Fracturing sand prevention and water control pipe column and construction method

Abstract

The invention relates to a fracturing sand control water control tubular column and a construction method, the tubular column comprises a top suspension packer, a water replenishing filling valve and a plurality of groups of fracturing water control units, and each group of fracturing water control unit comprises a screen pipe, a switchable sliding sleeve used for spraying mortar and an automatic regulating valve used for controlling water and extracting oil. The method comprises the steps that the pipe column is assembled and tripped into all stratums, the openable and closable sliding sleeve is opened to pump mortar, and liquid near the stratums is sucked into the construction stratums to form a large-size and large-size crack supporting belt; after fracturing is finished, the water replenishing filling valve is closed, mortar is accumulated near the sliding sleeve and the screen pipe to form a blocking sand bridge, and a sand prevention layer is formed. The tubular column structure integrates jetting separate layer fracturing, sand prevention and water control, the stratum porosity permeability is improved, meanwhile, the problem of stratum sand production and water control can be effectively solved, repeated tripping of the tubular column is not needed, the operation risk is reduced, and the risk of stratum pollution is reduced.

Description

Technical Field

[0001] This invention relates to the field of downhole tools for oil and gas field development, specifically a fracturing sand control and water control tubing string and its construction method. Background Technology

[0002] In oilfield operations, oil wells, gas wells, horizontal wells, vertical wells, and directional wells all face sand control and water control challenges. Currently, downhole sand control tubing is a commonly used tool in oilfields. Its purpose is to allow crude oil to flow smoothly while effectively blocking solid particles such as formation sand, quartz, and ceramsite, preventing them from entering the pipeline and causing blockages or equipment damage. However, while sand control tubing uses a filter medium for sand control, it cannot control water, thus failing to simultaneously fulfill both sand control and water control functions. There are existing solutions that add water control valves to sand control screens, but these solutions are functionally limited and inconvenient to use. Furthermore, they require multiple tripping operations, resulting in long operation times and significant risks. Summary of the Invention

[0003] To address the aforementioned problems, this invention aims to provide a fracturing sand control and water control tubing string and its construction method. To achieve this objective, the technical solution adopted by this invention provides a fracturing sand control and water control tubing string, including a top-mounted packer for suspending the entire tubing string. Starting from the top-mounted packer, several sets of fracturing water control units are sequentially arranged from top to bottom. Each set of fracturing water control units includes a screen pipe and a switchable sliding sleeve for spraying mortar. A through nozzle I is provided on the side wall of the switchable sliding sleeve. Inside the switchable sliding sleeve corresponding to the position of nozzle I, an axially movable ball seat liner is provided. The diameter of the ball seat liner used in each set of fracturing water control units, and the diameter of the corresponding soluble ball, decreases sequentially from top to bottom.

[0004] Initially, the outer wall of each ball seat inner liner seals each nozzle I; after the ball is thrown, the ball seat inner liner moves downward and opens nozzle I, allowing mortar nozzle I to enter the formation.

[0005] The upper and lower outer walls of the ball seat inner bushing are sealed to the inner wall of the switchable sliding sleeve through a sealing element, thus sealing the upper and lower ends of nozzle I.

[0006] The outer wall of the ball seat inner bushing is detachably connected to the inner wall of the switchable sliding sleeve via shear pins. Below the top suspension seal, a water filling valve is installed, with a filter layer containing quartz and ceramic particles inside its valve body. A nozzle II is also located on the side wall of the valve body. Inside the valve body corresponding to the position of nozzle II, there is an axially movable differential pressure piston. The lower end of the differential pressure piston is connected to the inner wall of the valve body via a return spring. The tubing pressure pushes the differential pressure piston downwards, opening nozzle II, allowing filtered water to enter the annulus.

[0007] Each fracturing water control unit also includes an automatic regulating valve for water control and oil production. The automatic regulating valve is located between the screen pipe and the switchable sliding sleeve. The valve body side wall and outer cavity of the automatic regulating valve are respectively provided with channels, and valve plates are provided in the channels. The valve plates are provided with openings that communicate with the channels. Oil- and water-expanding materials are respectively provided on the upper and lower sides of the valve body.

[0008] The top-mounted packer also includes a service tool that can be lowered in. The service tool has a switch lug for lifting the inner bushing of the ball seat to close the switchable slide sleeve, or a grinding bit for cleaning.

[0009] This invention also provides a fracturing sand control and water control construction method, comprising:

[0010] Step 1: Connect and assemble any of the aforementioned fracturing sand control and water control tubing strings in sequence, and lower them into each construction stratum;

[0011] Step two: Insert soluble balls that match a certain set of fracturing water control units to open the corresponding switchable sliding sleeve, then pump in mortar, increase the pressure and open the water filling valve; when the mortar reaches a certain speed, the outside of the switchable sliding sleeve will draw the liquid near its layer into the construction formation due to the Bernoulli equation principle; quartz and ceramsite will form a fracture support zone of a certain scale in this layer, which is used for fracturing and remodeling the formation;

[0012] Step 3: After fracturing is completed, the discharge rate decreases and the pressure inside the tubing also decreases. The water supply valve automatically closes, the mortar velocity decreases, and the mortar accumulates near the sliding sleeve and screen tube to form a sand-blocking bridge, forming a sand-proof layer for later production, thereby achieving the effect of controlling sand with sand.

[0013] The process includes step four: after all formations have been constructed, a service tool is lowered to flush the sand out of the tubing to the bottom of the well, and then all the ball-dropping switchable sleeves are pulled up to close. This completes the construction. Compared with existing technologies, this invention uses switchable sleeves to spray mortar to form a fracture support zone, achieving formation fracturing and transformation. Furthermore, it utilizes a water filling valve to accumulate near the sleeves and screen pipes, forming a sand-blocking bridge and creating a sand-control layer. This integrates jet fracturing, sand control, and water control into the tubing structure, improving formation porosity and permeability while effectively preventing sand and water production. It allows for production without moving the tubing after fracturing, eliminating the need for multiple tubing trips, reducing operational risks, saving operating costs and time, and minimizing the risk of formation contamination. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the switchable sliding sleeve;

[0015] Figure 2 A schematic diagram of the water filling valve;

[0016] Figure 3This is a schematic diagram of the water control valve.

[0017] Referring to the attached diagram, 11 upper connector of the sliding sleeve, 12 outer cylinder of the sliding sleeve, 13 inner bushing of the ball seat, 14 nozzle I, 15 lower connector of the sliding sleeve; 21 upper connector of the valve body, 22 outer cylinder of the valve body, 23 nozzle II, 24 differential pressure piston, 25 return spring, 26 lower connector of the valve body; 31 oil-swellable material, 32 valve seat, 33 valve plate, 34 water-swellable material. Detailed Implementation

[0018] The present invention will now be further described with reference to the accompanying drawings.

[0019] See Figures 1 to 3 , Figures 1 to 3 The illustration shows an embodiment of the present invention. The fracturing sand control and water control tubing includes a top suspension packer for suspending the entire tubing. Starting from the top suspension packer, several sets of fracturing water control units are arranged sequentially from top to bottom. Each set of fracturing water control units includes a screen pipe and an openable sliding sleeve for spraying mortar.

[0020] The overall structure of the fracturing sand control and water control tubing string is as follows: a top-suspended packer, a water filling valve, a closed screen pipe 1, a switchable sliding sleeve 1, an automatic regulating valve 1, a double-layer switchable screen pipe 2, a switchable sliding sleeve 2, an automatic regulating valve 2, a double-layer switchable screen pipe 3, a switchable sliding sleeve 3, an automatic regulating valve 3, ... a double-layer switchable screen pipe N, a switchable sliding sleeve N, an automatic regulating valve N, and a service tool and N soluble balls of different diameters located within the top-suspended packer.

[0021] See Figure 1 The switchable sleeve is a tubular structure open at both ends, consisting of an upper sleeve connector, an outer sleeve body, and a lower sleeve connector connected axially via threads and several sealing elements (O-rings). A through nozzle I is located on the side wall of the outer sleeve body. Inside the switchable sleeve corresponding to the nozzle I, there is an axially movable ball seat liner. The upper end of the ball seat liner has a ball seat structure that forms a seal when a matching soluble ball is inserted, increasing the wellbore pressure and thus pushing the ball seat liner downwards to open nozzle I.

[0022] Initially, the outer walls of the upper and lower ends of the ball seat bushing are sealed to the inner wall of the switchable sleeve through a sealing element (O-ring), thereby sealing the upper and lower ends of nozzle I and preventing the interior and exterior annulus of the switchable sleeve from communicating.

[0023] Preferably, the outer wall of the ball seat inner bushing is detachably connected to the inner wall of the switchable sliding sleeve via a shear pin; the ball seat inner bushing can only descend when the pressure reaches a preset value and cuts the shear pin, thus preventing accidental activation.

[0024] Preferably, the upper outer wall of the lower sliding sleeve connector is sealed to the lower outer wall of the ball seat liner, thus placing the upper end face of the lower sliding sleeve connector inside the lower section of the ball seat liner. When the lower end of the ball seat liner contacts the upper end face of the lower sliding sleeve connector after descending, they form a limiting structure, preventing the ball seat liner from continuing to descend. The diameter of the ball seat liner and the corresponding soluble ball used in each fracturing water control unit decreases sequentially from top to bottom. A soluble ball of any diameter can seal the ball seat liner of its corresponding switchable sliding sleeve. Initially, the outer walls of each ball seat liner from top to bottom seal each nozzle I; after the ball is dropped, the ball seat liner descends and opens nozzle I, allowing the mortar nozzle I to enter the formation. The switchable sliding sleeve serves as an effective channel for mortar, and the negative pressure generated by high-speed injection separates the upper and lower units, achieving the purpose of stratified fracturing.

[0025] See Figure 2 The water filling valve is also a tubular structure with openings at both ends. The valve body is formed by the upper valve body connector, the outer cylinder of the valve body, and the lower valve body connector connected together along the axial direction by threads and several sealing elements (O-rings). The valve body has an internal filter layer that can isolate the quartz sand or ceramic particles in the tubing, preventing them from entering the annulus outside the valve body.

[0026] The valve body is also equipped with nozzle II on its side wall. Inside the valve body corresponding to the position of nozzle II, there is a differential pressure piston that can move axially. The lower end of the differential pressure piston is connected to the upper end of the return spring, and the lower end of the return spring is connected to the upper end face of the lower connector of the valve body. The outer walls of the upper and lower ends of the differential pressure piston are also sealed with the inner wall of the outer cylinder of the valve body through several sealing elements (O-rings), thereby sealing the upper and lower ends of nozzle II, so that the interior of the water filling valve is not connected to the external annulus.

[0027] As the pressure inside the tubing increases, it pushes the differential pressure piston downward and opens nozzle II, allowing filtered water to enter the annulus through nozzle II. When the pressure decreases, the compressed return spring drives the differential pressure piston upward and closes nozzle II. The water replenishment valve is used as a water replenishment device during fracturing with a switchable sliding sleeve.

[0028] See Figure 3The automatic regulating valve includes a valve body structure similar to that of a water filling valve, and also includes an outer cavity, a valve plate, and an inner liner. Channels are provided on the side walls of the valve body and the outer cavity, with the valve plate located within each channel. The valve plate has openings communicating with the channels. Oil- and water-swellable materials are respectively provided on the upper and lower sides of the valve body. When the liquid flowing into the automatic regulating valve is water, the volume of the water-swellable material increases within the valve seat, pushing the valve plate upwards and closing the channel, preventing water from entering the wellbore. When the liquid is oil, the volume of the oil-swellable material increases, pushing the valve plate downwards and opening the channel, allowing the liquid (oil) to flow into the wellbore, thus achieving water control for oil production. The automatic regulating valve is connected to the upper part of the screen pipe and forms a fracturing production unit together with the closed screen pipe and the ball-operated sliding sleeve.

[0029] In addition, the top-suspended packer also contains a service tool that can be lowered. The service tool has a switch lug for lifting the ball seat liner to close the switchable sliding sleeve, and a grinding bit for cleaning. After the entire tubing string is installed, the service tool is lowered. When it reaches the ball seat liner position, the pump is started to circulate and the remaining soluble balls are drilled out using the grinding bit. After cleaning to the bottom of the well, the service tool is slowly raised, and the switch lug applies force to the ball seat liner and its corresponding mechanism, closing the sliding sleeves at each layer.

[0030] Before construction, review the well completion design data, collect relevant data for the target well, and prepare the necessary sand control tools and hand tools. Based on the casing shoe and casing cementing quality, preliminarily determine the quantity and piping length of the top-mounted packer, water filling valve, double-layer switchable / closed screen, switchable sliding sleeve, automatic regulating valve, and service tools.

[0031] During construction, based on the required equipment quantity for sand control operations, coordinate a suitable site for placing tools to facilitate subsequent connection and hoisting operations. Simultaneously, inspect the hoisting tools. Then, lay the pipes layer by layer according to the lowering sequence, measuring the tool dimensions, paying attention to the tool's orientation. Finally, hoist the tools out of the long cage and arrange them in order.

[0032] Based on this, the setting position of the packer and the position of the service tools are calculated and determined according to the measured casing length. Appropriate blind pipe screens and casing subs are selected to complete precise piping. To facilitate string installation and reduce wellhead operation time for sand control, the required subs can be pre-connected to the corresponding tools on-site. During construction, the outer sand control string is installed. Wellhead tools, including the screen, insert plate, cup holder, and hand-held slips, are hoisted to the drilling platform in advance. The outer sand control string is then installed sequentially according to the precise piping schedule. After connecting the top packer, the fracturing sand control and water control string described in the aforementioned embodiment is run into each formation; and the setting position is confirmed.

[0033] By introducing the soluble ball N, the corresponding sized switchable sleeve N is opened, mortar is pumped in, and the discharge rate is gradually increased. As the pressure rises, the water filling valve is opened. When the mortar through the switchable sleeve reaches a certain velocity (which varies depending on the formation conditions), the outer side of the switchable sleeve, due to Bernoulli's principle, will draw liquid near the switchable sleeve layer into the formation being treated. As fracturing progresses, quartz and ceramsite will form a large-scale fracture support zone in this layer, which can be used for fracturing and formation modification.

[0034] As fracturing ends and the mortar flow rate decreases, the pressure inside the tubing also decreases, and the water filling valve automatically closes. The reduced mortar velocity causes it to accumulate near the sliding sleeve and screen tube, forming a sand-blocking bridge and creating a sand-prevention layer for later production, thus achieving the effect of controlling sand with sand.

[0035] After the annulus is filled to a certain extent and the fracturing and sand control operations are completed, the next layer of construction will proceed. Once all layers are completed, service tools will be lowered to flush the sand out of the tubing to the bottom of the well, and all ball-feeding switchable sleeves will be closed. This completes the construction process.

[0036] The embodiments of the present invention have been described above with reference to the accompanying drawings and examples. The structures given in the embodiments do not constitute a limitation of the present invention. Those skilled in the art can make adjustments as needed, and various modifications or variations within the scope of the appended claims are all within the scope of protection.

Claims

1. A fracturing sand control and water control tubing string, comprising a top suspension packer for suspending the entire tubing string, characterized in that: Starting from the top-suspended packer, several sets of fracturing water control units are arranged sequentially from top to bottom. Each set of fracturing water control units includes a screen pipe and an openable sliding sleeve for spraying mortar. The side wall of the switchable sleeve is provided with a through nozzle I; inside the switchable sleeve corresponding to the position of nozzle I, there is a ball seat inner bushing that can move axially. The diameter of the ball seat liner and the corresponding soluble ball used in each fracturing water control unit decreases sequentially from top to bottom. Initially, the outer wall of each ball seat liner seals each nozzle I. After the ball is dropped, the ball seat liner moves downward and opens the nozzle I, allowing the mortar nozzle I to enter the formation.

2. The fracturing sand control and water control tubing string according to claim 1, characterized in that: The upper and lower outer walls of the ball seat inner bushing are sealed to the inner wall of the switchable sliding sleeve through a sealing element, thus sealing the upper and lower ends of nozzle I.

3. The fracturing sand control and water control tubing string according to claim 1 or 2, characterized in that: The outer wall of the ball seat bushing is detachably connected to the inner wall of the switchable sliding sleeve via shear pins.

4. The fracturing sand control and water control tubing string according to claim 1, characterized in that: Below the top suspension seal, there is also a water filling valve, whose valve body has a filter layer of quartz stone and ceramic particles; the side wall of the valve body is also equipped with nozzle II, and inside the valve body corresponding to the position of nozzle II, there is a differential pressure piston that can move axially. The lower end of the differential pressure piston is connected to the inner wall of the valve body through a return spring; the tubing pressure pushes the differential pressure piston down to open nozzle II, and the filtered water enters the annulus through nozzle II.

5. The fracturing sand control and water control tubing string according to claim 1, characterized in that: Each fracturing water control unit also includes an automatic regulating valve for water control and oil production. The automatic regulating valve is located between the screen pipe and the switchable sliding sleeve. The valve body side wall and outer cavity of the automatic regulating valve are respectively provided with channels, and valve plates are provided in the channels. The valve plates are provided with openings that communicate with the channels. The upper and lower sides of the valve body are respectively provided with oil- and water-swellable materials.

6. The fracturing sand control and water control tubing string according to claim 1, characterized in that: The top-mounted packer also includes a downable service tool with a switch lug for lifting the ball seat bushing to close the switchable slide sleeve; and / or a grinding bit for cleaning.

7. A fracturing sand control and water control construction method, characterized in that... include: Step 1: Sequentially connect and assemble the fracturing sand control and water control tubing as described in any one of claims 1-6, and lower it into each construction stratum; Step 2: Insert soluble balls to open the corresponding switchable sliding sleeve, then pump in mortar, increase the pressure and open the water filling valve; when the mortar reaches a specific speed, the outside of the switchable sliding sleeve will draw the liquid near its layer into the construction stratum due to the Bernoulli equation principle; quartz and ceramsite will form a large-scale fracture support zone in this layer, which is used for fracturing and remodeling the stratum. Step 3: After fracturing is completed, the discharge rate is reduced and the pressure inside the tubing also decreases. The water filling valve is closed, the mortar velocity decreases, and the mortar accumulates near the sliding sleeve and screen pipe to form a sand-blocking bridge, thus forming a sand-prevention layer and achieving sand control with sand.

8. The construction method according to claim 7, characterized in that: It also includes step four, after all the construction strata are completed, the service tool is lowered to flush the sand in the tubing to the bottom of the well, and all the ball-dropping switchable sleeves are pulled up to close.

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