How Will Subsea-Processing Technologies Enable Deepwater-Field Developments?

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 27661, “How Will Subsea Processing and Pumping Technologies Enable Future Deepwater-Field Developments?,” by Phaneendra B. Kondapi, Texas A&M University, and Y. Doreen Chin, Ashesh Srivastava, and Zuying F. Yang, Subsea Engineering Technologies, prepared for the 2017 Offshore Technology Conference, Houston, 1–4 May. The paper has not been peer reviewed. Copyright 2017 Offshore Technology Conference. Reproduced by permission. This study examines how subsea processing (SSP) can develop into an important enabling technology for future ultradeepwater-field developments and long-distance tiebacks. The authors identify the gaps that need to be closed and describe the decision-making process during the field-development life cycle by considering the technical and economic constraints of various SSP technologies. Introduction A generalized definition of SSP is any active treatment of the produced fluids at or below the seabed to improve recovery factor of reservoirs. SSP technologies include multiphase pumping, subsea separation, gas compression, and raw-seawater injection. Subsea separation coupled with liquid boosting is effective in enabling production at very low flowing tubinghead pressures, even in deep water. This method also is well-suited for use where heavy, viscous oil or low reservoir pressure is the rule. Gas fields often are developed with subsea wells and multiphase transport to onshore facilities or to offshore processing platforms. Separation allows decreasing boosting-power requirements. Subsea-separation technology is progressing quickly because of its huge potential in minimizing topside water-handling requirements and separation of gas, oil, and water from the production fluid. Subsea gas-compression technology is one of the faster-growing technologies for large fields requiring pressure boosting (e.g., where subsea-to-beach development solutions result in long tie-back distances). It improves the production and recovery from the reservoir by reducing backpressure on the wells. As of this writing, more than 25 subsea boosting systems and six major subsea separation systems have been installed or awarded throughout the world. Given the growing number of greenfield and brownfield applications, some analysts anticipate the number of SSP systems installed globally to double by 2020. The complete paper contains a detailed discussion of the development of these technologies, from their origins to their current incarnations. Why SSP? SSP is typically considered for systems with a tieback to a host structure and can influence all phases of project life (start-up, plateau production, late life, and tail end). SSP can consist of the following: Use of single- or multiphase pumping systems to enhance the fluid-driving energy (subsea boosting) Subsea separation and disposal of the produced water (two-phase separation) Subsea separation of oil, gas, and water (three-phase separation)