A friction coefficient measuring slot for lowering a variable diameter horizontal well string

Abstract

The present invention relates to a friction coefficient measuring trough for a horizontal well string with a variable diameter. The trough is composed of a test trough body and a radial telescopic mechanism. The test trough body is a metal trough body with an upper opening, and various well fluids can be filled inside. The radial telescopic mechanism can manually drive the racks arranged radially around the axis of the simulated wellbore to move radially, thereby simulating wellbores of different sizes. A large number of standard artificial cores are installed on the core group beam frame, and the height of each core extending out of the blind hole can be set separately. The upper end of the core can be smeared with a mud cake mixed with rock cuttings to simulate an irregular well wall. It can fully reflect the influence of complex factors such as the actual wellbore state, downhole tool structure and well fluid composition on the friction coefficient, and thus put forward reasonable suggestions and requirements for the design of drilling and completion plans and construction operations.

Description

Technical Field

[0001] The invention relates to a test for detecting a friction coefficient of a pipe string during drilling and completion of a horizontal well in the petroleum field, and in particular to a friction coefficient measuring groove for a horizontal well pipe string with a variable diameter. Background Art

[0002] During extended-reach horizontal well drilling and completion operations, the frictional resistance between the tubing and the wellbore wall is a key factor influencing whether the drill string can generate sufficient weight on bit and whether the casing can be successfully lowered. Therefore, prior to construction, it is necessary to use numerical models to predict the frictional resistance and hook load during the entire tubing lowering process. In this prediction process, the friction coefficient is a key parameter, directly related to the accuracy of the calculation results. Typically, the friction coefficient is taken as an empirical value, or the hook load curve measured in adjacent wells is substituted into the model for inversion. However, empirical values ​​often fail to reflect the actual operating conditions of the current well location, and the inversion results depend on the rationality of the model and are often unavailable due to a lack of relevant data from adjacent wells.

[0003] To address these issues, experts and scholars have used experimental methods to determine the friction coefficient. Patents 201510740610.X, 201610860503.5, and 201710059756.7 relate to a surface friction coefficient testing device. A test head applies positive pressure to a sample and measures the torque driving the sample's rotation, thereby calculating the friction coefficient. It's worth noting that these patents all test the material itself, which should strictly be referred to as the "friction coefficient," determined by the properties of the tubing string and the rock.

[0004] During the actual construction process, the frictional resistance of the pipe string during running includes many complex factors, including: the presence of expansion, contraction and wellbore wall keyways due to the irregularity of the actual wellbore; the formation of sand bridges and cuttings beds due to unclean wellbore, which makes it difficult to pass through parts with larger outer diameters such as couplings and stabilizers on the pipe string, thereby generating "additional resistance"; different materials are used in different parts of the pipe string, such as the rubber barrel and metal jacket of the external pipe packer, resulting in complex and variable friction coefficients; drilling fluid and the mud cake formed by it usually have lubricating properties, which can reduce the frictional resistance of the pipe string during running to a certain extent; if a roller centralizer is used, the frictional resistance of the pipe string during running can also be reduced.

[0005] Therefore, the "friction coefficient" should be used to comprehensively characterize the complex friction characteristics mentioned above. Generally, the friction coefficient is greater than the friction coefficient. However, if the friction coefficient is to be tested, existing measurement devices cannot meet the requirements, and a new device that can reflect the complex working conditions of the well is needed. Summary of the Invention

[0006] Aiming at the deficiencies in the prior art, the present invention provides a friction coefficient measuring groove for lowering a horizontal well pipe string with a variable diameter.

[0007] The technical solution is as follows:

[0008] A friction coefficient measuring slot for a horizontal well pipe string with a variable diameter is provided, comprising a test slot, a radial expansion mechanism, and a core group beam frame;

[0009] The experimental tank is a tank body with an upper opening. A partition is provided inside to divide the tank body into a mechanism tank and a working tank. A sliding sleeve is processed on the left side plate of the tank body. A set of radial telescopic mechanisms set opposite to each other are provided on the partition and the bottom plate of the tank body respectively. A core group beam frame is set between the two sets of radial telescopic mechanisms.

[0010] Furthermore, the radial telescopic mechanism is composed of a plurality of gear rack pairs, and the gear rack pairs are sequentially connected by universal joints to form a semi-annular array.

[0011] Furthermore, the gear rack pair includes a variable diameter rack, a variable diameter gear, and a gear bracket;

[0012] The gear brackets are fixed in pairs on the experimental tank, with shaft holes on the top and L-shaped opening slots on the bottom;

[0013] The reducing gear is rotatably mounted on the reducing rack through the gear bracket;

[0014] Both sides of the bottom of the reducing rack are provided with convex rails, which are slidably matched with the L-shaped opening grooves.

[0015] Furthermore, convex shafts are provided at both ends of the variable diameter gear, and the convex shafts are rotatably matched with the shaft holes on the gear bracket and pass through the shaft holes on the gear bracket;

[0016] A plurality of gear rack pairs are formed into a radial semi-annular array around the axis to form a radial telescopic mechanism. Between each two adjacent gear rack pairs, the convex shafts of the variable diameter gears are sequentially connected through universal joints.

[0017] Furthermore, it also includes a rotating rod bracket and a variable diameter rotating rod, and rectangular holes are provided on the variable diameter gears at both ends of the radial telescopic mechanism;

[0018] A rotating rod bracket is provided at both ends of the top of the working tank, and shaft holes are provided at both ends of the rotating rod bracket;

[0019] The reducing rod is inserted into the shaft hole of the rod bracket to form a rotational fit, and the rectangular mortise and tenon head of the reducing rod is inserted into the rectangular hole of the upper reducing gear.

[0020] Furthermore, the variable diameter rack is a straight rack structure, with convex rails processed at both ends and an arc plate processed at the top.

[0021] Furthermore, both ends of the core group beam frame are respectively connected to the partition plate and the arc-shaped plate on the bottom plate of the trough body.

[0022] Furthermore, both ends of the arc-shaped plate are processed into saw teeth.

[0023] Furthermore, the universal joint is composed of a cross shaft, a shaft fork and a rectangular shaft. The two rectangular shafts are hinged to the cross shaft through the shaft fork, and the rectangular shaft is connected to the convex shaft of the variable diameter gear.

[0024] Furthermore, the core assembly beam frame is a porous rod-shaped structure, one side of which is machined with a linear array of blind holes.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. Simulate actual wellbore conditions. A large number of standard artificial cores are densely installed on the core stack beam to simulate a horizontal continuous wellbore. The height of each core extending from the blind hole is appropriately adjusted to simulate irregular wellbores, including wellbore expansions, wellbore contractions, wellbore wall keyways, and minor wellbore fluctuations. A mud cake mixed with cuttings is applied to the top of the core to simulate an unclean wellbore. The radial expansion mechanism can be manually adjusted to simulate wellbore sizes. Analyzing the impact of these factors on the friction coefficient can provide reasonable recommendations for wellbore trajectory design and well washing and well dredging operations.

[0027] 2. Testing full-size tool samples. Downhole tools have varying dimensions and coating materials at different locations. This patent uses full-size samples for testing, fully considering the impact of these two factors on the friction coefficient and providing recommendations for downhole tool improvements.

[0028] 3. Liquid injection. The measurement tank can be filled with different types of liquids to simulate the effect of drilling fluid composition on the friction coefficient. If drilling fluid is injected and combined with a mud cake applied to the top of the core, the optimal drilling fluid formula can be studied to ensure good lubricity. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic structural diagram of an embodiment of the present invention

[0030] Figure 2 For press Figure 1 Schematic diagram of the gear rack pair structure shown

[0031] Figure 3 For press Figure 1 Schematic diagram of the experimental tank structure shown

[0032] Figure 4 For press Figure 1 Schematic diagram of the variable diameter rack structure shown

[0033] Figure 5 For press Figure 1 Schematic diagram of the variable diameter gear structure shown

[0034] Figure 6For press Figure 1 Schematic diagram of the gear bracket structure shown

[0035] Figure 7 For press Figure 1 Schematic diagram of the universal joint structure shown

[0036] Figure 8 For press Figure 1 Schematic diagram of the variable diameter rotating rod structure shown

[0037] Figure 9 For press Figure 1 Schematic diagram of the rotating rod bracket structure shown

[0038] Figure 10 For press Figure 1 Schematic diagram of the core group beam structure shown

[0039] Figure 11 For press Figure 1 Schematic diagram of the beam lock structure shown

[0040] Figure 12 For press Figure 1 Schematic diagram of the maximum circumference size of the gear rack pair radial telescopic mechanism shown

[0041] Figure 13 For press Figure 1 Schematic diagram of the maximum circle size of the core group beam array shown

[0042] Figure 14 For press Figure 1 Schematic diagram of the maximum simulated wellbore cross section with installed core shown

[0043] Figure 15 For press Figure 1 Schematic diagram of the minimum circumference size of the gear rack pair radial telescopic mechanism shown

[0044] Figure 16 For press Figure 1 Schematic diagram of the minimum circle size of the core group beam array shown

[0045] Figure 17 For press Figure 1 Schematic diagram of the minimum simulated wellbore cross section with core installed

[0046] In the figure: 1. Experimental trough, 2. Variable diameter rack, 3. Variable diameter gear, 4. Gear bracket, 5. Universal joint, 6. Variable diameter rotating rod, 7. Rotating rod bracket, 8. Core group beam frame, 9. Beam frame lock. DETAILED DESCRIPTION

[0047] like Figure 1As shown, a variable diameter horizontal wellbore test slot includes: a test slot 1, a variable diameter rack 2, a variable diameter gear 3, a gear bracket 4, a universal joint 5, a variable diameter rotating rod 6, a rotating rod bracket 7, a core group beam frame 8, and a beam frame lock 9.

[0048] like Figure 3 As shown, the experimental tank 1 is a metal tank body with an upper opening, and a partition 101 inside the tank body divides the tank body into two parts: a mechanism tank 102 and a working tank 103. The left side plate of the tank body is processed with a sliding sleeve 104, and the partition 101 is processed with a long elliptical through hole 105 and a semi-circular array of through holes 106 around the axis of the wellbore. The bottom plate 107 of the tank body is processed with a semi-circular array of through holes 108 around the axis of the wellbore.

[0049] like Figure 2 As shown, the variable diameter rack 2 is composed of teeth 21, a convex rail 22, and an arc plate 24. The convex rail 22 is arranged on both sides of the bottom of the rack 2, and the arc plate 24 is arranged at one end of the rack 2. Saw teeth 23 are processed on both sides of the arc plate 24.

[0050] like Figure 5 As shown, convex shafts 31 are processed at both ends of the variable diameter gear 3, and a rectangular through hole 32 is processed at the axis center of the convex shaft 31.

[0051] like Figure 6 As shown, the gear bracket 4 is an L-shaped bracket structure, with a sliding shaft hole 41 processed on the upper part, a through hole 42 processed on the bottom plate, and an open groove 43 processed on the bottom of the bottom plate.

[0052] like Figure 2 As shown, the teeth 21 of the reducing rack 2 are meshed with the reducing gear 3, the convex shafts 31 at both ends of the reducing gear 3 are respectively sleeved with the shaft holes 41 of the left and right gear brackets 4 and are rotationally matched, and the convex rails 22 at both ends of the reducing rack 2 are respectively embedded in the L-shaped opening grooves 43 of the left and right gear brackets 4 and are slidingly matched. A reducing rack 2, a reducing gear 3 and two gear brackets 4 constitute a gear rack pair.

[0053] like Figure 7 As shown, the universal joint 5 is composed of a cross shaft 51 , a shaft fork 52 and a rectangular shaft 53 .

[0054] like Figure 12As shown, the rack and pinion pair is fastened to one side of the working groove 103 through the through hole 42 of the gear bracket 4 and the through hole 106 of the partition 101 with bolts, and several (7 in this case) rack and pinion pairs are formed around the axis to form a radial semi-annular array radial telescopic mechanism A; another group of rack and pinion pairs is fastened to the through hole 108 of the groove body bottom plate 107 through the through hole 42 of the gear bracket 4 with bolts, and several (7 in this case) rack and pinion pairs are formed around the axis to form a radial semi-annular array radial telescopic mechanism B. In these two semi-annular rack and pinion arrays, between each adjacent two rack and pinion pairs, the rectangular shafts 53 at both ends of the universal joint 5 are respectively inserted into the rectangular holes 32 of the adjacent variable-diameter gears 3 for series connection, so that the variable-diameter gears 3 in the array are linked.

[0055] like Figure 8 As shown, the diameter-reducing rotating rod 6 is a rotating body with an inner hexagonal blind hole 61 on the top and a rectangular mortise and tenon head 62 on the bottom.

[0056] like Figure 9 As shown, the rotating rod bracket 7 is a long plate structure (see Figure 9 ), with both ends bent, and sliding bearing holes 71 processed on the slats.

[0057] The two rotating rod brackets 7 are respectively installed at the top two ends of the experimental tank 1 by welding. The reducing rotating rod 6 is inserted into the axial hole 71 of the rotating rod bracket 7 in a sliding fit, and its rectangular mortise and tenon head 62 is inserted into the rectangular hole 32 of the reducing gear 3 of the uppermost gear rack pair (4 in this case).

[0058] like Figure 10 As shown, the core assembly beam 8 is a long, porous trapezoidal rod-like structure with side surfaces at both ends forming an angle n°. The bottom is processed into an arc surface 83, one end is processed with a groove 82, and the top is processed with a linear array of blind holes 81. The inner diameter φ and height H parameters of the blind holes 81 are equivalent to the standard core size used in the test.

[0059] like Figure 11 As shown, the beam lock head 9 is an L-shaped structure, with a threaded hole 91 processed on the upper part and a wedge block 92 processed on the lower part.

[0060] One end of the core group beam 8 is supported on the arc plate 24 of the deformed rack 2 of the semi-annular array A of the partition 101, and the other end is supported on the arc plate 24 of the deformed rack 2 of the semi-annular array B of the trough bottom plate 107. Several beams (13 in this case) are arranged in this way, and the wedge blocks 92 of the two beam lock heads 9 are respectively inserted into the open grooves 82 of the uppermost core group beams 8a and 8b.

[0061] The object of the present invention is to achieve:

[0062] Insert an ordinary hexagonal wrench into the inner hexagonal hole 61 of the reducing rod 6 to drive the reducing rod 6 to rotate the reducing gear 3. The engagement of the reducing rack 2 with the reducing gear 3 forces it to move toward the axis. Since the semi-annular array of the rack and pinion pair is connected in series by the universal joint 5, all the reducing gears 3 in the array rotate synchronously, that is, the reducing racks 2 in all the arrays also move synchronously toward the axis. The array circle shrinks radially. When the circle size reaches the requirement, the rotation stops. Place the core group beam frame 8 in sequence close to the arc plates 24 of all the reducing racks 2 in the semi-annular array of the rack and pinion pair, and finally lock all the core group beam frames 8 with the beam frame lock 9.

[0063] By placing a standard artificial core 10 in each blind hole 81 of each core group beam 8, the purpose of simulating a horizontal wellbore that meets the test conditions can be achieved.

[0064] The present invention consists of a test trough and a radial telescopic mechanism. The test trough is a metal trough with an upper opening, which can be filled with clean water, high-mineralization liquid, crude oil, oil-water mixture or mud, etc. to simulate the liquid environment of the wellbore. The radial telescopic mechanism can manually rotate the gear to drive the racks arranged radially around the axis of the simulated wellbore to move radially, thereby changing the radial size of the circle to simulate wellbores of different sizes. A large number of standard artificial cores are installed in the linear array of blind holes of the core group beam frame. The height of each core extending out of the blind hole can be set separately, and the upper end of the core can be smeared with mud cake mixed with rock chips to simulate irregular well walls. Since friction resistance basically does not involve the upper half of the wellbore, the present invention only includes the lower half of the wellbore structure.

Claims

1. A variable diameter horizontal well string is lowered into a friction coefficient measurement tank, characterized in that: It includes an experimental tank, a radial telescopic mechanism, and a core group beam frame; the experimental tank is a tank body with an upper opening, and a partition is provided inside to divide the tank body into a mechanism tank and a working tank. The left side plate of the tank body is processed with a sliding shaft sleeve, and a group of radial telescopic mechanisms set opposite to each other are provided on the partition and the bottom plate of the tank body respectively, and a core group beam frame is set between the two groups of radial telescopic mechanisms; the radial telescopic mechanism is composed of a number of gear rack pairs, and the gear rack pairs are connected in sequence by universal joints to form a semi-annular array; the gear rack pair includes a reducing rack, a reducing gear, and a gear bracket; the gear bracket They are fixed in pairs on the experimental trough, with an axial hole on the top and an L-shaped open groove on the bottom; the reducing gear is rotatably mounted on the reducing rack through a gear bracket; convex rails are provided on both sides of the bottom of the reducing rack, and the convex rails slide in conjunction with the L-shaped open groove; it also includes a rotating rod bracket and a reducing rotating rod, and rectangular holes are provided on the reducing gears at both ends of the radial telescopic mechanism; a rotating rod bracket is provided at each end of the top of the working trough, and axial holes are provided at both ends of the rotating rod bracket; the reducing rotating rod is inserted into the axial hole of the rotating rod bracket for rotational engagement, and the rectangular mortise and tenon head of the reducing rotating rod is inserted into the rectangular hole of the reducing gear at the upper part.

2. The variable diameter horizontal well tubing string lowered into the friction coefficient measuring slot according to claim 1 is characterized in that: A convex shaft is provided at both ends of the variable diameter gear, which is rotatably matched with the shaft hole on the gear bracket and passes through the shaft hole on the gear bracket; a plurality of gear rack pairs form a radial semi-annular array around the axis to form a radial telescopic mechanism, and the convex shafts of the variable diameter gear are sequentially connected between each adjacent two gear rack pairs through a universal joint.

3. The variable diameter horizontal well tubing string lowered into the friction coefficient measuring slot according to claim 2 is characterized in that: The variable diameter rack is a straight rack structure with convex rails at both ends and an arc plate at the top.

4. The variable diameter horizontal well tubing string lowered into the friction coefficient measurement slot according to claim 3 is characterized in that: The two ends of the core group beam frame are respectively connected to the partition plate and the arc plate on the bottom plate of the trough body.

5. The variable diameter horizontal well tubing string lowered into the friction coefficient measurement slot according to claim 4 is characterized in that: Both ends of the curved plate are processed into serrations.

6. The variable diameter horizontal well tubing string lowered into the friction coefficient measurement slot according to claim 5, characterized in that: The universal joint consists of a cross shaft, a shaft fork and a rectangular shaft. The two rectangular shafts are hinged to the cross shaft through the shaft fork, and the rectangular shaft is connected to the convex shaft of the variable diameter gear.

7. The variable diameter horizontal well tubing string lowered into the friction coefficient measurement slot according to claim 6, characterized in that: The core group beam frame is a porous rod-shaped structure with a linear array of blind holes machined on one side.

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