Integrated Well Test Interpretation Approach for Complicated Carbonate Reservoirs: A Field Case

The main characteristic of the complicated carbonate reservoirs is notably strong heterogeneity, leading to a high uncertainty in formation parameter evaluation [1,2]. In general, logging, core analysis and pressure transient analysis (PTA) are used to evaluate the reservoir parameters of carbonate rocks. However, core and logging analysis can be used to get static parameters in the range of centimeter to meter, while PTA can obtain static and dynamic parameters in the range of hundreds of meters to several kilometers, such as skin coefficient, boundary conditions, permeability and cross flow coefficient. Therefore, the PTA results are more practical and reliable. However, the well test curve shows similar characteristics for multi-layers reservoirs, dual-medium reservoirs, and carbonate reservoirs with lithology mixed sedimentation lithology [3,4]. It is important to reduce the parameter evaluation multiplicity. However, many scholars did not consider the multiplicity of PTA interpretation in practical application, which led to large errors in the results [5,7]. Therefore, this paper comprehensively summarizes all the reasons leading to the depression of pressure derivative curve, and puts forward the corresponding identification approach, which has been applied in Abu Ghirab reservoir well test interpretation and created conditions for improving the accuracy of PTA.