Production Water Management

Abstract

R.W. Hintermaier, SPE, Saudi Arabian Oil Company (Saudi Aramco) Abstract Since 1979, water produced from Saudi Aramco's largest field, Ghawar, has continually increased. Water management is multi-faceted, with development drilling locations in water-free areas, subsurface water shut-off workovers, and water handling facility expansion. Beginning with a brief historical summary, this paper describes the overall program. A successful team approach, the engineering methodology used to assess needs and develop plans, and surface facility evolution during the last five years, are emphasized. Augmented separation capacity, de-bottlenecking of piping, increased pumping capacity, and additional disposal wells have been added to surface facilities. Examples of typical projects are presented. Development drilling and water shutoff work are briefly discussed. Future plans to ensure that adequate capacity is continuously available are also described. Introduction Ghawar Field is located nw the western edge of the Arabian Gulf. The field is formed by a structural entrapment of oil along a major anticline, the "En Nala Axis." Production is primarily from the Arab-D reservoir. The field is under peripheral injection waterflood Water injection distribution on the periphery varies with withdrawals. Water sources are primarily seawater from the Arabian Gulf, and re-injected produced water. Produced water and seawater are injected through separate systems. Produced fluid is processed through Gas Oil Separation Plants (GOSPs). Before 1979, GOSPs were not equipped with Wet Crude Handling Facilities (WCHF's) and wells which produced water were shut-in. Routine water production began in 1979, with the completion of the first WCHF's. Fig. 1 is a process flow diagram for a typical GOSP. From the manifold, emulsion flows through a three-phase High Pressure Production Trap (HPPT), a two-phase Low Pressure Production Trap (LPPT), and on to the WCHF's. WCHF's consist of dehydrator and desalter vessels, wash water supply facilities, water/oil separators (WOSEPs), salt water disposal (SWD) pumps, piping and disposal wells. Saudi Aramco is organized by function. Operations, Maintenance, Operations Engineering, Production Engineering Future Oil Development, Reservoir Engineering, Project Management Teams, and other groups report to different functional management. Consensus is required to solve multi-functional problems. Situation in 1992, Team Formation, and Work Distribution By late 1992, concern began to develop about handling water production in a more mature part of Ghawar field. At the time, forecasts showed that certain GOSPs were predicted to exceed WCHF dehydrator/desalter nominal capacity within a year. Cerin facilities would exceed installed pump capacity, and some would closely approach it. Action was required to avoid future production losses resulting from inability to handle water production. A preliminary evaluation by Operations Engineering, Production Engineering, and Future Oil Development, estimated that major expenditures would be required for expansion of water handling facilities in the next five years. Development and implementation of recommendations to deal with the shared problem required close cooperation between, and consensus of, various functional groups. P. 481^