Design and Evaluation of Mini-Frac Scheme in Shale Gas Exploration Well

Regional shale gas reservoir has different accumulation conditions,lithologies,physical properties,gas bearing properties and organic geochemistry indices,which lead to different hydraulic fracturing treatment strategies.It is necessary to carry out the mini-frac testing before main fracturing,in order to correctly understand the geological characteristics and the aim of main fracturing.Based on the comparison between the key formation parameter indices of a shale gas exploratory well (Well A) and the mature development parameter indices of American shale gas,the shale frac-ability conditions were analyzed,the specific design ideas and scheme for fracturing test were presented,and the mini-frac monitoring results were interpreted and evaluated systematically.The analysis indicated that,the mini-frac of shale gas needs higher pumping rate and larger liquid volume than conventional mini-frac design; the analysis on mini-frac test not only provided parameters required by the main fracturing design,such as reservoir pressure,permeability,fracture closure stress,fracture initiation and extending,but also could be used to judge the shale formation frac-ability and fracture network forming conditions.