Low-density environment-friendly drilling fluid capable of being repeatedly used for many times

Abstract

The invention relates to a low-density environment-friendly drilling fluid capable of being repeatedly used for many times, and the low-density environment-friendly drilling fluid separately used foran upper well section and a lower well section according to the well vertical depth. The low-density environment-friendly drilling fluid is characterized by comprising a part used for the upper well section and a part used for the lower well section, wherein the part used for the upper well section is prepared from the following components by mass percent: 0.3-0.6% of a high-polymer mud shale inhibitor, 0.2-0.5% of a flocculating agent, 2-8% of a micromolecule mud shale inhibitor, 0.2-0.5% of a filtrate reducer and the balance of clear water. The part used for the lower well section is prepared from the following components by mass percent: 8-20% of a micromolecule mud shale inhibitor, 0.5-2% of filtrate reducer, 1-3% of a mud shale blocking agent, 0.1-0.3% of an adhesive improver, 0.1% ofNaOH and the balance of clear water. Through the proportion, pollution resistance of the drilling fluid is relatively strong, so that the drilling fluid has relatively good environment-friendliness,is easy to degrade, has low viscosity and high shear, reduces equipment power loss under the same viscosity, improves sand carrying ability, is good in reducing friction resistance, is low in density,and weakens mechanical anti-collapse needs by strengthening chemical anti-collapse ability.

Description

technical field [0001] The invention relates to the technical field of drilling fluid in the process of oil and natural gas exploration and development, in particular to a low-density and environment-friendly drilling fluid that can be repeatedly used. Background technique [0002] Environmental protection is one of the most important issues in the world today. With the continuous improvement of human living standards, the awareness of environmental protection is increasing day by day. Whether the drilling fluid will cause toxic pollution to the environment, especially the groundwater during the drilling process, and whether the discharge of the drilling fluid after the drilling operation will cause toxic pollution to the environment are receiving special attention. Drilling fluid has become the primary object of environmental protection monitoring in drilling construction, and has become a bottleneck restricting the development and utilization of resource drilling. [0003...

AI Technical Summary

Problems solved by technology

In order to realize the clean production of oil and gas development, waste drilling fluid is generally treated by breaking the gel and separating the solid and liquid, and the separated liquid phase is reused. However, in the process of solid-liquid separation, a lot of production time and processing will be spent. In addition, in the process of reusing the liquid phase, the residual treatment agent is easy to ferment, which affects the failure of the newly added treatment agent, and the solid phase content of the drilling fluid is difficult to control, etc.

[0004] During the construction of natural gas horizontal wells, the wells in some blocks are to balance the formation collapse pressure, and the drilling fluid density is greatly increased, which leads to the intensification of collapse and leakage contradictions, and the increase in complex timeliness. Occurs frequently, seriously restricting the speed of drilling and production

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