 2), first drill a vertical well, drill to the bottom of the coalbed methane and shale gas layers, and then start to build up at a distance of 30-40 meters from the bottom of the vertical well. Using combined dynamic drilling tools, the dogleg angle of the build-up section is designed to be 4.5° /30m, the profile is designed as a single arc profile, and the horizontal well is drilled;

Step 3), build up at 30-40 meters from the bottom of the vertical well, use combined dynamic drilling tools, design the dogleg angle of the buildup section to be 4.5°/30m, and design the profile as a single arc profile, and drill the horizontal well.

Step 4) Fracturing the upper horizontal well and the lower horizontal well. The specific fracturing process is: firstly fracturing the lower horizontal well section. Since the length of the horizontal section is 600-800 meters, the interval between the fracturing sections is set at 60-80 meters, which means that the lower horizontal section is divided into ten sections for fracturing, and the fracturing is from the farthest end of the horizontal section to the vertical well section. start in sequence.

When the horizontal section is 800 meters, the interval between fracturing sections is set to 80 meters. Then the fracturing well section is 800-720 meters, 720-640 meters, 640-560 meters, 560-480 meters, 480-400 meters, 400-320 meters, 320-240 meters, 240- 160-meter section, 160-80-meter section, and 80-0-meter section. First of all, perforate it (enter the perforator, shoot the casing, cement sheath, until the coal or shale layer, open the channel for the gas to flow into the wellbore, called perforation), the perforator used for perforation is The bullet-type perforator uses 102 guns and 127 bullets, and a 60-degree phase angle is used for perforating, with 16 holes/m. Next, start fracturing, with displacement of 2.2-2.4m ³ /min, fluid volume in each section ranging from 800-1200m ³ , proppant dose of 100-200t in each section, mainly 40/70 mesh proppant, average sand ratio 3%-5%.

Then, the upper horizontal well is also fractured.

For relatively thin (below 30 meters) coal seams and shale beds, only improving the reservoir properties on the plane can solve the problem, but for relatively thick (more than 30 meters) coal seams and shale beds, only improving the plane The physical properties of the reservoir cannot be resolved in space. The double horizontal well drilling and fracturing method of the present invention not only improve the physical properties of the reservoir in the plane but also in the three dimensions, improve the physical properties of the reservoir in space, and achieve the purpose of increasing the gas production.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (9)

1. one kind is improved reservoir space physical property and improves the dual horizontal well of gas production efficiency, it is characterised in that include straight well, upper level Well and lower horizontal well, described upper horizontal well and lower horizontal well be parallel to each other and extend along same direction, its all with described straight well Connection, described lower horizontal well is connected to the side, bottom of described straight well.

A kind of dual horizontal well improving reservoir space physical property and improving gas production efficiency, its feature exists In, described upper horizontal well is apart from described lower horizontal well 30-40 rice.

A kind of dual horizontal well improving reservoir space physical property and improving gas production efficiency the most according to claim 1 or claim 2, its feature Being, the horizontal section length of described upper horizontal well and lower horizontal well is 600 to 800 meters.

4. one kind improve reservoir space physical property and improve gas production efficiency dual horizontal well building method, it is characterised in that include with Lower step: step 1) determine the plot containing abundant coal bed gas, shale gas；

Step 2), subdrilling a bite straight well, it is drilled into coal bed gas, the lower section of shale gas-bearing formation, then starts deflecting in straight well bottom, utilize group Closing power drilling tool, design 4.5 °/30m of inclination section dog-leg severity, Section Design is single circular arc section, bores lower horizontal well；

Step 3), under distance, above horizontal well, 30-40 rice bores horizontal well.

5. utilize the dual horizontal well described in any one of claim 1 to 3 to improve reservoir space physical property and raising according to claim 4 The method of gas production efficiency, it is characterised in that described upper horizontal well be more than two mouthfuls that be arranged in parallel and extend to direction Horizontal well.

6. one kind improve reservoir space physical property and improve gas production efficiency dual horizontal well building method, it is characterised in that include with Lower step: step 1) determine the plot containing abundant coal bed gas, shale gas；

Step 2), subdrilling a bite straight well, it is drilled into coal bed gas, the lower section of shale gas-bearing formation, then starts at distance straight well bottom 30-40 rice Deflecting, utilizes assembly power drilling tool, designs 4.5 °/30m of inclination section dog-leg severity, and Section Design is single circular arc section, level on brill Well；

Step 3), in straight well bottom, 30-40 rice starts deflecting, utilizes assembly power drilling tool, design inclination section dog-leg severity 4.5 °/ 30m, Section Design is single circular arc section, bores lower horizontal well.

A kind of dual horizontal well structure side improving reservoir space physical property and improving gas production efficiency the most according to claim 6 Method, it is characterised in that described upper horizontal well is more than two mouthfuls horizontal wells that are that be arranged in parallel and that extend to a direction.

A kind of dual horizontal well structure side improving reservoir space physical property and improving gas production efficiency the most according to claim 6 Method, it is characterised in that upper horizontal well and lower horizontal well are carried out pressure break.

A kind of dual horizontal well structure side improving reservoir space physical property and improving gas production efficiency the most according to claim 8 Method, it is characterised in that first to lower net horizontal section pressure break, lower horizontal well is being carried out pressure break；Described upper horizontal well and lower horizontal well Horizontal section length be 600～800 meters, fracturing section spacing is scheduled on 60～80 meters, from horizontal segment from straight well distalmost end to close Straight well starts pressure break the most successively.