Study On Settling Stability Of High Temperature And High Density Water-based Completion Fluid

The deep oil testing period in deep well drilling operations is very long.The test oil and gas completion wells are prone to degradation and solidification after long-term high temperature standing,which causes the downhole complex conditions such as clogging of the test string,failure of test tools,and burying of the packer.Therefore,it is of great theoretical and engineering significance to study the stability of high temperature and high density water-based completion fluids.This article focuses on the stability evaluation method and control technology of high temperature and high density water-based completion fluids.There is no unified evaluation method for the long-term settlement stability of completion fluids,and the traditional evaluation methods have their own shortcomings.In this paper,based on multiple light scattering,using Turbiscan MA2000 stability analysis instrument,the kinetic curve and stability factor TSI were introduced to quantitatively evaluate the settlement stability of the system.Based on the principles of colloidal chemistry and microfluidics,the dispersion mechanism and rheological mechanism of water-based solid-phase suspensions were analyzed.The appropriate grading ratio of the weighting agent and the preferred dispersant were determined to be the coordination of high-density water-based completion fluids.Settling stability and rheological effective method.Test and completion fluids have higher requirements for rheological and sedimentation stability,and completion fluid rheology is related to static settlement stability.In order to obtain the relationship between rheological and sedimentation stability,the influence of the rheological parameters of the completion fluid on the settlement stability of the water-based completion fluid was studied using the kinetic graph and the stability factor TSI.Rheological parameters YP and Gel10min are closely related to the stability of sedimentation and play a decisive role in the settlement stability of the completion fluid.The ratio of API barite to fine barite was optimized by using the kinetic curve and the TSI,and the optimal compounding ratio was 7:3.The water-based completion fluid bentonite content,the key treatment agent dispersant,the type and amount of inhibitors were optimized,and a high density water-based completion fluid formula with a density of 2.0 g/cm3 was obtained:4%slurry +3%SMC+3%SMP-2+3%SMK+0.5%FZ-1+3%TS+0.8%DISP+0.4%Na2SO3+ barite(API barite:micropowder barite=7:3).Indoor laboratory analysis showed that the high-density water-based completion fluid was left at 180? for 10 days,and the completion fluid had good settling stability and rheological stability.