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Positive injection back squeeze well cementation method for low pressure and leaky well

A lost well and low pressure technology, which is applied in wellbore/well components, earthwork drilling, sealing/isolation, etc., can solve the problems of low replacement efficiency of sealing section and insufficient cement return height, etc., so as to avoid significant cost increase, The effect of improving cementing quality and avoiding production hidden dangers

Active Publication Date: 2017-04-05
中石化石油工程技术服务有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a cementing method for low-pressure and easy-to-leakage wells with positive injection and reverse extrusion, which can effectively solve the problems of insufficient cement return height caused by cementing leakage and low replacement efficiency of the sealing section, and reduce the waste of cement slurry caused by leakage

Method used

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  • Positive injection back squeeze well cementation method for low pressure and leaky well
  • Positive injection back squeeze well cementation method for low pressure and leaky well
  • Positive injection back squeeze well cementation method for low pressure and leaky well

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Effect test

Embodiment 1

[0097] Well JP-302 was cemented using the above-mentioned cementing method of forward injection and reverse extrusion for low-pressure and easy-to-lose wells. Loss occurred during normal cementing in Well JP-302, and the return height of the cement slurry was insufficient, so back extrusion was carried out.

[0098] The technical casing of Well JP-302 lost when running the casing, and the drilling fluid established normal circulation after plugging and before cementing. The cementing design and construction are carried out according to the one-time sealing of the whole well section. Leakage occurs during the cement replacement process. According to the leakage amount and the pressure before collision, it is estimated that the cement return height is 1500m; after waiting for 12 hours, inject 10m of flushing fluid 3 , "back extrusion" cement slurry 30m 3 . Such as image 3 As shown, the sound amplitude logging shows that the unconnected well section of the annulus is only 70m...

Embodiment 2

[0100] Well JP-329 was cemented using the above-mentioned cementing method of forward injection and reverse extrusion for low-pressure and easy-to-lose wells. The drilling fluid in Well JP-329 could not establish normal circulation before cementing, so the design of "positive injection" and "back squeeze" was adopted.

[0101] After the casing was run in Well JP-329, circulation could not be established due to severe leakage, and the thick slurry in the well could not circulate out of the well. The well was constructed by "positive injection and back extrusion". "Positive injection" is sealed to the bottom of the leakage layer, and the cement slurry is not added; after 12 hours of positive injection, back squeeze the flushing fluid, isolation slurry and low-density cement slurry in sequence. According to the wellhead pressure, after back-extruding part of the cement slurry, the pressure slowly drops to the minimum and then rises significantly, and the back-extrusion cement slu...

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Abstract

The invention relates to a positive injection back squeeze well cementation method for a low pressure and leaky well. The method comprises the steps that 1) drilling fluid section circulating is carried out during a casing running process; 2) after casing running, drilling fluid in the well goes to the top, and if normal cycle can be established, fixed displacement cycle is carried out at least two periods, otherwise positive drilling fluid injection is carried out to ensure unobstructed hohlraum; 3) cement slurry is positively injected and sealed to the bottom of a leak layer or the formation to bear ensured cement back height; 4) small displacement test squeeze is carried out to squeeze the leak layer through. In the step 4), if the pressure of the squeezed wellhead exceeds P, construction is stopped; and if the pressure of the squeezed wellhead does not exceed P, back squeeze construction is carried out according to the designed back squeeze cement slurry amount and the slurry column structure. According to the well cementation method, the problems of insufficient cement back height and low replacement efficiency of a sealing section, which are caused by well cementation leak, are effectively solved; cement slurry waste caused by leak is reduced; and obvious cost increasing caused by used ultra-low density cement slurry and hidden production dangers caused by loose grading hoop sealing are avoided.

Description

technical field [0001] The invention belongs to the technical field of oil and gas well construction and construction, and in particular relates to a well cementing method for a low-pressure easy-to-leakage well with forward injection and reverse extrusion. Background technique [0002] Cementing is a key operation link in the process of oil and gas well construction. Realizing the structure and sealing integrity of the cement sheath in the annular space formed by the casing and the wellbore is the basic requirement of the cementing project. However, when cementing wells with low pressure and easy leakage, due to the low pressure bearing capacity of the formation, the cement slurry enters the leaky layer under the pressure of the dynamic fluid column in the annular space, resulting in insufficient cement return and indirectly sacrificing the improvement of displacement efficiency, resulting in cementing Poor quality will affect the normal production and service life of oil a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B33/13
CPCE21B33/13
Inventor 李明忠李正国毕明清谢海涛赵毅博魏钊何斌斌蒋记伟
Owner 中石化石油工程技术服务有限公司
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