Research In Situ Exploitation Method And Well Pattern Optimization Of Oil Shale In Block A Of Jilin Oilfield

The Block A of Jilin Oilfield is located in Songliao Basin of China,which contains rich oil shale and has high development potential.The oil shale in Block A is deep and discontinuous,the single layer of oil shale is thin,and there is a thick mudstone interlayer developed.It is not applicable to surface methods.Therefore,it is necessary to optimize the appropriate in-situ mining method and the well pattern.This paper takes the oil shale in Block A of Jilin Oilfield as the research object and draws the following conclusions through laboratory experiments and numerical simulation methods.（1）The law of porosity and permeability changing with temperature after pyrolysis of oil shale is studied by using CT and empirical formula.The results show that the pyrolysis stage of kerogen of oil shale in Block A is mainly in the range of 250℃～550℃,and the porosity and permeability of oil shale increase greatly.（2）The most mature in-situ mining method is electric heating,which has the disadvantages of small heating radius.So,the thermal fluid assisted electric heating was designed and studied by numerical simulation.Without artificial fracturing,the injected hot fluid only stays in the wellbore and near the wellbore area,unable to play the role of convective heating of fluid.Therefore,artificial fracturing is needed.（3）Under artificial fracturing,the fractures with different cluster intervals are designed.The heating effect and reservoir physical properties of different methods are studied.The results show that the optimal fracture cluster interval is 5m,and the optimal heating method is thermal CO₂assisted electric heating.（4）The Horizontal well pattern is designed,which is triangular,rectangular,square,and row pattern.The heating effect and heat loss of different well patterns are studied,and the results show that the row well pattern is the best well pattern（5）The key parameters were optimized by using numerical simulation,including heating cable temperature and power,CO₂ gas temperature,injection rate,and well pattern rotation strategy.Finally,the pilot test scheme was designed.