A pressure-bearing plugging agent for nano-micro drilling fluid and its evaluation method

Abstract

The invention relates to a pressure-bearing plugging agent for nano-micron drilling fluid and an evaluation method thereof, belonging to the technical field of oil and gas drilling. The pressure-bearing plugging agent for micron drilling fluid comprises 90-97 parts by weight of micron-sized particles and 3-5 parts by weight of nano-sized particles. The beneficial effect of the pressure-bearing plugging agent of the present invention is that when micron-sized particles encounter micro-fractures, they form a mud cake with low porosity and low permeability through particle bridging at the fracture end near the wellbore. , when micro-fractures are drilled, it can quickly absorb and accumulate to form a film under the action of positive pressure difference in the wellbore, further reducing the permeability of the mud cake, thereby successfully plugging micro-fractures with better plugging effect. In addition, this plugging agent can pass through the vibrating screen The mesh can be used repeatedly.

Description

technical field [0001] The invention belongs to the technical field of oil and gas drilling, and in particular relates to a pressure-bearing plugging agent for nano-micron drilling fluid and an evaluation method thereof. Background technique [0002] At present, during the drilling process of oil and gas wells, the pressure-bearing plugging agent used in the drilling fluid can have a better effect of plugging the formation micro-fractures when the drilling encounters leakage. Commonly used plugging agents include: calcium carbonate particles, graphite powder, softenable and deformable asphalt, and fine fiber plugging agents. [0003] The existing plugging agent that can block micro-fractures in the formation, the particle size can pass through the water hole of the downhole drilling tool and squeeze into the leakage zone, but cannot pass through the mesh of the ground vibrating screen, and will be screened out by the vibrating screen after circulating to the ground for one c...

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Problems solved by technology

[0003] The existing plugging agent that can block micro-fractures in the formation, the particle size can pass through the water hole of the downhole drilling tool and squeeze into the leakage zone, but cannot pass through the mesh of the ground vibrating screen, and will be screened out by the vibrating screen after circulating to the ground for one cycle. Therefore, the commonly used plugging agents are all "one-time" plugging agents, which greatly reduces the timeliness of sealing micro-fractures / micro-pores in the formation, and the screened plugging agents cannot be reused, resulting in waste of materials and increased costs.

[0004] At the same time, there is no standard evaluation method for plugging agents in the oil and gas industry. The use and maintenance of plugging agents at drilling sites are still based on past experience, and there is a lack of experimental results as a guide.

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