Study On High Temperature And High Pressure Drilling Fluid Inhibition And Dynamic Swell Meter

Clay shale is frequently met during oil and gas field exploration and development.The Clay shale can absorb moisture of the drilling fluid,then the shale will swell and disperse and the wellbore may collapse or shrink,which can possibly leading to pipe stuck and buried.It will delay the construction progress or even scraping the well.The swelling of clay shale is very important among the most factors of wellbore instability.To insure the safety and speed of drilling,additives which can decrease the swell of shale are added to drilling fluid.Swelling instruments are used to test and evaluate the performance of the additives and help to figure out the best adding amount.Swelling testing instruments are essential for the corporations of studying and producing additives which can decrease the swell of shale.They are also needed to guide the selection of mud system in drilling field,insuring the safety of drilling.At present,most of the swell testing instruments are designed based on NPT(normal pressure and temperature).They are operated manually and far from auto controlling.The resolution,parallelism and repeatability are not good enough.They can’t simulate the real condition of dynamic high temperature and high pressure drilling,unable to meet the needs of scientific research and production.This research is based on the Nation 863 Project and two geological survey projects sponsored by China Geological Survey of Ministry of Land and Resources.A dynamic high temperature and high pressure(HTHP)swell instrument is developed with independent intellectual property rights,filling in the blanks of dynamic HTHP swell instrument at home and abroad.The instrument can simulate both dynamic and HTHP condition(highest testing temperature:260℃,highest pressure:7MPa,Speed adjusting range:0-3000 rpm).It is digital and intelligent.The instrument can meet the requirements both of laboratories and drilling field.The swell testing instruments are used in the study of mud shale dynamic swelling under HTHP condition,selecting 2 additives system for different layers to decrease the swell of shale.The research includes 7 parts:the development of HTHP linear non-contact displacement sensors,the design of high precision temperature and pressure control system,the design of non-contact magnetic mixing system,the development of the parallel sample press machine,the development of control and data processing program on PC,the test of complete machine,the selection of additives system for different layers to decrease the swell of shale.The results of laboratory experiment and inspection experiment show that the swell testing instrument is intelligent and reliable.The figure is of high repeatability and parallelism.This swell testing instruments can totally meet the testing requirement of the mud shale swelling under HTHP condition.