Successful Scale Mitigation Strategies in Saudi Arabian Oil Fields

Abstract

Abstract Scale deposition, either in the formation or in the production facilities, is a challenging problem in the petroleum industry. Scale mitigation and prevention programs are critical for sustained oil production. It is therefore essential to put in place proper scale management strategies before developing a new field. In addition, exploring new chemical formulations and treatment strategies for current field programs should be examined on a continuous basis to ensure efficient results are achieved. Saudi Arabian reservoirs have their own set of scale related challenges. Calcium carbonate scales were a major challenge in a majority of wet producers in several carbonate reservoirs across Saudi Arabia. The possibility of a sulfate scaling problem in these fields was minimized by selecting compatible floodwaters and/or creating a sufficient buffer-band to separate the incompatible waters. Phosphonate based scale inhibitor treatments, either encapsulated chemical applied in the rathole or squeezed into the formation, have been highly successful. This has been attributed to the relatively low scaling potentials and associated low threshold inhibitor concentrations, an effective sampling and monitoring strategy and a proactive approach to managing the scaling problem. Over recent years, well architecture has become more complex, requiring innovative scale mitigation strategies. Vertical wells have been replaced with horizontal wells, horizontal wells with multilaterals, and multilaterals with maximum reservoir contact wells. The future wells include extreme reservoir contact and it is imperative to develop viable and cost-effective treatments for this variety of well types. This paper details how Saudi Aramco mitigated difficult to handle sulfate scaling problems with proper selection of floodwaters in various fields, describes the theoretical background in selecting simple and inexpensive bullhead scale inhibitor squeeze treatments for horizontal wells. We also present technical and economic reasoning for the successful scale management strategy in Saudi Aramco fields with case histories.