TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe authors in this paper attempt to propose a model for identifying and selecting key technologies that would add value to the return on investment on a Multilateral well. The last few years have seen the proliferation of Multilateral (ML) wells in the Asia Pacific region and elsewhere in the world. On a parallel front, the oil industry has experienced the introduction of key technologies such as geosteering, rotary steerable "automated" drilling tools, sealed junction technologies, non damaging drill-in fluids, re-entry access completion equipment in development projects worldwide. In conjunction with the development in junction classification and junction construction, it has been noticed that these key technologies in areas of drilling, completion and well planning are increasingly being applied to the construction of Multilateral wells. This paper traces the historical outline of the technology development in Multilateral wells, and it documents the milestone introduction of key technologies that will greatly enhance the return on investment in a Multilateral well. The Authors in this paper will propose a model for identifying the technology needs and the potential enhancement in cost savings for applying key technology. The benefits and cost effectiveness of these technologies are discussed in this paper, and the inevitability of Multi-lateral technology converging with other key technologies are highlighted.

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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Advances in drilling technology are now making possible the drilling and completion of oil and gas wells that just a few years ago would have been inconceivable. Significant advances in downhole tool sensor placement and reliability are aiding operators in optimizing wellbore placement to within a matter of tens of centimetres in the vertical plane. Over and above this lateral well placement in the 3D horizontal plane now make it possible to intersect high permeabily horizons and steer the wellpath in three dimensions to ensure the well is able to maintain its position within the "sweetest zone". In this paper the authors will demonstrate how advanced technology was used to drill the Sotong 5, 6 and 7 trilateral wells using a rotary closed loop drilling system. These types of tools provide enhanced drilling-while-steering efficiency and improved hole quality. It comprises a surface to 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, through the utilisation of reservoir navigation services (geosteering). This eliminates the "wait and see" aspect of drilling with conventional steerable systems, which often results in less than optimal well placement, as well as getting continuously updated models of the placement of the drainhole within the reservoir. This technology is augmented through realtime wellsite information transfer from the rigsite to the office. Therefore the critical well path decisions can be made in real time by the team in the office and implemented at the wellsite instantaneously. The paper will discuss tangible performance metrics and attempt to quantify through statistical analysis the added value of such systems. Introduction The Sotong field is located in Block PM-12 in the southern part of the Malay basin, offshore Peninsular Malaysia. The field, being marginal, was selected to be developed utilizing multilateral technology. An initial economic study indicate that using conventional deviated wells would not be cost effective. The development drilling commenced in July 1998, and Rotary Steerable System was deployed one year later, in June 1999, which was the first application of the system in Malaysia. Futhermore, geosteering technology was utilized to precisely locate the optimum wellbore placement in the target reservoir. Advancement in information technology provides a real-time communication and data transfer between the offshore installation and Petronas Carigali HQ. Technical Objectives The objective was to efficiently drain a marginal reserve using multilateral Level 4 technology. The well paths were precisely placed in an optimal position using rotary steerable systems and geosteering in order to ensure optimum production and field life.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe authors in this paper attempt to propose a model for identifying and selecting key technologies that would add value to the return on investment on a Multilateral well. The last few years have seen the proliferation of Multilateral (ML) wells in the Asia Pacific region and elsewhere in the world. On a parallel front, the oil industry has experienced the introduction of key technologies such as geosteering, rotary steerable "automated" drilling tools, sealed junction technologies, non damaging drill-in fluids, re-entry access completion equipment in development projects worldwide. In conjunction with the development in junction classification and junction construction, it has been noticed that these key technologies in areas of drilling, completion and well planning are increasingly being applied to the construction of Multilateral wells. This paper traces the historical outline of the technology development in Multilateral wells, and it documents the milestone introduction of key technologies that will greatly enhance the return on investment in a Multilateral well. The Authors in this paper will propose a model for identifying the technology needs and the potential enhancement in cost savings for applying key technology. The benefits and cost effectiveness of these technologies are discussed in this paper, and the inevitability of Multi-lateral technology converging with other key technologies are highlighted.