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Control method and device for applying back pressure to annulus

An annulus and target position technology, applied in earthwork drilling, wellbore/well components, sealing/isolation, etc., can solve the problems of oil and gas wells such as lost circulation, high pressure, and large back pressure, and achieve the goal of reducing lost circulation Effect

Active Publication Date: 2021-09-28
PETROCHINA CO LTD
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Problems solved by technology

It can solve the problem that in the prior art, during the waiting period of cement slurry, the pressure control equipment in the early stage exerts too much back pressure on the annulus, causing the pressure in the annulus to be greater than the fracture pressure of the formation, resulting in the phenomenon of lost circulation in oil and gas wells problem, the technical solution is as follows:

Method used

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  • Control method and device for applying back pressure to annulus
  • Control method and device for applying back pressure to annulus
  • Control method and device for applying back pressure to annulus

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Embodiment Construction

[0051]In order to make the object, technical solution and advantages of the present invention clearer, the implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0052] Please refer to figure 1 , figure 1 It is a schematic diagram of the implementation environment of the control method for applying back pressure to the annular space provided by the embodiment of the present invention. The implementation environment includes: an oil and gas well 101 and a pressure control device 102 located at the wellhead of the oil and gas well 101 . When the oil and gas well 101 needs to be cemented, the casing 103 can be run in the oil and gas well 101 and the cement slurry 105 can be injected into the annular space 104 between the oil and gas well 101 and the casing 102 . During the waiting period of the cement slurry 105, the cement slurry 105 will experience weightlessness and induce air channeling. In ...

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Abstract

The invention discloses a control method and device for applying back pressure to an annular space, and belongs to the technical field of well cementing. The method comprises: after running the casing in the oil and gas well and injecting the cement slurry into the annular space between the oil and gas well and the casing, determining the real-time density of the cement slurry based on the time-varying function of the density of the cement slurry; The real-time density of , and the formation pressure equivalent density at the target location, determine the back pressure to be applied; apply this back pressure to the annulus. The back pressure gradually increases with the increase of time. In the early stage of the waiting period of the cement slurry, the back pressure applied to the annular space is small, which avoids the problem that the pressure in the annular space is greater than the fracture pressure of the formation. Thereby reducing the probability of lost circulation in oil and gas wells.

Description

technical field [0001] The invention relates to the technical field of well cementing, in particular to a control method and device for applying back pressure to an annular space. Background technique [0002] Cementing refers to the process of running casing in an oil and gas well, injecting cement slurry into the annular space between the oil and gas well and the casing, and sealing off the oil layer, gas layer and water layer in the oil and gas well after the cement solidifies. Cementing oil and gas wells can protect the casing in oil and gas wells and increase the production life of oil and gas wells, which is one of the important links in oil and gas well drilling engineering. [0003] During the period when the cement slurry changes from liquid to solid (that is, during the waiting period of the cement slurry), the cement slurry will lose weight, resulting in the reduction of the hydrostatic column pressure exerted by the cement slurry on the formation, and the hydrost...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B33/13E21B21/08
CPCE21B21/08E21B33/13
Inventor 郭建华郑有成李杰李维马勇徐冰青曹权胡锡辉李斌马旌伦徐璧华
Owner PETROCHINA CO LTD
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