A supercritical carbon dioxide completion fluid

Abstract

The invention belongs to the technical field of oil and natural gas well completion, and relates to a supercritical carbon dioxide well completion fluid, which consists of a pre-spacer fluid, a supercritical carbon dioxide flushing fluid and a post-spacer fluid in a volume ratio of 2‑5:100:1‑5 Proportional mixing composition. When using, first prepare supercritical carbon dioxide flushing fluid and cement slurry on the ground, then prepare pre-isolating fluid and post-isolating fluid, and pump the pre-isolating fluid in sequence through the existing fluid equipment at the wellhead , supercritical carbon dioxide flushing fluid, rear spacer fluid and cementing cement slurry for flushing. After flushing, the cementing cement slurry is solidified and alkaline substances are injected from the annulus to remove carbon dioxide in the supercritical carbon dioxide flushing fluid and prevent carbon dioxide pollution Atmospheric and corrosive casing; its raw materials are easy to obtain, its principle is scientific, it is convenient to use, it has good cementing effect, low cost, effectively reduces the thickness of mud cake, and improves the cleanliness and roughness of mud cake.

Description

[0001] Technical field: [0002] The invention belongs to the technical field of oil and natural gas drilling and completion, and relates to a completion fluid that improves cementing cementation strength, in particular a supercritical carbon dioxide completion fluid. [0003] Background technique: [0004] In the process of oil and natural gas exploitation, the quality of cementing is closely related to personal safety. If the cementing quality is poor, oil and gas resources will be lost from the wellhead. The mutual channeling of different pressure layers affects the rational development of oil and gas fields. After the channeling, formation fluids are easy to corrode the casing. In addition, the fluid flowing up will pollute the water source, easily explode, and endanger personal safety. The quality of cementing depends on the cementing strength of cement slurry and casing and borehole rock. Due to the infiltration and adhesion of drilling fluid, there is a layer of mud cake attac...

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Problems solved by technology

In addition, residual drilling fluid will reduce the density of cement slurry, and its incompatibility will affect the curing process of cement slurry, thereby reducing the bonding strength

In order to make the mud cake and cement slurry have a better cementation quality, the completion fluid is used to pretreat the mud cake at the drilling site. At present, there are mainly three types of completion fluids used at home and abroad: surfactant completion fluid, solid Phase completion fluid and clay-free solid phase completion fluid are divided according to the composition ratio of the completion fluid. The above three completion fluids are all water-based completion fluids, which are highly effective in water-sensitive formations such as shale and shale formation Reduce, moreover, these three kinds of completion fluids need to add various chemical and physical components, and the cost is high

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