Offshore Installation and Maintenance of Submersible Pumps

Abstract

Verdina, G.G., SPE, IIAPCO Div. of Natomas Intl. Corp. Summary Pertamina/IIAPCO operates a large offshore production Pertamina/IIAPCO operates a large offshore production complex in the Southeast Sumatra Contract Area of Indonesia. The use of submersible centrifugal electric pumps both for artificial lift and for pipeline transfer of pumps both for artificial lift and for pipeline transfer of produced fluids has played an important role in the produced fluids has played an important role in the success enjoyed by this contract area during its 10-year producing life. This paper describes the conditions and producing life. This paper describes the conditions and considerations contributing to the initial selection and eventual standardized use of these pumps by the company. Also included are a discussion of operational experience gained and a summary of the submersible pumps performance record. performance record Introduction The operational area of the company lies in a region of the Java Sea roughly bounded by the southeastern shore of Sumatra on the west and by the string of islets known as the Pulau Seribu, or Thousand Islands, on the east (Fig. 1). In this area of relatively shallow. normally calm waters, the company over a period of 10 years has built a production/process/export facilities complex, which to production/process/export facilities complex, which to date consists of 33 platforms in 9 fields over a north-to- south distance of 30 miles (Fig. 2). Although the first wells initially were produced by natural flow. Early rapid decline in bottom hole pressures (BHP's) and production rates soon indicated the need for artificial lift. Downhole submersible pumps were introduced into the system, and eventually became an integral and standard part of all Southeast Sumatra Contract Area well completions. As of Nov. 1, 1981, 167 pumps were in service in the contract area, making this pumps were in service in the contract area, making this operation one of the largest offshore applications of its kind. Facilities Overview Produced fluids in the contract area are conveyed by Produced fluids in the contract area are conveyed by means of three-phase flow through insulated subsea pipelines from remote production satellite platforms to a pipelines from remote production satellite platforms to a central treating complex located in the Cinta field. The treatment facilities provide for gas/oil/water separation and deliver crude to a 1,000,000-bbl barge for storage and terminal export. The typical production platform in the contract area is a nine-slot, four-pile, steel template structure (Fig. 3). The platform deck is engineered to accommodate a production manifold, a well test separator, electrical production manifold, a well test separator, electrical switchgear for the submersible pumps, a hydraulic unit for the downhole safety valve system, and an emergency generator set. Power for the submersible pumps is supplied to the platform through submarine cables from the generating plant located at the central complex. Rationale for Use of Submersible Pumps The early production history of the first, naturally flowing, wells in the Cinta field indicated the need for a method of artificial lift to cope with increasingly large volumes of water and rapidly declining BHP'S. Since sufficient gas was not available for gas lifting, submersible pumps were selected on the basis ofestablished repair and replacement service facilities in the general area andlimited space requirements for pump ancillaries on the platforms. Installation of these pumps on initial completion offered the additional advantage of controlling production from the on set. thus eliminating the later need to pull completion strings and install pumps once BHP's had dropped and/or water cuts had become excessive. As the facilities complex expanded and additional remote satellite platforms were installed, the use of submersible pumps became even ignore important. Submersible pumps then became the standard mechanism for assisting fluid transmission through pipelines. In other words, a pump installed in a given pipelines. In other words, a pump installed in a given well would be designed to develop sufficient head not only to lift fluids to the surface, but also to deliver these fluids by three-phase flow to process facilities several miles away. JPT p. 222