Naturally-degradable environment-friendly drilling fluid

Abstract

The invention provides a naturally-degradable environment-friendly drilling fluid. The drilling fluid comprises the following components in parts by weight: 3.0%-7.0% of a shale inhibitor, 1.0%-3.0% of a natural anti-sloughing agent, 1.0%-5.0% of a natural blocking agent, 0.3%-0.5% of a natural viscosity-increasing cutting agent, 1.5%-3% of a natural fluid loss agent, 0.5%-4.0% of a lubricant, 0.1%-0.3% of polyhydroxymethyl hydroxyethyl siloxane, 0.02%-0.07% of an antioxidant and the balance of water. The drilling fluid can be applied to safe drilling and completion construction of exploratorywells, special process wells and horizontal wells in Changqing areas, six functions of stabilizing a well wall, preventing leakage and stopping leakage, carrying sand and suspending sand, purifying aborehole, protecting a reservoir and protecting the environment are realized, the drilling fluid has the characteristics of no biotoxicity, no chemical toxicity, biodegradability, environmental protection, strong anti-collapse ability, good plugging effect, effective reduction of stratum collapse ability, smooth and compact mud cake like a film, good lubricity, low damage to a low-porosity, low-permeability and low-abundance oil reservoir, and simple and feasible formula and slurry preparation process.

Description

technical field [0001] The invention belongs to drilling fluid, in particular to a naturally degradable and environment-friendly drilling fluid. Background technique [0002] The horizontal wells of Ansai Oilfield are located in the central and eastern part of Changqing Oilfield, which is also a highly sensitive area for environmental protection. Through horizontal well layout, the Chang 6 and Chang 8 oil layers of the Yanchang Formation are efficiently developed to increase single well production and recovery. The wellbore structure of horizontal wells in Changqing Ansai Oilfield is generally a two-split structure, and there are a series of drilling fluid technical problems in the drilling construction process that need to be solved through in-depth research. The first is the technical problem of wall instability in the long open hole. There are large sections of mud shale in the top formations of Zhiluo Formation, Yan'an Formation, Fuxian Formation and Yanchang Formation ...

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Problems solved by technology

[0003] In order to overcome the existing problems of non-environmental protection and poor plugging effect, the present invention provides a naturally degradable and environmentally friendly drilling fluid. The present invention is suitable for safe drilling of exploratory wells, special process wells, and horizontal wells in Changqing area, and natural degradation and environmental protection of well completion. Drilling fluid, which is non-biologically toxic, non-chemically toxic, biodegradable and environmentally friendly, has strong anti-slump ability for a long time, good plugging effect, and can effectively reduce the ability of formation collapse. The mud cake is smooth and dense like a film, and has good lubricity. Low damage to low-porosity, low-permeability and low-abundance reservoirs, with the characteristics of easy implementation of formula and process

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