A drilling fluid with chemical reverse osmosis function

Abstract

The invention relates to a drilling fluid with a chemical reverse osmosis function and belongs to the technical field of water-based drilling fluids for petroleum drilling. The drilling fluid is prepared from raw materials such as a nano-microemulsion blocking agent, a nano blocking agent and a reverse osmosis agent. The drilling fluid can be formed into a semipermeable membrane with high membrane efficiency on the wall of a shale well under the action of the nano-microemulsion blocking agent and the nano blocking agent; the reverse osmosis agent is used for keeping the water activity of the drilling fluid less than or equal to the water activity of stratum shale, so that reverse chemosmosis differential pressure can be generated between the drilling fluid and the wall of the shale well; consequently, water in the drilling fluid is prevented from penetrating and migrating into the shale stratum and the purpose of stabilizing the wall of the well is achieved. Besides, the drilling fluid provided by the invention is used for solving the problems that in the prior art, only the blocking capacity is paid attention to and the chemosmosis driving force of water migration of the drilling fluid and the shale is neglected, and as a physical blocking method is adopted, the semipermeable membrane has seepage phenomenon so that a solvent medium is incapable of completely preventing water from penetrating through the membrane, and as a result, collapse accidents caused by unstable rock on the wall of the well still occur.

Description

technical field [0001] The invention relates to a drilling fluid with chemical reverse osmosis function, which belongs to the technical field of water-based drilling fluid for petroleum drilling. Background technique [0002] It is well known that the entry of water into the mud shale formation near the borehole wall is one of the main reasons for the instability of the borehole wall. On the other hand, the strength reduction of shale rocks after absorbing water will generate expansion pressure, which will cause changes in mechanical properties, which is not conducive to the stability of the wellbore wall, resulting in the instability and collapse of the wellbore rocks. Therefore, when drilling with water-based drilling fluid, all technical measures must be taken to prevent water from entering the formation. Generally, the driving forces for water entering the formation mainly include: static pressure and dynamic pressure difference, osmotic pressure difference and capillar...

AI Technical Summary

Problems solved by technology

[0004] However, according to domestic and foreign studies, the semi-permeable membrane of natural mud shale is a non-ideal membrane. The leakage phenomenon of this non-ideal membrane makes the solvent medium unable to completely prevent water from permeating the membrane, which will still lead to instability of the well wall rock. Collapse accident

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