Offshore ESP-Selection Criteria: An Industry Study

Abstract

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 146652, ’Offshore ESP-Selection Criteria: An Industry Study,’ by Michael C. Romer, SPE, Mark E. Johnson, SPE, Pat C. Underwood, SPE, and Amanda L. Albers, SPE, ExxonMobil, and Russ M. Bacon, R.M. Bacon Engineering, prepared for the 2012 SPE Deepwater Drilling and Completions Conference, Galveston, Texas, 20-21 June. The paper has not been peer reviewed. Most offshore wells that require artificial lift are gas lifted because gas typically is readily available and, compared with other lift systems, gas lifting is relatively inexpensive and low maintenance. However, electrical submersible pumps (ESPs) can increase oil production and reserves recovery efficiently and economically under the appropriate operating conditions. ESPs can lower the abandonment pressure and, in the long term, possibly reduce the total number of wells required to deplete an asset. Because few ESPs are installed in offshore wells, ESP-screening “rules of thumb” were formed as a simple guide to prioritize offshore ESP candidates. Introduction Pumps typically achieve higher drawdowns than gas lift under appropriate operating conditions. Early in the life of the pump, greater production is achieved with its higher drawdowns. Note that increased production over the long term must be supported by good reservoir management and voidage-replacement practices. Lowering the flowing bottomhole pressure can improve a well’s access to reserves in stratified reservoirs. Pumps also reduce the burden on the gas-compression system and enable selling gas or reallocating it to other gas lift wells. ESPs have a small topside footprint, do not impair subsurface-safety-valve operation, can achieve high production rates, and can aid fluid processing on production facilities because high-pressure power fluid or gas is not required. However, it can be difficult to determine the best ESP candidates when faced with numerous opportunities, limited resources for reserves studies or artificial-lift analyses, and finite installation capital. ESPs can help maximize an asset’s profitability, and screening criteria can streamline the candidate-selection process. These screening criteria were developed for dry-tree offshore applications. The high complexity, cost, and risk involved with subsea ESP installations and workovers typically have limited subsea pumping to seafloor technologies such as subsea separation, multiphase pumps, cartridge ESPs, and caisson ESPs. This trend may change with continued progress in alternative ESP-deployment/-retrieval technologies and/or run-life and reliability improvements.