CN112282720B - Site construction method of fishbone well and corresponding matched equipment - Google Patents

Abstract

The application discloses a site construction method of a fishbone well, which comprises the following steps: determining a construction point and determining the conditions of a submarine hydrate well position, a frozen soil layer and a hydrate sandstone layer; determining a downhole operation pipe column structure according to pressure change in a logging curve, and determining a fish bone spur completion range according to reservoir hole seepage characteristics and a development scheme; according to the structure of the underground operation pipe column and the well completion area, the density of the fishbone is regulated, and the drilling direction of the fishbone branch pipe, the installation positions and the number of the fishbone nipple are determined; determining pumping pressure to ensure that the position of the last fishbone nipple reaches the minimum pressure for normal operation; starting pump circulation to enable the last fishbone nipple to reach the minimum pressure for normal operation, and carrying out fishbone well reconstruction on the reservoir by all the fishbone nipples; the application uses ground pressurization to carry out branch pipe drilling operation, has less field construction procedures, short time, less large equipment use, small occupied area, low cost, large reconstruction density, controllable reconstruction depth, less working fluid consumption and small ground stress influence; the anisotropic reservoir has good yield increasing effect.

Description

An on-site construction method for fishbone wells and corresponding supporting equipment

Technical field

The invention relates to the technical field of drilling and completion, and in particular to an on-site construction method for fishbone completion of natural gas hydrate reservoirs and its corresponding supporting equipment.

Background technique

The burial depth of natural gas hydrate is shallow, usually located at 0 to 500m on the seabed, but its abundance is generally low, distributed over a large area, and locally enriched. It is necessary to increase the well density to increase the recovery rate, resulting in high development costs. During the offshore drilling process, due to factors such as complex formations and hydrate occurrence conditions, loose reservoirs can easily lead to problems such as well wall collapse and drill sticking. However, the deck area of offshore drilling platforms is limited, and the equipment used for measures such as hydraulic fracturing and well completion and production increase will be limited. However, these measures have many construction links and long operation times.

The existing fishbone drilling system only needs to be connected before being lowered into the well. Each fishbone tail pipe is equipped with 3-4 small-diameter drill pipes, and the front end of each small-diameter drill pipe is connected to a jet drill bit. When it is lowered to the predetermined position, the pump is turned on to pressurize the drill pipe. Under the action of the propulsion force, the small-diameter drill pipe turns to the guide rail and extends diagonally, and the hydraulic jetting operation is started to form a hole channel. However, the existing technology has the following problems: (1) Fracturing operations require multiple large fracturing pump units, sand mixing skids, and large amounts of fracturing fluid. However, the offshore drilling platform has a limited area and it is difficult to meet the placement requirements of the above equipment. ; (2) Hydrate reservoirs are widely distributed and have low abundance, resulting in a small effective sweep area for a single well and high development costs; (3) Hydrate reservoirs are complex, and downhole accidents are prone to occur during drilling and completion, with high risks and increased Operating costs; (4) Hydraulic fracturing construction uses a large amount of water, proppant and chemical additives, which can easily cause environmental pollution; (5) Hydraulic fracturing construction requires cementing, perforating, well cleaning and other operations before construction, resulting in a long construction period .

Contents of the invention

In order to solve the above problems, the present invention proposes an on-site construction method for natural gas hydrate fishbone wells and corresponding supporting equipment.

The on-site construction of the natural gas hydrate fishbone well of the present invention includes: determining the construction point, determining the seabed hydrate well location, frozen soil layer, and hydrate sandstone layer; determining the downhole operation string structure according to the pressure changes in the well logging curve, and determining the downhole operation string structure according to the pressure changes in the well logging curve. The reservoir porosity and permeability characteristics and development plan determine the fishbone completion range and working fluid performance; adjust the fishbone density according to the downhole operation string structure and completion area, determine the fishbone branch pipe drilling direction, and the fishbone sub-section Installation location and number; determine the pump pressure to ensure that the last fish spur sub-joint reaches the minimum normal working pressure; start the pump cycle to make the last fish spur sub-joint reach the normal working minimum pressure, and all fish spur sub-joints The fishbone well reconstruction will be carried out in this layer.

Furthermore, the normal operating minimum pressure reached at the last fish bone spur joint is 21MPa, that is, the minimum starting pressure. At this time, the nozzle consumption pressure is 2MPa.

Further, the method for adjusting the density of fish bone spines is to shorten or enlarge the spacing based on the length of a single root or short section.

Furthermore, each of the sub-joints has 3-4 lateral branches covering a 12-meter formation section, 25 fishbone joints can cover a 300-meter section of formation, and a total of 100 lateral branches have entered the formation for more than 1,200 meters.

Furthermore, the minimum pressure of each fish bone spur in the fish bone spur tool string is 21MPa during normal operation.

Furthermore, based on the reservoir porosity and permeability characteristics and the development plan, it was determined that the range of fishbone completion wells is the 300-500 meter section of the formation.

The on-site construction supporting equipment of the present invention includes: mud pump, slurry tank, jet fluid, fishbone branch pipe, mother pipe, hanger, tail pipe string, feeding pipe string, and casing.

Further, the fishbone completion pipe string includes a plurality of fishbone branch sub-sections, each fishbone branch sub-section includes a sand-blocking medium, an outer protective cover, a one-flow valve and a fishbone branch pipe, wherein the sand-blocking medium It is installed on the outer wall of the fish spur branch sub-section, and the outer protective cover is installed on the outer wall of the sand retaining medium. The fish spur branch sub joint, the sand retaining medium, the outer protective cover and the fish spur branch pipe are all tubular.

Further, the main pipe is matched to the size of the wellbore and includes a centralizer, which has holes at designated positions on the outer wall of the branch pipe for drilling of the branch pipe.

Further, the corresponding size and quantity are prepared according to the formation, and the fishbone branch pipes are lowered into the formation together with the mother pipe and suspended in the upper casing.

The on-site construction method of a fishbone well and corresponding supporting equipment provided by the present invention have the following beneficial effects: the on-site construction method of a fishbone well of the present invention uses ground pressure to perform drilling operations, and the on-site construction time is less than 0.5 days; the process Reduction can significantly reduce operating costs and improve economic indicators. Compared with the conventional horizontal well casing, cementing, drilling plugs, perforating, pipe scraping, well completion and production stimulation and other operation links, the present invention can moderately relax the harsh conditions of high cementing quality requirements for horizontal wells, and is different from conventional hydraulic pressure. The fracturing stimulation method also has many advantages. It does not require a fracturing pump unit, occupies a small area, and requires less fluid than the stimulation operation under the same conditions; it requires fewer pumps and irrigation than fracturing and acid fracturing; and it requires less fluid to enter the formation. The depth is adjustable within a range of less than 12m, and the formation penetration is controllable; the lower packer can be selected according to the stratum stratification needs to meet the requirements of the required stratification sections.

Description of the drawings

In order to explain the embodiments of the present application or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are some embodiments recorded in this application. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

Figure 1 is a flow chart of the on-site construction method of the fishbone well according to the embodiment of the present invention;

Figure 2 is a structural diagram of a fishbone well completion pipe string according to an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present application are clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the scope of protection of this application.

In addition, the following description of the embodiments refers to the accompanying drawings to illustrate specific embodiments in which the invention may be practiced. The directional terms mentioned in the present invention, such as "upper", "lower", "front", "back", "left", "right", "inside", "outside", "side", etc., are only Reference is made to the direction of the attached drawings. Therefore, the directional terms used are for the purpose of better and clearer description and understanding of the present invention, but do not indicate or imply that the device or component referred to must have a specific orientation, be in a specific orientation. construction and operation, and therefore should not be construed as limitations of the invention.

In the description of the present invention, it should be noted that, unless otherwise clearly stated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection. Ground connection, or integral connection; it can be a mechanical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium; it can be an internal connection between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood on a case-by-case basis.

The purpose of the present invention is to provide an on-site construction method for fishbone wells to solve the problems existing in the above-mentioned prior art and has the characteristics of good production increase effect, simple construction, short construction period, and low cost.

In order to make the above objects, features and advantages of the present invention more obvious and easy to understand, the on-site construction method of the fishbone well of the present invention will be further described in detail below with reference to Figure 1 .

The on-site construction method of the fishbone well of the present invention includes the following steps:

S101: Determine the construction site, seafloor hydrate well location, permafrost layer, and hydrate sandstone layer;

First, determine the construction sea area, initially understand the water depth, hydrate reservoir type, burial depth and other data, and determine the submarine hydrate well location, frozen soil layer, and hydrate sandstone layer.

S102: Determine the downhole structure of the operating pipe string based on the pressure change curve in the well logging curve, determine the fishbone completion range and working fluid performance based on the reservoir porosity and permeability characteristics and development plan;

Secondly, the downhole operation string structure is determined based on the formation pressure changes in the well logging curve, and then the completion area is selected based on the reservoir porosity and permeability characteristics and development plan to cover the 300-500 meter section.

The four lateral branches of each joint provided by the invention cover a 12-meter formation section, and the 25 fishbone joints can cover a 300-meter section of formation. A total of 100 lateral branches have accumulated into the formation for more than 1,200 meters.

S103: Adjust the density of fish bone spurs, and determine the drilling direction, installation position and number of fish bone spur branch pipes based on the length of the pup joint;

According to the structure of the downhole operation string and the completion area, adjust the density of fish spurs, shorten or enlarge the spacing in units of single or pup lengths, and determine the drilling direction of fish spur branch pipes and the installation position and number of fish spur pup joints. .

S104: Determine the pumping pressure so that the last fishbone branch pipe joint reaches the normal working minimum pressure of 21MPa;

According to the drilling direction of the fishbone branch pipe, the installation position and number of the fishbone sub-joints, determine the pump pressure required to ensure that the last fishbone branch pipe joint reaches the minimum normal working pressure, where the minimum normal working pressure is 21MPa; the nozzle consumes 2MPa.

S105: Start the pump cycle to make the last fishbone sub-joint reach the normal working minimum pressure of 21MPa, and all fishbone sub-joints will perform fishbone well reformation on the reservoir;

After inserting fish spurs to complete the well penetration, the pump is turned on for circulation. After the last fish spur sub-joint reaches the minimum normal operating pressure of 21MPa, all fish spur sub-joints are used to perform fish spur well stimulation on the reservoir.

In the present invention, the on-site construction supporting equipment that needs to be provided includes: mud pump, slurry tank, jet fluid, fishbone completion pipe string, mother pipe, hanger, liner string, feed pipe string, casing .

Referring to Figure 2 below, the fishbone completion pipe string used in the on-site construction supporting equipment provided by the present invention will be described in detail.

As shown in Figure 2, the fishbone completion pipe string is composed of multiple fishbone branch sub-sections (1). The fishbone branch sub-section (1) contains sand retaining media (2), outer protective cover (3), single flow The valve (4) and the fishbone branch pipe (5), the sand retaining medium (2) are installed on the outer wall of the fishbone branch nipple (1), and the outer protective cover (3) is installed on the outer wall of the sand retaining medium (2) , the fishbone branch sub-section (1), the sand retaining medium (2), the outer protective cover (3) and the fishbone branch pipe (5) are all tubular.

The mother pipe used in the on-site construction supporting equipment of the present invention is matched with the wellbore and includes centralizers, floating hoops, floating shoes and other tools. There are holes at designated positions for drilling branch pipes.

In order to cooperate with the fishbone completion pipe string, the present invention also requires the use of running tools, connection buckle type confirmation, buckle change processing and pipe string unfastening, and corresponding sizes and quantities are prepared according to the formation. The fishbone branch pipes are installed with the parent pipe. The pipes are lowered into the formation together and suspended in the upper casing.

The pulping tank used in the present invention refers to adding corresponding abrasives or acid solutions according to the properties of the formation to prepare branch pipe drilling fluid for use in pressurized drilling of fish bone completion wells. At the same time, in order to meet the needs of on-site construction, it is also necessary to provide construction labor protection supplies; at the same time, there are on-site service engineers at the construction site.

The present invention will be further described in detail below with reference to specific embodiments.

Example 1:

1) Well #2 of the XX Oilfield in North America. The production layer is the Texas Cretaceous limestone with the highest formation hardness in the world. It is a low-pressure crude oil production well. 15 fishbone joints were run into the operation, and the construction displacement was 8.1 barrels/minute. , squeeze into the formation acid about 2,000 barrels, squeeze for 4 hours, and the maximum construction pump pressure is limited to 3,250Psi.

2) Fish bone bone application conditions;

Open hole wellbore; wellbore size: 8-1/2″ or 6″--6-1/2″; normal operating pressure of the tool is 21MPa, pressure resistance 35MPa; conventional tool formation downhole temperature does not exceed 175°C; suitable for vertical wells and inclined wells Wells, directional wells or horizontal wells; the requirements for the dogleg of the wellbore are the same as for running casing of the same size; horizontal wells can take into account the comprehensive mining of upper and lower layers; the fishbone needle tube enters the ground to a depth of 12 meters; the hole density does not exceed 4 ( Or 3)/12 meters; all fishbone needle tubes need to enter the formation at the same time.

3) The engineer will give the construction design plan;

4) According to the design plan, workers work on the construction site;

On-site work tool assembly, fishbone tool downhole, and acid pumping operations.

5) On-site construction working parameters:

Fish bone pressure in the last section: 21MPa

Nozzle consumption pressure: 2MPa

Coverage: 300-500 meters

Well fluid loss rate: 6 barrels/minute

Liquid level depth before operation: 5200-5400ft (start grouting from bottom to 5000ft)

Acid injection method: squeeze method (lower than formation fracture pressure)

Acid solution name: 15% HCL + preservative + additives

Acid squeezing operation time: 5:38--8:38, liquid replacement: 8:38--8:58, total 3:20

Squeezing acid displacement: 8.1 barrels/min, maximum operating displacement: 10 barrels/min (liquid replacement)

Amount of acid squeezed in: 1915 barrels, total injected liquid volume: 2058 barrels

Maximum ground pump pressure: 3250psi, minimum ground pump pressure: 100psi

Intermediate pressure starting time: 6:52 (the corresponding needle advance operation time took 74 minutes)

The amount of acid consumed when all the needle tubes enter the formation: 599.4 barrels (95.3 cubic meters)

Acid liquid excess margin coefficient: 3.2

6) Precautions

Construction precautions: Cooperation between the hanger and the top packer seat seal and the fishbone tool;

Precautions for tools: When running a pipe string in the open hole, the guide shoe must have the drilling function. When the pipe string is blocked, try not to turn on the pump to circulate the mud. Priority is given to using the method of lifting and lowering or rotating the pipe string to drill.

7)Results

It was confirmed that the fish bone spur can be safely implemented underground, and the operation risk is within the acceptable range; it was confirmed that the liner can be rotated and safely lowered to the bottom of the well during the pipe string running process; the pressure chart read that the 12-meter needle pipe completely entered the formation, and it was confirmed that the The forward pulser works normally; it is confirmed that the backbone anchor is successfully seated; the acid circulation valve is closed according to the predetermined plan; the penetration rate and the amount of construction pumping liquid required for on-site operations are successfully predicted through indoor test testing; 30 sets of forward Pulse valve.

Using the on-site construction equipment of the fishbone tube well of the present invention, the oil reservoir can be connected simply, accurately and efficiently; the operation uses a 4.5-inch pipe string to connect 15 fishbone tail pipes and installs 3 open hole reverse thrust anchors; thus enabling the pump to be started The job went smoothly as planned. The circulation valve was closed after encountering acid, and the injection operation was started, and 60 branches were successfully opened; the overall operation was successfully completed according to the original plan; when the fishbone needle tube was completely released, the pressure gauge showed back pressure; the entire pump operation lasted about 5 hours, including injection Operation and liquid flowback.

The difficulty and significance of the present invention in solving the existing technical problems are: (1) Natural gas hydrate mainly contains methane, which is a kind of green energy and has been listed as the 173rd mineral species in my country. When decomposed per unit volume, under standard conditions It can generate up to 164 units of natural gas in volume, and there is a large amount of natural gas hydrate in the deep sea of my country's South China Sea, which is of great significance to alleviating my country's total energy demand. (2) Fishbone completion reservoir stimulation has high effectiveness. The main wellbore can effectively increase the exposed area of the hydrate reservoir through multiple branch pipes, thereby increasing natural gas production. The main wellbore can adjust the direction and length of the branch pipes according to the characteristics and needs of the reservoir. (3) The fishbone completion construction process is simple. The tailpipe string is the same as conventional and equipped with tailpipe hanger slips. The production stimulation operation can be completed while completing the well, without the need for cementing, perforating, well cleaning and fracturing operations. (4) Fishbone well completion can reduce operating costs. Conventional reservoir stimulation operations have many processes, long operation times, many large-scale equipment on the ground, and complicated processes. In contrast, fishbone completion uses surface pressure for drilling operations, and the on-site construction time is less than 0.5 days and does not require multiple units. The fracturing pump unit occupies a small area and has a simple operating process, which can significantly reduce operating costs. (5) Fish bone spur completion effectively protects the reservoir. During the production stimulation operation of hydraulic fracturing, it is easy to cause damage to the reservoir, but the fishbone completion technology can effectively protect the reservoir. (6) Fishbone well completion has little impact on the environment. By reducing the operating process and construction time, the operation consumes less water, reducing the impact on the environment, while avoiding the flowback and treatment of traditional hydraulic fracturing fluids.

Although the preferred embodiments of the present application have been described, those skilled in the art will be able to make additional changes and modifications to these embodiments once the basic inventive concepts are apparent. Therefore, it is intended that the appended claims be construed to include the preferred embodiments and all changes and modifications that fall within the scope of this application. Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. In this way, if these modifications and variations of the present application fall within the scope of the claims of the present application and equivalent technologies, the present application is also intended to include these modifications and variations.

Claims (8)

1. An on-site construction method for fishbone wells, which method includes: Determine the construction site and determine the location of submarine hydrate wells, frozen soil layers, and hydrate sandstone layers; Determine the downhole operation string structure based on the pressure changes in the well logging curve, and determine the fish bone completion range and working fluid performance based on the reservoir porosity and permeability characteristics and development plan; According to the structure of the downhole operation string and the completion area, adjust the density of fish spurs, determine the drilling direction of fish spur branch pipes, and the installation position and number of fish spur sub-sections; Determine the pump inlet pressure to ensure that the last fish bone spur joint reaches the minimum pressure for normal operation; Start the pump cycle to make the last fishbone sub-joint reach the normal working minimum pressure, and all fishbone sub-joints will perform fishbone spur well reformation on the reservoir; On-site construction supporting equipment used in the on-site construction method includes: mud pump, slurry tank, jet fluid, fishbone branch pipe, mother pipe, hanger, tail pipe string, feeding pipe string, and casing; Among them, the fishbone completion pipe string used includes a plurality of fishbone branch sub-sections. Each fishbone branch sub-section includes a sand-blocking medium, an outer protective cover, a one-flow valve and a fishbone branch pipe. Among them, the sand-blocking medium It is installed on the outer wall of the fish spur branch sub-section, and the outer protective cover is installed on the outer wall of the sand retaining medium. The fish spur branch sub joint, the sand retaining medium, the outer protective cover and the fish spur branch pipe are all tubular. 2. The on-site construction method as claimed in claim 1, wherein the normal operating minimum pressure reached at the last fish bone spur joint is 21 MPa, that is, the minimum starting pressure, and the nozzle consumption pressure at this time is 2 MPa. 3. The on-site construction method according to claim 1, wherein the method for adjusting the density of fish bone spurs is to shorten or enlarge the spacing based on the length of a single bone or a short section. 4. The on-site construction method as claimed in claim 3, wherein each of the short joints has 3-4 side branches covering a 12-meter formation section, and 25 fishbone joints can cover a 300-meter section of formation, a total of 100. The lateral branches have accumulated into the formation for more than 1200m. 5. The on-site construction method as claimed in claim 3, wherein the minimum pressure of each fish bone spur in the fish bone tool string is 21 MPa during normal operation. 6. The on-site construction method as claimed in claim 1, wherein the range of fishbone completion is determined to be a stratum of 300-500 meters based on the porosity and permeability characteristics of the reservoir and the development plan. 7. The on-site construction method according to claim 1, characterized in that the main pipe is matched to the size of the wellbore and includes a centralizer, a floating hoop, a floating shoe, and a hanging tool. There are holes at designated positions on the outer wall of the branch pipe for branching. Pipe drilling. 8. The on-site construction method according to claim 7, characterized in that the fishbone branch pipes of corresponding sizes and quantities are prepared according to the stratum, and the branch pipes are lowered into the stratum together with the mother pipe and suspended. in the upper casing.