No abstract

As giant oil fields mature, the flow of results from development drilling and production history, as well as interpretations of new seismic data, provide an evolving view of in-place volumes, reservoir architecture and fluid movement through the reservoir. Often, such changes can trigger modifications to asset development plans and, together with economic conditions, revisions to estimates of ultimate recovery.The development of the Alba Field – a relatively heavy oil (19° API) accumulation lying in an Eocene deep-water channel complex in Block 16/26 of the UK's Central North Sea – has followed a similar pattern. With an estimated 900 mmbbl of oil in place, the reservoir is characterized by thick, high net-to-gross (NTG) sands with extremely favourable reservoir properties. Because of the less favourable mobility ratio, Alba has been developed exclusively by horizontal production wells, with pressure support provided by a series of seawater injectors.By mid-2012, after 18 years of production, more than 390 mmbbl of oil had been recovered. During production, several key seismic and drilling technologies were applied to address reservoir complexities and reservoir management concerns that emerged as field development progressed. The most significant of these include the following: a dramatic uplift in imaging the depositional architecture was provided by converted shear wave seismic data (1998), revealing an extremely irregular top reservoir and hinting at greater internal complexity than initially modelled;advances in extended reach drilling technology enabled a greater number of infill targets to be accessed, while geosteering techniques allowed better well placement, and horizontal completions using gravel packs improved well reliability;spectacular images of production cones beneath horizontal production wells extracted from a dedicated 4D monitor survey (2008) addressed the field's key dynamic uncertainty – where is the remaining oil?A challenge for Alba has been to fully understand a 4D seismic signal that originates from long horizontal producers where vertical rather than lateral sweep dominates. Ultimately, reliable reservoir models that capture these valuable dynamic insights, based on geologically reasonable interpretations, will be the key tool that enables bypassed oil to be targeted and recovered, as fields such as Alba advance towards their development vision.

Minimizing fresh raw water and wastewater effluent produced by industry has rigorously been studied over the past two to three decades. However, most studies have focused on rather theoretical illustration with little consideration of technical constraints in industry. Furthermore, use of massive industry data significantly increases the complexity of the problem, and no research paper has covered such a case study with practical solutions. This paper reviews the latest technology of water network synthesis and its applications, and provides a detailed guideline of the whole study procedure with a reference to case study based from refinery complex. Two main methodologies of waterpinch technology and a mathematical optimization programming are reviewed individually, and they are applied to a case study. Economic and operational constraints are embedded into optimization of water network synthesis in order to provide more reliable and achievable solutions for the minimization of fresh water consumption and reduction of waste water effluents. This generic approach can be similarly applied to other industries such as petroleum, steel, and paper manufacturing.

The Alba Field is a relatively heavy oil accumulation lying in an Eocene deep-water channel complex in Block 16/26a of the Central North Sea. With an estimated 880 MMbbl in place, the reservoir is characterized by thick, high net/gross sands with excellent reservoir properties and rock physics favourable for seismic property detection. The field has been developed by horizontal production wells, with pressure support provided by seawater injectors. After 24 years of production, more than 427 MMbbl have been recovered.Over the course of the development, the results of development drilling and improved reservoir imaging from seismic have revealed greater reservoir complexity than anticipated at sanction. The highly irregular reservoir geometry is likely to reflect the internal stacking patterns of channel elements within the channel complex that are locally overprinted by post-depositional remobilization. This increased reservoir complexity has required more wells to effectively drain the expected volumes. Despite this, recovery has exceeded estimates from the initial field development plan, reflecting an extremely efficient waterflood. 4D seismic spectacularly images extensive sweep away from injectors and excellent reservoir connectivity. Throughout the development, the application of seismic technologies has been a key enabler for effective reservoir management and, looking forward, maximizing value.