Preliminary study on the recognition of flowback characteristics after exploration and evaluation of ultra-deep oil and gas Wells

Abstract The oil and gas reservoirs in the Tarim Basin are generally buried deep, and more than 90% of the oil and gas wells are ultra-deep wells. The oil testing and completion operations of ultra-deep wells have four major characteristics: “high”, “deep”, “connected” and “complex”. At the same time, the operation risks are high, the well construction cycle is long, the natural productivity is low, and the stable production is difficult. More than 70% of the wells require reservoir transformation. The blowout production cycle after the transformation is long. The return flow data obtained at the cost of huge time and money fails to provide sufficient information for subsequent production guidance. This paper proposes a method for studying the characteristics of reservoir return flow based on the analysis of blowout production data. Two new parameters, the decline ratio and the return flow ratio, are defined. The return flow ratio versus decline ratio curve can be used to analyze reservoir physical properties and heterogeneity, and can be used to effectively predict formation water production in combination with the water property data of the return flow fluid. This method improves the utilization rate of return flow data, can help guide the subsequent blowout production process, shorten the time for blowout production, save time and money, and improve the efficiency of oil testing operations.