Marine quaternary formation drilling fluid

Abstract

The invention belongs to the technical field of drilling, and provides marine quaternary formation drilling fluid. The fluid is prepared from, by weight, 1000 parts of water, 50-70 parts of bentonite,1-5 parts of alkali, 0.1-1 part of fluid loss additive, 0.1-2 parts of thickener and 0.1-2 parts of acrylic grafted starch copolymer. The invention further provides a method for preparing the marinequaternary formation drilling fluid and application thereof in the drilling and core removal process of the marine quaternary formation. The marine quaternary formation drilling fluid has excellent wall protection performance, and in the process of open hole core removal of the marine quaternary loose formation, the problems that hole walls of sand formation easily collapse, sand gushing and drillbit burying occur, hole walls of water-sensitive muddy formation are reduced in diameter, the bottoms of holes are not clean and the like are better solved.

Description

technical field

[0001] The invention belongs to the technical field of drilling, and relates to a marine Quaternary formation drilling fluid. Background technique

[0002] Quaternary strata are complex and unstable, and there have been many glacial ages, which is the age when loose deposits were formed, mainly sandy unconsolidated strata and clay strata, among which sandy strata are prone to collapse and instability, and there are well sections with big bellies; water sensitive The hard plastic clay layer is easy to shrink the hole wall.

[0003] The marine environment is different from land, and when drilling the Quaternary strata in the ocean, it is easily affected by tides and wind waves. The construction of deep wells often needs to be carried out during the small tide period and when the wind is hourly (wind force ≤ 7, generally 5-6). Therefore, a simple and efficient drilling and coring process is often adopted to avoid the influence of adverse sea conditions during ...

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