A high-temperature shale gas long horizontal well drilling temperature control system and method

Abstract

The application discloses a high-temperature shale gas long horizontal well drilling temperature control system and method, and belongs to the technical field of drilling engineering. The system comprises a drilling tool assembly, a ground cooling device, a top drive, a mud pump, a solid control device and the like. The drilling tool assembly comprises a rotary steering tool, a screw motor and a drill pipe. Meanwhile, the application also discloses a high-temperature shale gas long horizontal well drilling temperature control method. The application adopts theoretical analysis and fitting methods combined with field test data to simulate the bottom hole circulating temperature of the drilling fluid. By adjusting the drilling fluid density, the mud pump displacement, the drilling tool assembly and the number of revolutions of the drilling tool assembly, the application simulates and observes the influence of different parameters on the bottom hole circulating temperature of the drilling fluid, thereby providing a reference basis for optimizing the field construction parameters of deep high-temperature drilling.

Description

Technical Field

[0001] This invention relates to the field of drilling engineering technology, and in particular to a temperature control system and method for drilling long horizontal wells in high-temperature shale gas. Background Technology

[0002] Currently, most technologies and equipment used for bottomhole cooling of drilling fluids employ surface cooling methods, which involve lowering the temperature of the drilling fluid entering the well to reduce its temperature within the wellbore. However, calculations based on relevant theoretical models and field data reveal that surface cooling devices can only partially reduce the bottomhole circulating temperature of the drilling fluid. Further optimization of drilling parameters is needed to achieve more effective downhole temperature control.

[0003] At present, researchers have conducted research on temperature control methods through extensive theoretical analysis and fitting of field downhole temperature test data, and carried out sensitivity analysis on the influence of various drilling process parameters on the bottom hole circulation temperature of drilling fluid.

[0004] There is an urgent need for a high-temperature shale gas long horizontal well drilling temperature control system and method. Summary of the Invention

[0005] The purpose of this invention is to overcome the deficiencies in the existing technology and provide a high-temperature shale gas long horizontal well drilling temperature control system and method. It uses theoretical analysis and fitting of field test data to simulate the bottom hole circulation temperature of drilling fluid. By adjusting the drilling fluid density, mud pump discharge rate, top drive speed, drill string combination, etc., the effects of different parameters on the bottom hole circulation temperature of drilling fluid are simulated and observed, providing a reference for optimizing field construction parameters for deep high-temperature drilling.

[0006] The embodiments of the present invention are implemented as follows:

[0007] On the one hand, the embodiments of this invention provide a high-temperature shale gas long horizontal well drilling temperature control system, including a drill string assembly 114, a surface cooling device 118, a top drive 113, a mud pump 110, and a solids control device 103. The drilling fluid returning from the drilling nozzle 101 enters the solids control equipment 103 along the overhead trough 102. After removing some of the solids, it flows through the conical tank 104 at the bottom of the solids control equipment 103. The conical tank is connected to the vertical heat exchanger 107 via valve 105, centrifugal pump 106, and pipeline 117. The drilling fluid enters the vertical heat exchanger 107 via valve 105, centrifugal pump 106, and pipeline 117. After primary cooling, the resulting low-temperature drilling fluid returns to the upper mud tank 109. Through pipeline 117, the drilling fluid enters the mud pump 110, then through the riser 111 into the hose 112, and then through the top drive 113 into the drill string assembly 114. After circulating to the bottom of the well, the drilling fluid is recirculated through the wellbore 116 via the drilling nozzle 101, repeating the above process. The ground cooling device includes valve 105, centrifugal pump 106, vertical heat exchanger 107, cooling tower 108, and pipeline 117. The relative positions of each component should be referenced in relevant petroleum standards. The cooling medium and drilling fluid in the primary vertical heat exchanger 107 exchange heat in parallel. The vertical heat exchanger 107 is entirely externally mounted, offering advantages such as small footprint, high efficiency, and convenient maintenance. The cooling tower 108 cools the high-temperature cooling medium discharged from the primary vertical heat exchanger 107, enabling the recycling of the cooling medium and overcoming the problem of insufficient or unreliable water supply on the drilling platform. The cooled drilling fluid, pumped by two mud pumps 110 through riser 111, hose 112, and top drive 113, is injected from the wellhead into the drill string assembly 114 at the inlet temperature and flows downwards to the bottom of the well. During this downward flow, it exchanges heat with the drilling fluid in the annulus and generates heat through viscosity dissipation as it flows within the drill pipe. After the drilling fluid flows out of the drill string assembly 114 into the annulus of the wellbore 116, it flows upward and exits from the drilling bell mouth 101. During its upward movement within the annulus, it transfers some heat to the drilling fluid inside the drill pipe and exchanges heat with the formation near the wellbore. At the same time, some heat is generated due to the friction of the drilling fluid flow.

[0008] Furthermore, the system parameters are as follows: mud pump 110 displacement 30L / s, drill string assembly 114 rotation speed 80RPM, drill string assembly 114 torque 10kN·m, drill string assembly 114 uses 139.7mm+127mm composite drill pipe, drilling fluid density 2.1g / cm³. 3 Drilling fluid inlet temperature 30℃, two-dimensional wellbore trajectory.

[0009] A method for controlling drilling temperature in long horizontal wells for high-temperature shale gas includes the following steps:

[0010] Step 1: Obtain the well's vertical depth, inclination depth, wellbore trajectory, machine speed, displacement, drilling fluid density, drilling fluid rheological parameters, drilling fluid thermophysical parameters, geothermal gradient, formation thermophysical parameters, and wellbore structural parameters.

[0011] Step 2: Wells where the predicted maximum circulating temperature of the drilling fluid at the bottom of the well exceeds 135°C should be equipped with surface cooling equipment.

[0012] Step 3: During the drilling process, a segmented circulation mode is adopted. When the well section with a static temperature of 125℃ is drilled down, the wellbore must be circulated for more than 15 minutes. In subsequent drilling operations, circulation is carried out once every 5 drill strings, and each circulation time is more than 15 minutes. When the temperature is still higher than 125℃ after the circulation, the pump is continuously started to drill down to the bottom of the subsequent well section.

[0013] Step 4: Before drilling down to the horizontal section, the drilling team should ensure that the mud pump and surface manifold are ready for use at any time, and the surface cooling device service provider should ensure that the surface cooling device is used continuously and synchronously during the high-temperature drilling cycle.

[0014] Step 5: When drilling in the horizontal section, if the bottom hole circulating temperature exceeds 135℃ and reaches the warning temperature of the rotary guide tool, the drill string should be kept within one column range, and the drill string assembly speed should be controlled at 30-60 RPM to circulate and cool down using the drilling flow rate. Drilling can only be resumed when the temperature stabilizes and drops to 135℃ or meets the requirements of the rotary guide tool.

[0015] Step 6: When connecting the drill string, stop the pump late and start it early to minimize downtime. After connecting the drill string, start the pump to the drilling flow rate before rotating the top drive. It is strictly forbidden to rotate the drill string when the pump is stopped. When encountering maintenance work such as pipe flushing or other maintenance operations, the construction team should establish continuous downhole circulation to continuously reduce the downhole temperature.

[0016] Step 7: Calculate the drilling fluid circulation temperature in the drill string assembly 114, the drilling fluid circulation temperature in the annulus, and the drilling fluid temperature entering the well using the following formulas.

[0017] Drilling fluid heat transfer model in drill string assembly 114

[0018]

[0019] Drill pipe wall heat transfer model

[0020]

[0021] Annular drilling fluid heat transfer model

[0022]

[0023] Formation, cementing sheath, and casing heat transfer model

[0024]

[0025] In the formula, Q p Heat generated by internal friction of drill string assembly 114, W / m; The drilling fluid density within drill string assembly 114 is given in kg / m³. 3 q represents the volumetric flow rate of the drilling fluid, in meters. 3 / s;C p The specific heat capacity of the drilling fluid. );T p Temperature of the drilling fluid inside drill string assembly 114, in °C; T w The wall temperature for the drill string assembly is 114 °C; T a Temperature of the drilling fluid in the annulus, in °C; T f Near-wellbore formation temperature, °C; T represents the formation, cementing sheath, and casing temperatures, °C; z represents depth, m; r p The inner radius of drill string assembly 114 is in meters (m); r a The outer radius of the drill string assembly is 114, in meters (m); r o r is the wellbore radius, in meters; r is the radial distance from the wellbore center, in meters; h p The convective heat transfer coefficient of the inner wall of the drill string assembly (114) is given by the following formula: );h a The convective heat transfer coefficient within the annulus, ); t is time, s.

[0026] Step 8: Based on the drilling fluid circulation temperature in the drill string assembly 114 and the drilling fluid circulation temperature in the annulus obtained above, optimize the drilling fluid density, drilling parameters such as rotation speed, displacement, and drill string assembly 114 to obtain the subsequent drilling fluid bottom hole circulation temperature. The drilling fluid returning to the wellhead continues to participate in the next stage of circulation cooling.

[0027] In step 3, a drilling mud pump with a displacement of 110 is used to circulate the drilling mud using a drill string assembly with a ground rotation speed of 30-80 RPM.

[0028] The beneficial effects of the embodiments of the present invention are:

[0029] (1) The present invention makes full use of the ground cooling device and adopts the method of injecting cooling drilling fluid into the well to directly and continuously circulate and cool the high temperature drilling fluid in the well;

[0030] (2) This invention fully utilizes the basic principles of heat transfer. By optimizing the drilling fluid density and drilling process parameters, the drilling fluid is maintained within the normal operating temperature range of downhole tools. This effectively prevents abnormal signals from rotary steerable tools, extends the service life of rotary steerable tools, reduces tripping time and the number of drill string changes, and improves drilling efficiency in horizontal sections. No additional equipment is required, and it has almost no impact on drilling operations. At the same time, this method of curve fitting based on actual measurement data allows for model correction, and its quantitative calculation method can intuitively represent the bottom hole circulating temperature, which is more convincing than some theoretical prediction models of bottom hole circulating temperature.

[0031] (3) The temperature control method adopted in this invention, combined with the ground cooling device 118, has the characteristics of high thermal conductivity of the medium used and small space occupation, which reduces the power load of the ground cooling device. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the high-temperature shale gas long horizontal well drilling temperature control system of the present invention;

[0034] Figure 2 For high-temperature shale gas horizontal wellbore trajectory;

[0035] Figure 3 The effect of drilling fluid density on bottom hole circulation temperature in high-temperature shale gas horizontal wells;

[0036] Figure 4 The effect of discharge rate on bottom hole circulation temperature in high-temperature shale gas horizontal wells;

[0037] Figure 5 The effect of rotational speed on bottom hole circulating temperature in high-temperature shale gas horizontal wells;

[0038] Figure 6 The effect of drilling tool assemblies on bottom hole circulation temperature in high-temperature shale gas horizontal wells.

[0039] Figure 1In the middle, 101-drilling bell mouth, 102-elevated trench and connecting pipeline, 103-solids control equipment, 104-conical tank, 105-valve, 106-centrifugal pump, 107-vertical heat exchanger, 108-cooling tower, 109-upper cement slurry tank, 110-mud pump, 111-riseer, 112-hose, 113-top drive, 114-drill string assembly, 115-wellhead, 116-wellbore, 117-pipeline, 118-surface cooling device. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0041] Please refer to Figure 1 The first embodiment of the present invention provides a high-temperature shale gas long horizontal well drilling temperature control system. Figure 2 The wellbore trajectory in the diagram is used as the standard trajectory for calculation, and temperature is controlled according to steps 1-8 of the invention. Figure 1 This is a schematic flow chart of a continuous downhole cooling circulation system for high-temperature shale gas wells, with an average drilling speed of 5–9 m / h. Figure 3 The study investigated the changes in bottom hole drilling fluid circulation temperature in relation to drilling fluid density, horizontal section length, and vertical depth. The results showed that, with the target producing formation vertical depth at 3600m and all other relevant parameters remaining constant, the bottom hole drilling fluid circulation temperature did not exceed 125℃ when the drilling fluid density was 1.9g / cc and the horizontal section length increased from 0m to 2000m. Therefore, as long as the mechanical properties of the drill string assembly could meet the requirements of a single drilling run, a 2000m horizontal section could be completed in one run without requiring tripping operations due to high temperature causing the MWD / LWD module to fail. When the drilling fluid density is 2.3 g / cc and the horizontal section length is 2000 m, the bottom hole drilling fluid circulation temperature does not exceed 135℃. Therefore, as long as the temperature resistance of the drill string assembly does not exceed 135℃ and the mechanical properties can meet the requirements of one drilling trip, the horizontal section of 2000 m can be completed in one trip without the need for tripping or pulling out of the drill string due to high temperature causing the MWD / LWD module to fail. For some rotary steering tools with lower temperature resistance, appropriate circulation cooling can be performed for subsequent drilling operations.

[0042] Figures 4 to 6Sensitivity analysis results of relevant parameters such as drill string rotation speed 114 and mud pump displacement 110 were provided for the bottom hole circulating temperature during drilling. This provided a theoretical basis for temperature control methods and a selection of practical temperature control parameters. Parameters such as low rotation speed, medium displacement, appropriate inlet temperature, and large-diameter drill string assembly can achieve good bottom hole temperature control.

[0043] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A method for controlling drilling temperature in long horizontal wells for high-temperature shale gas, characterized in that, A high-temperature shale gas long horizontal well drilling temperature control system is adopted. The high-temperature shale gas long horizontal well drilling temperature control system includes a drill string assembly (114), a surface cooling device (118), a mud pump (110), a top drive (113), and a solids control device (103). The drill string assembly (114) is placed in the wellbore (116) and forms an annulus with the wellbore (116). The drilling fluid returning from the drilling bell mouth (101) enters the solids control device (103) along the overhead channel (102). After removing part of the solid phase content, it enters the conical tank (104) at the bottom of the solids control device (103) through the flow channel. The conical tank (104) and the vertical heat exchanger (107) are connected by valves (105), centrifugal pumps (106), and pipelines (107). 17) Connection: The drilling fluid enters the vertical heat exchanger (107) through the valve (105), centrifugal pump (106), and pipeline (117). After the first stage of cooling, the low-temperature drilling fluid returns to the upper cement slurry tank (109). Through the pipeline (117), the drilling fluid enters the mud pump (110), enters the hose (112) through the riser (111), and then enters the drill string assembly (114) through the top drive (113). After the drilling fluid circulates to the bottom of the well, it is circulated again through the wellbore (116) and the drilling bell mouth (101). The above process is repeated. The ground cooling device (118) consists of the valve (105), centrifugal pump (106), vertical heat exchanger (107), cooling tower (108), and pipeline (117). The method for controlling drilling temperature in long horizontal wells for high-temperature shale gas includes the following steps: Step 1: Obtain the well's vertical depth, inclination depth, wellbore trajectory, machine speed, displacement, drilling fluid density, drilling fluid rheological parameters, drilling fluid thermophysical parameters, geothermal gradient, formation thermophysical parameters, and wellbore structural parameters. Step 2: When the predicted maximum circulating temperature of the drilling fluid at the bottom of the well exceeds 135°C, the well should be equipped with a surface cooling device. Step 3: During the drilling process, a segmented circulation mode is adopted. When the well section with a static temperature of 125℃ is drilled down, the wellbore must be circulated for more than 15 minutes. In subsequent drilling operations, circulation is carried out once every 5 drill strings, and each circulation time is more than 15 minutes. When the well section is drilled down to a section where the temperature is still higher than 125℃ after circulation, the pump is continuously turned on and the subsequent well sections are drilled to the bottom. Step 4: Before drilling down to the horizontal section, the drilling team should ensure that the mud pump (110) and the surface pipeline (117) are ready for use at any time, and the service provider of the surface cooling device (118) should ensure that the surface cooling device (118) is used continuously and synchronously during the high-temperature drilling cycle. Step 5: When drilling in the horizontal section, if the bottom hole circulation temperature exceeds 135℃ and reaches the warning temperature of the drill string assembly (114) rotary guide tool, the drill string should be kept within one column range, and the top drive speed should be controlled to circulate and cool down using the drilling flow rate. Drilling can only be resumed when the temperature stabilizes and drops to 135℃ or meets the requirements of the rotary guide tool. Step 6: When connecting the drill string, stop the pump late and start the pump early to minimize downtime. After connecting the drill string, start the pump to the drilling flow rate before rotating the top drive. It is strictly forbidden to rotate the drill string when the pump is stopped. When encountering maintenance work such as pipe flushing or other maintenance operations, the construction team should establish continuous downhole circulation to continuously reduce the downhole temperature. Step 7: Calculate the drilling fluid circulation temperature in the drill string assembly (114), the drilling fluid circulation temperature in the annulus, and the drilling fluid temperature entering the well using the following formulas. The internal temperature control equation of the drill string assembly (114) is as follows: Drilling fluid heat transfer model within drill string assembly (114): ； Heat transfer model of the drill string assembly (114) wall: ； Annular drilling fluid heat transfer model ； Formation, cementing sheath, and casing heat transfer model ； In the formula, Q p Heat generated by internal friction of the drill string assembly (114), W / m; The drilling fluid density within the drill string assembly (114) is kg / m³. 3 q represents the volumetric flow rate of the drilling fluid, in meters. 3 / s;C p The specific heat capacity of the drilling fluid. ;T p The drilling fluid temperature inside the drill string assembly (114), in °C; T w The wall temperature of the drill string assembly (114) is ℃; T a Temperature of the drilling fluid in the annulus, in °C; T f Near-wellbore formation temperature, °C; T represents the formation, cementing sheath, and casing temperatures, °C; z represents depth, m; r p r is the inner radius of the drill string assembly (114), in meters. a The outer radius of the drill string assembly (114) is m; r o r is the radius of the wellbore (116), in meters; r is the radial distance from the center of the wellbore (116), in meters; h p The convective heat transfer coefficient of the inner wall of the drill string assembly (114) is given by the following formula: h a The convective heat transfer coefficient within the annulus of wellbore (116) is given. t represents time, in seconds; Step 8: Based on the drilling fluid circulation temperature in the drill string assembly (114) and the drilling fluid circulation temperature in the annulus of the wellbore (116) obtained in Step 7, the drilling fluid density, the rotation speed of the drill string assembly (114) and the discharge of the mud pump (110) in the drilling parameters are optimized to obtain the subsequent bottom hole circulation temperature of the drilling fluid. The drilling fluid returning from the drilling horn (101) continues to participate in the next stage of circulation cooling.

2. The high-temperature shale gas long horizontal well drilling temperature control method according to claim 1, characterized in that, The system parameters are as follows: mud pump (110), displacement 30L / s, drill string assembly (114) speed 80rpm, drill string assembly (114) torque 10kN·m, drill string assembly (114) adopts a 139.7mm+127mm composite, drilling fluid density 2.1g / cm³. 3 The drilling fluid temperature at the drill string assembly (114) is 30℃.

3. The high-temperature shale gas long horizontal well drilling temperature control method according to claim 1, characterized in that, In step 3, the mud pump (110) circulates the mud using the drilling discharge rate.

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