The practical application of new technologies, including rotary steerable drilling systems are overcoming previous limitations in directional drilling to make designer, multilateral and extended reach wells easier to drill. In this paper, the authors will discuss the tremendous value that can be achieved through application of winning technology and teamwork that has been proven as an effective tool in maximizing business opportunity in Asia Pacific. Multilateral wells offer tremendous advantages including reducing the size of platforms, surface locations, subsea completions and total wells required to fully exploit a hydrocarbon reservoir. However, such complex 3 dimensional well applications can be severely limited by a number of factors including:Prohibitive well costsRig sizing considerationsLess than optimal directional controlTorque and dragUnreliable WOB transfer and poor hole cleaningEnvironmental considerations. One technology having a significant impact on such designer well applications are rotary closed loop drilling systems. These systems provide enhanced drilling-while-steering efficiency and improved hole quality. It comprises a non-rotating steering unit, a downhole guidance system, formation evaluation (with optional LWD) and downhole pressure monitoring. These tools can automatically guide the bit to a preprogrammed target and two-way surface communication allows rigsite engineers to adjust the well trajectory to meet drilling objectives and redirect the wellpath based on real-time formation logs. This eliminates the " wait and see" aspect of drilling which often results in less than optimal well placement, unnecessarily complicating the forward directional plan for the well or missing the target all together. In 1998 Petronas Carigali Sdn. Bhd. commenced the Sotong field development in offshore Peninsular Malaysia. The objective was to efficiently drain marginal reserves using multilateral Level 4 technology. The wellpaths are precisely placed in an optimal position using rotary steerable technology in order to ensure maximum production life of well. Modern communications systems has allowed this technology to transfer real-time wellsite data from rigsite to shore. The critical well path decisions can be made in real time by the team in the office and relayed to the wellsite instantaneously and changes can therefore be made immediately. Technical Objectives Sotong is a marginal field that could only be economically developed through utilization of multilateral technology. Once drilling had commenced it was determined that this would be a suitable application for RSS technology. The main technical objective was the effective drainage of the K2 reservoir. Reservoir Description The main reservoir on Sotong field is K2 sandstone. This is a 32m thick sand (2166m - 2198m TVD SS) which has an oil column of 14m. This is bounded by a large gas cap above and water below. Hence, the reservoir objective was to place well path 2m above the water contact. This location is chosen in order to optimize productivity. TVD control with high precision within a 0.5m tolerance was used to define the exact location of the OWC throughout the reservoir. Anticipated problems in well path control due to hard dolomitic stringers within the reservoir were overcame.

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