Rock core tensile strength testing device and method under confining pressure based on Brazilian splitting

Abstract

The invention discloses a rock core tensile strength testing device and method under confining pressure conditions based on Brazilian splitting, comprising a cylinder, the upper and lower ends of the cylinder are respectively connected with an upper indenter and a lower indenter; a guide cylinder is arranged in the cylinder , the rubber sleeve, and the pressure rod passing through the upper pressure head and the guide cylinder, the support rod passing through the lower pressure head, the bottom end of the pressure rod and the top end of the support rod are all inserted into the rubber sleeve; the bottom surface of the guide cylinder, the support rod The top surface is an arc surface matching the outer diameter of the rock core to be tested. When the pressure rod goes down to the bottom end of the stroke, the enlarged diameter part on the pressure rod contacts the top of the guide cylinder; the bottom of the pressure rod is provided with a splitting cutter head; A closed annular space is formed between the sleeve and the cylinder, and a confining pressure inlet is opened on the cylinder. The invention is used to solve the inability to apply confining pressure to the rock core to simulate the geological environment in the development of oil and gas in the prior art, and the difficulty in satisfying the accurate positioning of the small-volume rock core, which leads to the lack of accuracy of the experimental results, so as to realize the ability to carry out small-volume rock core Accurate positioning while facilitating the purpose of applying confining pressure.

Description

technical field

[0001] The invention relates to the field of petroleum and natural gas, in particular to a device and method for testing rock core tensile strength under confining pressure conditions based on Brazilian splitting. Background technique

[0002] In the field of oil and gas, the tensile strength of formation rock is an important geological parameter, which is closely related to the wellbore stability during drilling and hydraulic fracturing during stimulation. Tensile strength is a basic concept in rock mechanics courses, an important mechanical property of rocks, and an important parameter in the stability analysis of rock structures. As a typical brittle material, the tensile strength of rock is much smaller than its compressive strength. When the tensile stress on the rock is higher than the tensile strength of the rock, the rock will undergo tensile failure, and its failure is usually controlled by the tensile strength. Therefore, the rock Accurate measurem...

Examples

Embodiment 1

[0053] Such as Figure 2 to Figure 3 , Figure 6 to Figure 7 The shown rock core tensile strength test device under the confining pressure condition based on Brazil splitting, wherein figure 2 and image 3 It is a schematic diagram of the same structure in different sections; it includes a cylinder body 1, and the upper and lower ends of the cylinder body 1 are respectively detachably connected to the upper pressure head 2 and the lower pressure head 3; the cylinder body 1 is provided with a guide cylinder 6 and a rubber sleeve 7, It also includes a pressing rod 4 passing through the upper pressing head 2 and the guide cylinder 6 in the axial direction, and a support rod 5 passing through the lower pressing head 3 in the axial direction. The pressing rod 4 is slidingly fitted with the upper pressing head 2 and the guiding cylinder 6, The supporting rod 5 is detachably fixedly connected with the lower pressing head 3, and the bottom end of the pressing rod 4 and the top end ...

Embodiment 2

[0069] Such as Figure 4 to Figure 7 The shown rock core tensile strength test device under the confining pressure condition based on Brazil splitting, wherein Figure 4 and Figure 5 It is a schematic diagram of the same structure in different sections; the difference between this embodiment and Embodiment 1 is that it also includes an annular piston 14 outside the pressure rod 4, the outer wall of the annular piston 14 is in contact with the inner wall of the upper pressing head 2, and the annular piston 14 is in contact with the pressure rod. 4 is relatively fixed in the axial direction; it also includes a piston fluid inlet 15 provided on the barrel 1 and / or the upper pressure head 2, and the fluid applied to the piston fluid inlet 15 pushes the annular piston 14 downward. The top of the pressure rod 4 is sleeved with a hollow tightening bolt 16. The pressure rod 4 includes a diameter-expanding portion 401. The tightening bolt 16 is located above the diameter-expanding po...

technical field

[0001] The invention relates to the field of petroleum and natural gas, in particular to a device and method for testing rock core tensile strength under confining pressure conditions based on Brazilian splitting. Background technique

[0002] In the field of oil and gas, the tensile strength of formation rock is an important geological parameter, which is closely related to the wellbore stability during drilling and hydraulic fracturing during stimulation. Tensile strength is a basic concept in rock mechanics courses, an important mechanical property of rocks, and an important parameter in the stability analysis of rock structures. As a typical brittle material, the tensile strength of rock is much smaller than its compressive strength. When the tensile stress on the rock is higher than the tensile strength of the rock, the rock will undergo tensile failure, and its failure is usually controlled by the tensile strength. Therefore, the rock Accurate measurem...

Examples

Embodiment 1

[0053] Such as Figure 2 to Figure 3 , Figure 6 to Figure 7 The shown rock core tensile strength test device under the confining pressure condition based on Brazil splitting, wherein figure 2 and image 3 It is a schematic diagram of the same structure in different sections; it includes a cylinder body 1, and the upper and lower ends of the cylinder body 1 are respectively detachably connected to the upper pressure head 2 and the lower pressure head 3; the cylinder body 1 is provided with a guide cylinder 6 and a rubber sleeve 7, It also includes a pressing rod 4 passing through the upper pressing head 2 and the guide cylinder 6 in the axial direction, and a support rod 5 passing through the lower pressing head 3 in the axial direction. The pressing rod 4 is slidingly fitted with the upper pressing head 2 and the guiding cylinder 6, The supporting rod 5 is detachably fixedly connected with the lower pressing head 3, and the bottom end of the pressing rod 4 and the top end ...

Embodiment 2

[0069] Such as Figure 4 to Figure 7 The shown rock core tensile strength test device under the confining pressure condition based on Brazil splitting, wherein Figure 4 and Figure 5 It is a schematic diagram of the same structure in different sections; the difference between this embodiment and Embodiment 1 is that it also includes an annular piston 14 outside the pressure rod 4, the outer wall of the annular piston 14 is in contact with the inner wall of the upper pressing head 2, and the annular piston 14 is in contact with the pressure rod. 4 is relatively fixed in the axial direction; it also includes a piston fluid inlet 15 provided on the barrel 1 and / or the upper pressure head 2, and the fluid applied to the piston fluid inlet 15 pushes the annular piston 14 downward. The top of the pressure rod 4 is sleeved with a hollow tightening bolt 16. The pressure rod 4 includes a diameter-expanding portion 401. The tightening bolt 16 is located above the diameter-expanding po...

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