High-efficient water-based well drilling fluid with fast absorption, strong inhibition and low damage

Abstract

The invention discloses a high-efficient water-based well drilling fluid with fast absorption, strong inhibition and low damage, which comprises the following components: 100 parts of seawater or fresh water, 2-5 parts of inorganic salt, 0.2-0.8 part of coating inhibitor, 1.5-3.5 parts of fluid loss additive, 2-4 parts of strong inhibitor, 2-4 parts of lubricant, 0.1-0.5 part of shear strength improving agent and 30-150 parts of weighting agent. The well drilling fluid has strong inhibition and has good rheological property and stable system performance during the whole well drilling process,even a large quantity of highly easily hydrated and dispersed cuttings exist for invasion of sewage, the viscosity of the well drilling fluid is basically controlled to be about 50s.

Description

technical field [0001] The invention relates to a water-based drilling fluid. Background technique [0002] For complex formations, especially mud shale formations with high montmorillonite content, drilling with conventional water-based drilling fluids will often cause downhole complex situations, which are manifested in the following aspects: [0003] (1) For active mud shale formations that are prone to mud formation, if the drilling fluid has poor inhibition, it is easy to increase the dynamic shear force and static shear force of the drilling fluid, resulting in poor rheology of the drilling fluid and increased pump pressure , in severe cases, the formation will be leaked, which will affect the normal drilling speed to a certain extent. [0004] (2) For expansive shale formations, if the drilling fluid has poor inhibition, borehole diameter shrinkage is likely to occur; while for dispersed shale formations, wellbore collapse is prone to occur, resulting in wellbore ins...

AI Technical Summary

Problems solved by technology

[0003] (1) For active mud shale formations that are prone to mud formation, if the drilling fluid has poor inhibition, it is easy to increase the dynamic shear force and static shear force of the drilling fluid, resulting in poor rheology of the drilling fluid and increased pump pressure , in severe cases, the formation will be leaked, which will affect the normal drilling speed to a certain extent

[0004] (2) For expansive shale formations, if the drilling fluid is not well inhibited, borehole diameter shrinkage is likely to occur; while for dispersed shale formations, wellbore collapse is prone to occur, resulting in wellbore instability

Whether it is the collapse of the well wall or the shrinkage of the well wall, it is easy to cause the difficulty of tripping and affect the ROP

[0005] (3) Water-based drilling fluids with poor inhibition can easily migrate reservoir particles, cause pore throat blockage, reduce effective permeability of reservoirs, and cause greater damage to reservoirs