Applicability Evaluation And Application Of Gas Drilling In The Demonstration Area Of Shale Gas In Southern Sichuan

The natural gas reservoir in southern Sichuan Zhaotong shale demonstration zone has high hardness,strong abrasiveness,poor drillability and leakage characteristics of multi layer,caused by drilling in the area of low drilling rate,long drilling cycle and high drilling cost,application of gas drilling technology can greatly improve the mechanical drilling speed,to solve the above problems.However,not all applicable geological conditions and reservoir types of gas drilling,formation water,and the air hole collapse are likely to lead to serious accidents of gas drilling,the gas drilling is difficult to achieve the desired effect.Based on the data of geology,drilling,logging and so on,this paper comprehensively grasps the geological structure characteristics of the Zhaotong shale block,and provides the necessary geological basis for the study of gas drilling adaptability evaluation.Effect of comprehensive analysis of the formation lithology and formation water outlet characteristics of gas drilling,combined with the characteristics of strata,the adaptability evaluation of the area of gas drilling formation.According to the established calculation model of formation water,determine the water layer according to the logging data,the prediction method of the water layer and the time difference and bilateral acoustic binding to the resistance data,citing seepage mechanics principle to establish the calculation model of formation water quantity.Establish the relationship model between rock drillability and rock mechanics parameter,combined with field data of the block,the block formation drillability profile,and the drillability changes identified in this block have speed potential by gas drilling.According to the Zhaotong demonstration area of shale gas drilling carried out the research on the applicability of the conventional process,appear on the wall off the block,well leakage,sticking problems in gas drilling can be through the use of air hammer and rock bit,bottom hole pressure control method can effectively avoid.For the southern Sichuan complex lithology,strata can provide theoretical support for poor drilling shale gas well construction,ensure the gas drilling to better play its advantages,maximize the construction safety assurance of gas drilling,improve economic efficiency.