Supercritical carbon dioxide completion fluid

Abstract

The invention belongs to the technical field of petroleum and natural gas well completion, and relates to a supercritical carbon dioxide completion fluid. The supercritical carbon dioxide completion fluid is prepared by mixing a preflush spacer fluid, a supercritical carbon dioxide flushing solution and a post-flush spacer fluid according to a volume ratio of 2-5:100:1-5. When the supercritical carbon dioxide completion fluid is used, the supercritical carbon dioxide flushing solution and a cementing slurry are prepared on the ground, the preflush spacer fluid and the post-flush spacer fluid are prepared, the preflush spacer fluid, the supercritical carbon dioxide flushing solution, the post-flush spacer fluid and the cementing slurry are sequentially pumped into a well head through a present fluid device in order to flush, the cementing slurry solidifies after the flushing, and an alkaline substance is injected from an annulus to remove carbon dioxide in the supercritical carbon dioxide flushing solution in order to prevent pollution of carbon dioxide to atmosphere and corrosion of carbon dioxide to bushings. The supercritical carbon dioxide completion fluid has the advantages of easily available raw materials, scientific principle, use convenience, good cementing effect, low cost, effective reduction of the thickness of mud cakes, and improvement of the cleanliness and roughness of the mud cakes.

Description

Technical field: [0001] The invention belongs to the technical field of oil and natural gas drilling and completion, and relates to a well completion fluid for improving cementing strength, in particular to a supercritical carbon dioxide well completion fluid. Background technique: [0002] In the process of oil and natural gas extraction, the quality of cementing is closely related to personal safety. If the quality of cementing is poor, oil and gas resources will be lost from the wellhead. Pipe, and the upward flow of fluid will pollute the water, prone to explosion, endangering personal safety. The quality of cementing depends on the bonding strength between the cement slurry and the casing and the well wall rock. Due to the percolation and adhesion of the drilling fluid, there is a layer of mud cake attached to the surface of the casing and the well wall rock. Therefore, the mud cake The cementing quality is determined by the bonding strength between the casing, the mud...

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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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