A method for predicting anchoring performance of a ground anchor under thermal cycling conditions for a heavy oil thermal recovery well

Abstract

The present application relates to the technical field of oil exploitation, in particular to a method for predicting anchoring performance of a ground anchor under thermal cycle condition of a heavy oil thermal recovery well. The method comprises the following steps: concentrically and staggeredly arranging an inner casing and an outer casing, and arranging a ground anchor at the end of the inner casing in the outer casing; injecting a solidifying agent into the annulus between the inner casing and the outer casing, and waiting for condensation until the solidifying agent reaches the solidification condition, so as to prepare a sample of the inner casing, the outer casing and the ground anchor; clamping the two ends of the sample between the frames of a testing machine; winding an induction heating belt outside the outer casing; applying an axial force by the frame of the testing machine, and collecting the stress of the ground anchor by a force sensor. The present application is simple to operate and easy to implement, and is fast and convenient for detecting the performance and quality of the ground anchor. The present application has a wide range of applications and can fully meet the detection of different types of ground anchors.

Description

Technical Field

[0001] This invention relates to the field of petroleum extraction technology, specifically to a method for predicting the anchoring performance of ground anchors under thermal circulation conditions in heavy oil thermal recovery wells. Background Technology

[0002] Steam injection is currently the most common method for heavy oil thermal recovery both domestically and internationally. To avoid the enormous compressive stress generated by the expansion and elongation of the casing under high-temperature steam, which could lead to casing damage, oilfields commonly employ prestressed cementing to address this issue. Ground anchors are a unique cementing tool in prestressed cementing technology. The main function of ground anchors is to apply pre-tension to the casing string, securing the lower end of the casing string firmly to the wellbore. The ability of ground anchors to secure the casing string and their service life directly affect the safety of production. Once ground anchors fail, the casing may fail under pressure from high-temperature steam, compromising the integrity of the wellbore. Currently, there is no definitive laboratory testing method to determine the anchoring capacity of ground anchors, i.e., their performance and quality, and therefore, prediction is not possible. Summary of the Invention

[0003] This invention provides a method for predicting the anchoring performance of ground anchors under thermal circulation conditions in heavy oil thermal recovery wells. This method overcomes the problem that existing technologies cannot test the performance and quality of ground anchors, making it difficult to predict the failure of the casing under pressure from high-temperature steam, which in turn damages the integrity of the wellbore.

[0004] To achieve the objective of this invention, the technical solution is: a method for predicting the anchoring performance of ground anchors under thermal circulation conditions in heavy oil thermal recovery wells, comprising the following steps:

[0005] Step 1: Set the inner and outer sleeves concentrically and staggered, and place the ground anchor inside the outer sleeve and at the end of the inner sleeve.

[0006] Step 2: Inject curing agent into the annulus between the inner and outer sleeves, and wait for the curing agent to solidify. The inner sleeve, outer sleeve, and ground anchor are then used to prepare a sample.

[0007] Step 3: Clamp both ends of the sample between the frames of the testing machine;

[0008] Step 4: Wrap induction heating tape around the outside of the outer sleeve;

[0009] Step 5: An axial force is applied to the frame of the testing machine, and the force sensor collects the force on the ground anchor.

[0010] Furthermore, a connecting rod is provided between the outer sleeve and the testing machine frame. The connecting rod is coaxial with the outer sleeve, and the force sensor is mounted on the connecting rod.

[0011] Furthermore, the aforementioned connecting rod is a horizontally arranged T-shaped rod, with the head of the T-shaped rod positioned at the end of the outer sleeve.

[0012] Furthermore, the inner sleeve, outer sleeve, connecting rod, and frame are all connected by threads.

[0013] Furthermore, the aforementioned curing agent is cement.

[0014] Compared with the prior art, the advantages of the present invention are as follows:

[0015] (1) The method is simple to operate and easy to implement: The present invention uses the method of connecting the inner sleeve to the ground anchor + the outer sleeve to prepare the sample, which can realistically simulate the ground anchoring condition. At the same time, induction heating is used to heat the sleeve and the ground anchor sample, which can simulate the service environment of the ground anchor under thermal mining conditions to the greatest extent, predict the actual stress and performance of the ground anchor, and thus better guide the on-site process formulation and ground anchor selection.

[0016] (2) This method is quick and convenient for testing the performance and quality of ground anchors. By using a force sensor mounted on the connecting rod, the force sensor monitors the force on the sample under thermal cycling conditions. By judging the change in force value, the anchoring effect of the ground anchor can be quantitatively judged. At the same time, by improving the accuracy of the force sensor, the force change under small deformation can be tested, thereby improving the test accuracy.

[0017] (3) It has a wide range of applications and can fully meet the testing needs of different types of ground anchors. The inner and outer sleeves are fixed by filling with cement, which is close to the actual field conditions. According to the test requirements, the cement can be replaced with other fixing materials for testing. For example, different cement formulations can be selected for testing to compare the cement performance. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention;

[0019] Figure 2 for Figure 1 A partial sectional view of section A in the middle.

[0020] In the diagram: 1. Frame; 2. Ground anchor; 3. Inner sleeve; 4. Outer sleeve; 5. Hardener; 6. Connecting rod; 7. Force sensor; 8. Induction heating belt. Detailed Implementation

[0021] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0022] See Figure 1 A method for predicting the anchoring performance of ground anchors under thermal cycling conditions in heavy oil thermal recovery wells, specifically including the following steps:

[0023] Step 1: The inner sleeve 3 and the outer sleeve 4 are concentrically offset. The ground anchor 2 is set inside the outer sleeve 4 and at the end of the inner sleeve 3. The position is determined by auxiliary devices such as centering mechanism and bracket.

[0024] Step 2: Inject curing agent 5 into the annulus between the inner casing 3 and the outer casing 4, and allow it to solidify until it reaches the required setting time. In this embodiment, the curing agent 5 is cement. The mixing ratio and setting time can be strictly determined according to the cement used in the oil well, depending on the testing requirements. Generally, the setting time is 24 hours. Considering that the downhole temperature is generally higher than the laboratory temperature, the setting time can be appropriately increased in this embodiment. The inner casing 3, outer casing 4, and ground anchor 2 are fixedly connected as a single unit to prepare a sample.

[0025] Step 3: Place the two ends of the sample between the frame 1 of the testing machine. A connecting rod 6 is installed between the end of the outer sleeve 4 and the frame 1 of the testing machine. The connecting rod 6 is a transversely arranged T-shape, with the head of the T-shape resting on the end of the outer sleeve 4, providing a large contact area and ensuring uniform force distribution. The connecting rod 6 is coaxially arranged with the outer sleeve 4, and the end of the inner sleeve 3 is connected to the frame 1. All connection forces are achieved through threads. See [link to relevant documentation]. Figure 2 This ensures both connection strength and sealing. The sensor 7 is mounted on the connecting rod 6.

[0026] In this invention, any testing machine that can apply pressure to both ends of the pipe can be used, such as a composite loading testing machine used for full-size physical testing of oil casing pipes;

[0027] Step 4: Wrap an induction heating belt 8 around the outside of the outer casing 4. The induction heating belt 8 simulates the actual stress conditions of the ground anchor under steam injection and steam drive conditions in heavy oil thermal recovery wells, thereby testing its anchoring capacity under thermal cycling conditions.

[0028] Step 5: The frame 1 of the testing machine applies an axial force inward to keep the sample from displaced during the test. Under thermal cycling conditions, the force sensor 7 collects the force on the ground anchor 2, thereby determining the anchoring performance of the ground anchor 2 under thermal cycling conditions.

[0029] Force sensor 7 is used to monitor the force on the sample under thermal cycling conditions. If the force value suddenly decreases, it can be considered that the ground anchor 2 has failed to anchor.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. All equivalent structural changes made based on the description and drawings of the present invention should be included within the scope of patent protection of the invention.

Claims

1. A method for predicting the anchoring performance of ground anchors under thermal cycling conditions in heavy oil thermal recovery wells, characterized in that: Includes the following steps: Step 1: Set the inner sleeve (3) and the outer sleeve (4) concentrically and staggered, and set the ground anchor (2) inside the outer sleeve (4) and at the end of the inner sleeve (3); Step 2: Inject curing agent (5) into the annulus between the inner sleeve (3) and the outer sleeve (4), and wait for the curing agent (5) to solidify. The inner sleeve (3), the outer sleeve (4) and the ground anchor (2) are then prepared as a sample. Step 3: Clamp both ends of the sample between the frame (1) of the testing machine; Step 4: Wrap an induction heating tape (8) around the outside of the outer sleeve (4); Step 5: Apply axial force to the frame (1) of the testing machine, and the force sensor (7) collects the force on the ground anchor (2).

2. The method for predicting the anchoring performance of ground anchors under thermal cycling conditions in heavy oil thermal recovery wells according to claim 1, characterized in that: A connecting rod (6) is provided between the outer sleeve (4) and the frame (1) of the testing machine. The connecting rod (6) is coaxial with the outer sleeve (4), and the force sensor (7) is provided on the connecting rod (6).

3. The method for predicting the anchoring performance of ground anchors under thermal cycling conditions in heavy oil thermal recovery wells according to claim 2, characterized in that: The connecting rod (6) is a T-shaped rod arranged horizontally, with the head of the T-shaped rod positioned at the end of the outer sleeve (4).

4. The method for predicting the anchoring performance of ground anchors under thermal cycling conditions for heavy oil thermal recovery wells according to claim 3, characterized in that: The inner sleeve (3), outer sleeve (4), connecting rod (6) and frame (1) are all connected by threads.

5. The method for predicting the anchoring performance of ground anchors under thermal cycling conditions in heavy oil thermal recovery wells according to claim 4, characterized in that: The curing agent (5) is cement.

Images