Low Pressure Operation LPO: Extending Field Life of Several High H2S Fields with Minimum Costs

Abstract

Abstract Several high pressure (up to 1000 bar), deep (3-5 km) and high sour oil (H2S/CO2 up to 10%/25%) fields have been in primary depletion production in the Southern Sour Cluster in Petroleum Development Oman (PDO) for the last several years. These fields are currently nearing lift-die out or have already experienced lift die out. These carbonate (and silycillite) fields form stringers which are encapsulated by salt and thus lack natural aquifer support. The only drive mechanism has been up to now fluid (and rock) expansion. Artificial lift in form of high cost Electrical Submersible Pumps (ESPs) was attempted in 3 wells and failed due to suspected design and installation issues, including depth of the reservoir. To extend the depletion production life a Low Pressure Operation (LPO) has been proposed across all the 3 stations within the cluster and all currently being executed. LPO makes smart and sustainable use of existing facilities by simply re-routing incoming trunk line in three stations to the low pressure separator. Several other options were screened but were found to be less attractive. LPO will allow continuation of depletion production for several years until Miscible Gas Injection (MGI) is implemented as a next development phase. LPO concept is commercially extremely attractive with very low Unit Technical Costs (UTCs) of less than $10/bbls and high Value Investment Ratio (VIR) of more than 20.