Phosphoaluminate cement paste for deep sea cementing and shallow flow disaster prevention

Abstract

The invention discloses phosphoaluminate cement paste for deep sea cementing and shallow flow disaster prevention. The cement paste comprises the following components in parts by weight: 100 parts of mixed cement, 0.2-0.4 part of a defoamer, 3.5-4 parts of a fluid loss agent, 1-1.5 parts of a coagulant, 0.2-0.5 part of a retarder, 48-75 parts of seawater and 0-35 parts of a lightening admixture. The cement paste for deep sea cementing and shallow flow disaster prevention has the following advantages: (1) the development of low-temperature strength is quick and compressive strength at a low temperature is relatively high; (2) the thickening time is short and the thickening curve is approximate to right angle thickening, thereby effectively preventing the shallow flow disaster; and (3) the cement paste has the characteristics of zero free fluid content, relatively small filter loss, adjustable thickening time and the like.

Description

technical field [0001] The invention relates to a cement slurry for controlling shallow flow disasters, in particular to a deep-water cementing anti-shallow flow aluminophosphate cement slurry, which belongs to the field of deep-water oil and gas resource exploration, development, drilling and completion. Background technique [0002] With the increase of the proportion of offshore oil reserves, offshore oil exploration gradually develops into deep water areas to discover new oil resources. The influence of laminar flow is one of the biggest difficulties faced by deepwater cementing operations. [0003] Shallow flow includes shallow flow and shallow gas, and is trapped in the formation about 150-1000 meters below the mud line. Shallow flow is particularly harmful to cementing operations. On the one hand, shallow flow often causes excessive flushing of the borehole , the wellbore is deformed, and it is difficult to clean the wellbore, which affects the cementing, resulting i...

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Problems solved by technology

[0002] With the increase of the proportion of offshore oil reserves, offshore oil exploration gradually develops into deep water areas to discover new oil resources. The influence of laminar flow is one of the biggest difficulties faced by deepwater cementing operations

[0003] Shallow flow includes shallow flow and shallow gas, and is trapped in the formation about 150-1000 meters below the mud line. Shallow flow is particularly harmful to cementing operations. On the one hand, shallow flow often causes excessive flushing of the borehole , the wellbore is deformed, and it is difficult to clean the wellbore, which will affect the cementing, resulting in poor cementation of the cementing interface and the generation of gaps

On the other hand, in the cementing project, during the waiting process of the cement slurry, the shallow high-pressure fluid will gushes out of the weak sedimentary formation and invades into the cement slurry, causing fluid channeling and channeling, which affects the cementing performance of cement stone. The annular sealing effect of cement is reduced, which brings risks to the cementing operation, which may seriously cause disasters such as blowout, wellhead collapse, and fire, endangering the operation and production safety of the entire well. The existing cement slurry system flows in deep water and shallow layers. It is difficult to solidify in the environment, and the thickening conversion time is long, and the low-temperature strength development performance is also poor

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