Salt-resistant strong-inhibitive reservoir-protecting drilling fluid

Abstract

The invention relates to a salt-resistant strong-inhibitive reservoir-protecting drilling fluid which comprises the following components in part by weight: 2-4 parts of bentonite, 1-3 parts of salt-resistant clay, 0.1-0.2 part of sodium carbonate, 100 parts of water, 0.4-0.8 part of tackifier ST-MH, 2-3 parts of fluid loss additive KNT, 0.2-0.6 part of shale inhibitor, 2-6 parts of organic composite sylvite BPC, 2-3 parts of bridge additive and 2-3 parts of biological enzyme storage agent. The drilling fluid has strong salt bed resistance, pollution resistance and inhibitive ability.

Description

technical field [0001] The invention relates to an additive used in the field of oil field drilling, in particular to a salt-resistant, strong-inhibiting, and reservoir-protecting drilling fluid. Background technique [0002] In some oil fields, there are salt-gypsum layers in the process of exploration and development, which seriously pollute the drilling fluid, wellbore spalling and reservoir leakage and other problems. The main manifestations are that there are large sections of gypsum-salt layer in the upper part, the drilling fluid is seriously polluted during the drilling process, the fluid loss is large, and the rheology is difficult to control; the large section of strong water-sensitive shale in the lower part is very easy to cause wellbore shrinkage due to water absorption and swelling , spalling; the porosity of the reservoir is large, the leakage continues during the drilling process, and the drilling fluid and harmful solid phase seriously pollute the reservoir....

AI Technical Summary

Problems solved by technology

[0002] In some oilfields, there are salt-gypsum layers in the process of exploration and development, which seriously pollute the drilling fluid, wellbore spalling and reservoir leakage, etc.

The main manifestations are that there are large sections of gypsum-salt layer in the upper part, the drilling fluid is seriously polluted during the drilling process, the fluid loss is large, and the rheology is difficult to control; the large section of strong water-sensitive shale in the lower part is very easy to cause wellbore shrinkage due to water absorption and swelling , spalling; reservoir porosity is large, continuous leakage during drilling, drilling fluid and harmful solids seriously pollute the reservoir

[0003] Although ordinary polymer drilling fluids and undersaturated / saturated brine drilling fluid systems have strong salt resistance, they are weak in inhibiting shale expansion, diameter shrinkage, and reservoir protection, and cannot fundamentally solve salt-gypsum layer pollution, Borehole spalling, reservoir protection and other problems; although water-in-oil drilling fluid can solve the above problems, due to formation leakage, a large amount of drilling fluid will be lost to make the cost too high, and the environment is polluted and the reservoir protection effect is good

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