Evaluation Of Horizontal Well Productivity In Shale Gas Reservoirs

Shale gas reserves are abundant in the world,with considerable prospects for exploration.The prediction of reservoir production and reserves is an important component of reservoir engineering.Therefore,it is very important to evaluate the productivity of shale gas horizontal wells.This paper analyzes the mode of occurrence of shale gas,the mechanism of migration output,and the mechanism of seepage,and analyzes the applicability of empirical methods,modern production decline methods,and simulation prediction methods as methods for calculating shale gas production and reserves.The detailed discussion and comparison of its models were carried out.The basic reservoir characteristics of the target shale gas reservoir are clarified,and the production characteristics of the typical wells are selected.The applicable methods are selected to predict the production,and control factors are analyzed to provide the reference to the prediction of shale gas in China.It can be concluded from the study that the empirical method can only analyze the production data with constant or approximately constant downhole flow pressure,and require stable data.The main difference between different methods is that the applicable flow regime is different.The empirical method is mainly applicable to linear flow and boundary control flow.The modern production decline analysis method is applicable to unstable flow and boundary control flow,and the simulation prediction method is applicable to all flow states.The average daily gas production in the first year of gas wells has a good linear relationship with the forecasted final harvest(EUR),and EUR shows a significant upward trend with construction and production rounds.The higher the content of adsorbed gas in the reservoir,the greater the contribution to production in the middle and later stages of production.The matrix permeability is directly proportional to the single well EUR.The production of single wells in horizontal wells and roadways in the Class I reservoirs is significantly higher than that another ones.Ensuring the high drilling rate of a small layer and wellbore integrity results in high production.