Analysis Of Easy Leakage Formation Features And Reserach On Plugging Formula While Drilling In Tuoputai Area

Through elastic graphite, a new drilling plugging material, is introduced. I usedthe method of compatibility test and plugging experimental of high temperature sandbed, to evaluate the effect of elastic graphite and other plugging agent oncompatibility and plugging. I optimized the plugging agents meeting the requirementsof plugging while drilling. Additionally, when it comes to the permeable formationand fissured formation in Tuoputai area, another two methods of pluggingexperimental of high temperature sand bed and experimental of fissure are used tooptimize plugging formula while drilling.The main findings of this paper are as following:(1) The investigation of plugging present situation and the analysis of easyleakage formation features are completed. The results indicate that the loss inTuoputai area is based on permeability loss and fissured loss. Meanwhile, the depth ofleak zone is great, the leakage segment is long and leak points are uncertain. Themethod of plugging while drilling can increase the success rate of plug and lower itsdifficulty.(2) A new drilling plugging material, called elastic graphite, is introduced. Themethods of compatibility test and plugging experimental of high temperature sand bedare used to evaluate the effects of elastic graphite on compatibility and plugging. Theresults indicate that elastic graphite have good compatibility with basic mud, meaningit affects little on rheology and filtration of basic mud. There is no chemistry reactionbetween elastic graphite and the drilling fluid composition. Under high temperature,elastic graphite has stable property.(3) The method of compatibility test and plugging experimental of hightemperature sand bed is used to evaluate the effects of Leiter plugging agent and otherplugging agent on compatibility and plugging. The result indicate that Leiter pluggingagent have strong ability of plugging, good compatibility and ability of resistance tohigh temperature. The plugging agent which suited plugging while drilling in high temperature is optimized.(4) The research on mechanism of plugging while drilling is finished. When itcomes to permeability loss and fissured loss, plugging formula while drilling isoptimized, including the formula is suited to0.9mm~1.7mm sand bed,1mm fissuresand2mm fissure.