Drilling fluid for drilling of fractured igneous rock formation and preparation method of drilling fluid

Abstract

The invention relates to a drilling fluid for drilling of a fractured igneous rock formation and a preparation method of the drilling fluid in the field of petroleum drilling. The drilling fluid is prepared from components in parts by weight as follows: 1,000 parts of water, 3-4 parts of drilling fluid bentonite, 2-3 parts of sodium carbonate, 2-3 parts of a polymer coating agent, 2-3 parts of potassium polyacrylate or a metal cation polymer, 5-10 parts of an organic amine inhibitor, 20-30 parts of an anti-sloughing reinforced wall fixation agent, 20-30 parts of sulfonated phenol formaldehyderesin, 5-10 parts of a sulfonate copolymer filtrate reducer, 20-30 parts of walchowite, 10-20 parts of an anti-salt and temperature-resistant fluid loss agent, 20-40 parts of superfine calcium carbonate, 50-70 parts of potassium chloride, 0-10 parts of an organic anti-friction compound and 10-20 parts of a nano-micro blocking agent, and the weight is increased to 1.30-1.85 g/cm<3> with a density weighting agent. The drilling fluid has good temperature resistance and lubricating property and excellent inhibition property and anti-sloughing wall fixation property and can effectively prevent thefractured igneous rock formation from collapsing; the rock carrying capability of the drilling fluid can be substantially improved, repeated grinding of larger falling blocks nearby a drill bit is prevented, the frictional resistance is reduced, the mechanical drilling speed is increased, and underground safety is guaranteed.

Description

technical field [0001] The invention relates to the field of petroleum drilling, and more particularly, relates to a drilling fluid for drilling into fractured igneous rock formations and a preparation method thereof. Background technique [0002] The Tarim Basin in Xinjiang is rich in oil and gas resources, but the Permian and Ordovician fragmented igneous rock sections have complex drilling and frequent downhole accidents, which seriously threaten downhole safety and restrict drilling speed. The Permian igneous rock section is long (250-450m), the lithology is mainly basalt, dacite and tuff, interbedded with tuff and mudstone, poor cementation, strong heterogeneity, many weak points, broken strata, and developed fractures , the safe density window is narrow, and well collapse and leakage occur frequently during drilling. Ordovician formations have relatively low pressure and well-developed fractures, and the collapse pressure of igneous rock intrusions (plutonic rocks) is...

AI Technical Summary

Problems solved by technology

[0006] In order to solve the existing drilling fluid system existing in the prior art when drilling in fractured igneous rock formations, the igneous rock falling blocks are not easy to carry, the friction is large, the torque is abnormal, and it is easy to collapse, which seriously affects the safety of downhole drilling. Invention proposes a drilling fluid for drilling in fractured igneous formations