Nano-micron pressure-bearing plugging agent for drilling fluid, and evaluation method thereof

Abstract

The invention relates to a nano-micron pressure-bearing plugging agent for a drilling fluid, and an evaluation method thereof, and belongs to the technical field of oil and gas drilling. The nano-micron pressure-bearing plugging agent for the drilling fluid comprises, by weight, 90-97 parts of micro-particles and 3-5 parts of nano-particles. The pressure-bearing plugging agent of the invention hasthe following advantages: the micron-particles form a low-porosity and low-permeability mud cake through particle bridging at the crack end of a near wellbore when meeting the micro-crack during drilling, and the surface effect of the nano-particles in a medium achieves rapid adsorption and aggregation film formation under the action of a positive pressure difference of the wellbore when meetingthe micro-crack during drilling in order to further reduce the permeability of the mud cake, so the micro-crack is successfully plugged, and the plugging effect is good; and the puging agent can passthrough meshes in a vibrating screen, and can be repeatedly used.

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...

AI Technical Summary

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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