Research On The Rock Drillability Of Igneous Rock

Presently, there are many methods for rock drillability analysis in well drilling engineering, which are inner micro-bit testing, logging and drilling rate model. The drillability of routine rock stratum can be calculated magnificently by former testing method. But to the deeper volcanic rock stratum, routine methods can not truly calculate drillability, just because of its high rigidity, high abrasive intensity and bit serious abrasion.The abrasion mechanism and the influential factors on rock drillability are elaborated in the article. The characteristics of abrasion of volcanic rock are analyzed in Changling fault. The model is built over normative mineral component. Coefficients of equivalent content of quartz are determined.Based on field actual drilling data, statistical analysis has been done, which are about bit abrasion used in drilling deeper Changling fault volcanic rock stratum.The initial ROP and the grinding factor are calculated respectively by wear equation and drilling rate model using logging data.Take hard mineral content (equivalent quartz content) as study object, the correlativity is analysed respectively among equivalent quartz content, grinding factor, bit attrition rate and drillability. The relativity of equivalent quartz content with the other three factors is well.Then the volcanic rock abrasive drillability is determined by the relationship between equivalent quartz content and it.