5. Basin, Low-permeability Gas Condensate Reservoirs Damage Factors On Gas Well Productivity Impact Study

The low permeability condensate gas reservoir is a special reservoir with the characteristics of the low permeability and the trait of gas condensate reservoir. So performing a study on the factors and variation law of the gas well's production for low permeability condensate gas reservoirs not only can help us to understand the development law of low permeability condensate gas reservoir, but also its results are of highly theoretical meaning and applied value.P5 gas reservoir is a low permeability condensate gas reservoir with "upper gas, medium oil, and lower water", heterogeneous, with asymmetric distribution, with formation having certain sensitivity and bad communication between wells, with relatively strong heterogeneity. In the development process, various behaviors will have a heavy impact on productivity of gas well and production performance, such as formation stress sensitivity, condensate oil contamination and bottom water encroachment, etc. For this special phenomenon of the low permeability condensate gas reservoir P5, this paper carries out the following study based on the analysis and evaluation of geological characteristics of P5 gas reservoir, by combining the experiments with theory research and numerical simulation method, finally obtaining the corresponding results.(1) Using various static geological test data provided by field and the dynamic materials of well test, production test and production data, geological characteristics of P5 gas reservoir is evaluated and production performance of all single wells is analyzed and studied.(2) Using the core and fluid information of P5 gas reservoir acquired, formation damage evaluation experiments are done, confirming that the main influence factors are stress sensitivity, condensate oil contamination.(3) The variation law of gas well productivity under stress sensitivity is analyzed, the distribution of condensate oil near the wellbore is researched through numerical simulation approach, and the equation of gas well rate while considering the condensate oil contamination is built.(4) The equation of gas well rate while comprehensively considering stress sensitivity and condensate oil contamination is constructed, and then according to the Field situation, the additional skin causing by black oil influx is studied, the equation mentioned above is further built and the productivity variation law of the non-producing black oil, producing black oil and horizontal gas well is analyzed.