Environment-friendly, low-damage and clay-free deep water constant-rheology drilling fluid

Abstract

The invention discloses an environment-friendly, low-damage and clay-free deep water constant-rheology drilling fluid comprising the following components in percentage by mass: 0.35-0.5% of alkalinity regulator, 0.4-0.5% of tackifying agent, 7-10% of inhibitor, 2.1-2.5% of filtrate reducer, 3-5% of lubricating agent, 0.3-0.5% of mud cake quality modifying agent, 0-0.8% of viscosity reducer, 0-61.2% of weighting agent and the balance of seawater. The environment-friendly, low-damage and clay-free deep water constant-rheology drilling fluid is free of biotoxicity, easy to biologically degrade and environment friendly; the EC50 value of the drilling fluid is larger than 120000mg / L, the rock core permeability recovery rate is 87.37%, a polluted segment is shorter than 0.5cm, the damage of foreign fluid to a hydrocarbon reservoir can be reduced, and the ocean environment can be effectively protected; the drilling fluid disclosed by the invention can resist to the temperature of 120 DEG C, has the controllable density of 2.0g / cm<3> and constant dynamic shearing force at different test temperatures after being subjected to hot rolling for 16h, and is favorable in thixotropy, relatively strong in shearing dilutability, easy to form a flat plate flow and strong in rock carrying capacity. By using the environment-friendly, low-damage and clay-free deep water constant-rheology drilling fluid, the in-well pressure kick, the ECD (Equivalent Circulating Density) value and the borehole slurry leakage can be effectively reduced, the slurry loss of a vibrating screen is avoided, the borehole cleanness is improved, and the non-production operation time is saved.

Description

technical field [0001] The invention relates to the field of petroleum, especially the field of drilling and completion fluids for offshore oil wells, in particular to an environment-friendly, low-damage, clay-free deep-water constant-rheology drilling fluid. Background technique [0002] In recent years, with the continuous growth of global crude oil consumption, the production of crude oil on land and in shallow seas can no longer meet the demand, and offshore energy exploitation has moved from shallow sea to deep sea. Different from shallow sea energy exploitation, the drilling environment and temperature involved in deep sea drilling are special. When deep sea drilling reaches a water depth of 1500m, the temperature of the mud line is around 4°C. In some special areas, it may even drop to around 0°C. Under the environment, low-temperature thickening and shale shaker slurry will occur when conventional drilling fluid is used, especially under low-temperature dynamic shear...

AI Technical Summary

Problems solved by technology

Solve the problems of deep water drilling fluid thickening at low temperature, shale shaker running out of slurry, especially under low temperature dynamic shear force and low shear rate, resulting in large viscosity fluctuations, resulting in lost circulation, high ECD, and difficult pressure control

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