Rock Drillability Analysis Based on Fractal Method in Deep Sandstone Formation
Wang Hai-miao · Science Technology and Engineering · 2011
The primary method of measuring rock drillability is selecting well coring as object,measuring rock mechanical property and doing drillability test in micro-drilling method during drilling.However,field application shows that the sampling cost is high and the test period is long.It can't be directly used on field and makes great difficulty to field application.Sandstone coring clastics distribution in different confining pressure using filter approaches is analyzed and find that it is fractal distribution in sandstone coring breakage clastics.The fractal dimension D value of clastics distribution is different under different confining pressure tests.The fractal dimension of sandstone fragment distribution augments with the increasing of confining pressure.The causes of fractal dimension increasing are explained and physical mechanics of clastics fractal distribution are studied.Furthermore the relationship among coring fractal dimension,drillability and confining pressure is analyzed.It is the elements of describing drillability using upturned detritus during drilling.It is a new approach of studying drillability.