Fine sand plugging thick liquid annular space anti-injection anti-extrusion plugging method

Abstract

The invention provides a fine sand plugging thick liquid annular space inverted-injection inverted-extrusion plugging method. The method has high adaptability in different leakage channels, and matching ability of a leak agent to the leakage channels is improved, and the leak agent can squeeze into different leakage channels; fine sand in the plugging thick liquid is easy to pile up in a crack, after extrusion sealing, a high strength plugging wall is formed, and loss circulation reappearing is not prone to happen. Inverted-injection inverted-extrusion is conducted from the annular space, motion range of the plugging thick liquid is reduced due to the existence of down-hole drilling tools, and the plugging thick liquid is obliged to enter a leakage layer easier. The annular space inverted-injection inverted-extrusion is more suitable for the characteristic of gravity sinking of the high density fine sand plugging thick liquid, the thick liquid body can enter the leakage layer freely in the process of sinking, and more plugging thick liquid bodies are obliged to enter the leakage layer through well shut-in extrusion.

Description

technical field [0001] The invention belongs to the technical field of petroleum drilling, and in particular relates to a method for back-injection and back-extrusion of fine sand plugging slurry in an annular space. Background technique [0002] The buried depth of the Jurassic Luohe Formation in Changqing Xifeng Oilfield is 700-1100m, and the vertical and horizontal fractures are well developed. The pressure-bearing plugging effect of some leaking wells is not ideal. Through the water hole of the drilling tool or deposited to the bottom of the well, it cannot effectively enter the leakage layer, and the squeeze pressure cannot directly reflect the annular pressure. [0003] 1. There are many lost layers in some lost wells, and it is difficult to accurately determine the location [0004] Some lost wells have multiple losses, and the location of the loss is difficult to determine, so it is difficult to determine the depth of the drilling tool. It often occurs that the dril...

AI Technical Summary

Problems solved by technology

[0002] The buried depth of the Jurassic Luohe Formation in Changqing Xifeng Oilfield is 700-1100m, and the vertical and horizontal fractures are well developed. The pressure-bearing plugging effect of some leaking wells is not ideal. Through the water hole of the drilling tool or deposited to the bottom of the well, it cannot effectively enter the leakage layer, and the squeeze pressure cannot directly reflect the annular pressure

[0003] 1. There are many lost layers in some lost wells, and it is difficult to accurately determine the location

[0004] Some lost wells have multiple losses, and the location of the loss is difficult to determine, so it is difficult to determine the depth of the drilling tool. It often occurs that the drilling tool penetrates the leakage layer and then is squeezed, and then the plugging agent settles at the bottom of the well; or the drilling tool is above the leakage layer. If the distance is too far, a plug section will be formed in the wellbore after being squeezed, and the plugging slurry will not be able to enter the leaking layer, resulting in the illusion of high pressure

[0005] 2. The existing conventional plugging agent has weak pressure bearing capacity

[0006] The currently used plugging materials include fiber-based bridging plugging agents, solidified cement plugging agents, apricot hook and other coarse-grained plugging agents, and the common determination of the existence of these plugging agents is that they are weak in strength and easy to be affected by external forces. after deformed or broken

[0007] 3. There are defects in the plugging method of positive injection and positive extrusion

[0008] Positive injection and positive extrusion plugging methods generally use the drilling tool to go down to the position above the leaky layer. In this way, due to the large volume of the wellbore during the sealing process, the plugging slurry has a wide range of activities. The utilization rate of leakage agent is low, resulting in poor effect of extrusion sealing