In recent years, the oil and gas perforating industry has seen the growth of perforating flow laboratories to develop shaped charges for reservoir-specific conditions. Flow laboratories can help measure perforation tunnel characteristics, flow features, productivity and the performance of shaped charges. Such information is critical to perforating job design, particularly in challenging deepwater wells.
In this study, we are focused on a deepwater subsea sandstone field (1000-1700m water depth) in offshore Africa. The fields typically consist of sinuous turbidite sandstone channel systems of Turonian age. The wells are completed as cased and perforated completions with no active sand control. Typically, deepwater cased and cemented completions are frac-packed, which reduces reliance on perforating performance for efficient flow path from the reservoir into the wellbore. The completion design in this case relies heavily on effective perforations for an efficient flow path, including perforating past drilling damage and minimizing the risk of sand production through selective perforating and reduced shot density.
The formation properties were evaluated to select an analogous rock for implementing a comprehensive testing program. In the first phase, a series of API RP19-B Section IV tests were conducted using various shaped charges to obtain a baseline understanding of shaped charge performance. The rock was stressed to simulate reservoir conditions of overburden, reservoir and wellbore pressures. The testing program aimed at selecting an optimal shaped charge and ensuring the maximum clean up/productivity that can be achieved based on the underbalance method. In addition, the test results provided insight into tunnel geometry, inflow performance and dynamic pressure data to develop an informed perforating strategy. Subsequently, the second phase of the program evaluated the effects of mud invasion on perforation geometry and the higher magnitude of static underbalance on perforation cleanup. This study demonstrates how the perforating flow laboratory can be utilized to design perforating jobs in a deepwater environment. The flow laboratory serves as a unique tool to measure and optimize shaped charge performance in a wide variety of downhole scenarios.
