This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 29407, “Why Not Boosting? Uncover the True Value of Your Subsea Asset,” by Morten Stenhaug, SPE, Hongkun Dong, and Mads Hjelmeland, Schlumberger OneSubsea, prepared for the 2019 Offshore Technology Conference, Houston, 6–9•May. The paper has not been peer reviewed. Copyright 2019 Offshore Technology Conference. Reproduced by permission.
The first subsea multiphase boosting system was installed in•1994. Since•then, it has grown into a•technology with a global track record.•This paper is aimed at identifying potentially significant hidden•value of the technology, or aspects thereof that have•not received adequate attention during the field-development decision-making process.•The authors demonstrate that a more-complete and -integrated assessment approach can reveal this additional value.
The effect of boosting on increased recovery is realized through lowering of the wellhead, bottomhole, or reservoir pressure at which hydrocarbons can be produced economically. This translates into a higher degree of reservoir depletion; more-efficient drainage; and, to a certain extent, greater volumes produced.
Increased oil recovery (IOR) has been the primary driver for adding artificial lift to subsea production systems, and also for subsea multiphase boosting. In projects in which subsea multiphase boosting was selected, IOR was the main driver for more than 90% of the assets.
A review of field-development projects over the past 30 years for cases in which boosting was evaluated but not chosen revealed that many had used fixed production profiles or decline curves that were developed originally for either natural flow or gas-lifted flow (i.e., with a fixed total producible volume). These approaches do not permit quantification of improved recovery. Another observation is that these shortcuts to artificial-lift evaluation in the early project development phase tend to be carried through the subsequent decision gates of a project without being challenged.
Another aspect of the technology that is often neglected is the fact that the actual cost of the additional barrels of oil enabled by subsea multiphase boosting can be significantly lower compared with the cost of a barrel of oil from regular field development. Furthermore, for larger fields with higher recoverable volumes, or a higher recovery factor, the full-cycle capital expenditure (CAPEX) may be reduced to less than $5/bbl.
Benefits of Subsea
Multiphase Boosting Accelerated Production. The financial effect of accelerated production is a less-used evaluation criteria with regard to subsea multiphase boosting. There are reports in the literature of flow-rate increases of 20 to 100% online, with this early revenue leading to improved net present value, internal rate of return, reduced payback time, and lower breakeven price—factors that are often not considered.