Research On The Control Methods Of Rheology And Wall-building Properties Of High-density Water-based Drilling Fluids

The rheological property and building capacity of high density water-base drilling fluid deteriorate with large weighting material added,including high solid content,high liquid viscosity and poor rheological property.Therefore,It's too difficult to adjust and control both of them.film-forming technique,temporary plugging technique and sealing technology are often used in filed operation with some but very little effect.This problem hasn't been solved essentially while two properties can't harmonize with each other.As a consequence,the research on the controlment between rheological property and building capacity of high density water-base drilling fluid is an extremely urgent technical problem.This article analyses influence factor on rheological property and building capacity.The analysis result indicates that clay and treating agent impact little than barite on them while grain size selection of barite shows most prominent influence.However,there are some differences between the influential mechanism of these two properties and their requests.The requests has been calculated based on bearing theory,ideal filler theory and close packing theory.Conbine with requests,this paper develops an effective solution for their control.This article segmented screening the API barite in quantity by filter and then compound the various diameter with barite which has been screened.The experiments confirmed the validity of controlment.According to the theory of bearing,rheology requires the ratio of secondary particles and primary particles must be not more than 0.225,and the large the secondary particle size,the better.According to the theory of close packing and ideal filler,well building property requires the ratio of secondary particles and primary particles must be not more than 0.155.The experimental results show that the rheology and well building property of high density water-base drilling fluid is good,the coordination is good too,when the ratio of secondary particles and primary particles is 0.155.The rheology and well building property of high density water-base drilling fluid become better and so do coordination,when the ratio of secondary particles and primary particles become from 0 to 0.155,or from 1 to 0.155.So the ratio of secondary particles and primary particles is the key to control the rheology and well building property of high density water-base drilling fluid.It proves that the ratio of secondary particles and primary particles is the key to control the rheology and well building property of high density water-base drilling fluid,and the rheology and well building property of high density water-base drilling fluid will be greatly improved by controlling the ratio of secondary particles and primary particles.