Evaluation and optimization on the well completion technology of combined testing and perforating in Dina 2 Gasfield

Combined testing and perforating technology is advantageous for it can diminish tripping operation, reduce reservoir damage and improve oil and gas well construction efficiency.The well completion technology of combined logging and perforating without releasing the gun was commonly used in the early stage of productivity construction in Dina 2 Gas Field.After its commissioning, however, some problems occurred gradually, such as wellbore plugging and restricted downhole performance monitoring, so it is necessary to evaluate and optimize this technology.Investigation and statistics show that the abnormal phenomenon of sharp tubing pressure drop appears in 75% of production wells which are completed by means of combined logging and perforating technology in the early stage of productivity construction.This abnormal tubing pressure was analyzed based on gas reservoir engineering theories and workover practices.And it is indicated that its essential cause is that the holes of production screens (i.e., holed tubing) at the end of combined testing and perforating string are blocked due to plugging agent flowback and formation sand production.To solve this problem, perforating and testing is carried out by stages in the middle and late period of productivity construction.Consequently, thephenomenon of wellbore plugging is reduced, and it is favorable for the implementation of production performance monitoring.The application of this optimized well completion technology in Dina 2 Gas Field can be used as the reference for similar gas fields.Before the well completion technology of combined testing and perforating, it is necessary to carry out sufficient adaptability evaluation and specific modification and optimization.