There are now a variety of ways to achieve higher recovery factors from heavy oil reservoirs, but most of them involve the injection of thermal energy or chemicals to reduce the oil viscosity. While these techniques have been highly successful, they can also be very expensive when the steam generation and/or chemical injection costs are accumulated throughout the productive life of the field. A lower cost solution, one that has been very successful in the Faja Del Orinoco of Eastern Venezuela, is to use multi-branched wells (multilaterals) to increase reservoir exposure and achieve an arguably higher recovery factor. These multilateral wells have been shown to produce more oil over a longer period of time than conventional horizontal wells without any additional operating costs. This paper will discuss the concept of using multilateral wells as an alternative to conventional Enhanced Oil Recovery (EOR) techniques in heavy oil reservoirs. It will argue that the oil recovery factor of a reservoir that is drilled with increased wellbore exposure can be comparable to thermal/chemical EOR under the right circumstances, and that the project will have a much lower operating cost. While steam injection has become the successful mainstay of most EOR projects, there are many drawbacks such as the costs of the steam generation and the emission of greenhouse gases. Multilateral wells can potentially offer an option to produce the same reservoir with lower costs while still recovering an increased percentage of the oil from the reservoir. This technique is especially applicable in inter-bedded or thin oil zones where steam injection would be costly and inefficient. Extensive background information will be presented from the Orinoco belt in Venezuela, where multilateral wells have proven to be an economical approach to develop a very challenging "extra-heavy" oil reservoir. The Petrozuata Project The Petrozuata project is a joint venture between ConocoPhillips (50.1%) and PDVSA (49.9%), to produce, upgrade, and commercialize extra heavy crude oil from the San Diego field, which is located in the Zuata region of the Orinoco Belt in eastern Venezuela. The joint venture operates under a 35-year production contract. Early blend production began in 1998 and the commercial sales of upgraded (synthetic) crude began in 2001. In 2004, Petrozuata achieved record volumes, producing more than in any year since its start-up in 1998. This increase was largely the result of extensive use of advanced drainage architecture and multilateral wells. The main oil reservoir in the ¨Faja del Orinoco¨ are the Miocene sands of the Oficina formation. In the Petrozuata area, the reservoir is described as aggrading coastal plain deposits consisting primarily of massive multistoried and/or stacked, coarse-to-fine-grained fluvial channel belts prograding from south to north. The sands are poorly- to well-sorted and unconsolidated. They have net-to-gross sand ratios of approximately 55 to 65%. Within the primary oil reservoir, the permeability ranges from 700 to 15,000 millidarcies (mD). The channel morphologies vary from highly sinuous silt-filled, laterally stacked to straighter, braided channels. The channel sands are typically 20 to 40 feet thick and as wide as 1 to 2 kilometers (3000 to 6000 feet). By their nature, they tend to be laterally discontinuous and contain a certain percentage of silts (non-reservoirs) within the channel complexes. To achieve high performance wells, the percentage of high-quality oil sand contacted along the horizontal well length must be maximized. Careful geological planning and well design can allow several disconnected sand units to be produced from a single well. Such provisions greatly improve oil recovery and increase well production. To do so, however, requires the strategic placement of horizontal sidetracks and multilateral junctions. Reservoirs range in depth from 1700 to 2500 ft TVD, with average temperatures of 120 to 125ºF. The oil gravity lies between 8.5° and 9.5º API, a range that qualifies the oil as "extra-heavy." The reservoir itself is a low pressure, viscous fluid environment that requires significant physical encouragement to get the thick oil to flow. "Drain" is actually a more appropriate term than "flow" because the wells are drilled so closely together and with such frequency that the oil is essentially drained from the sand, under the force of gravity, into wellbore tubulars from which it can be pumped to the surface.

Multilateral wells offer many benefits over conventional wells, including reduced overall drilling costs, lower environmental effect, increased total recovery, greater access to production intervals, and subsequently improved well production rates. However, it can be difficult to achieve a good quality casing window through which an additional lateral branch can be successfully drilled and completed. As bottomhole assemblies (BHAs) become more advanced, involving longer and stiffer strings of tools, and as completion design becomes more intricate, more attention must be given to the way the casing window is created because this is the foundation of multilateral well design. Track-guided milling systems have emerged as effective and accurate methods by which to control casing window geometry, and this paper will focus on recent advances in track-guided, precision window milling technology and its effect on multilateral well design. To avoid potential problems in running drilling assemblies or liner/completion strings, advanced milling technology should be used to create the casing window. During conventional milling, it is commonly difficult to control the action of the mill as it cuts through the casing; poor control creates a casing window that could, as a result of right hand rotation during milling, rolling-off to one side, leading to a skewed or shortened aperture. Uncontrolled and undefined window geometry introduces additional risks when re-entering a lateral wellbore, such as nonproductive time (NPT) and equipment damage. A good quality casing window, with precisely controlled length and width, helps ensure that drilling and completion equipment can exit the aperture without problems and facilitates repeatable re-entry access to both the mainbore and the laterals in future interventions. The quality of the casing window is just as critical in multilateral wells as in conventional sidetracking or whipstock operations. Advances in modern casing milling technology are pioneering improved multilateral well designs. Multilateral wellbore junctions can now be placed in deep, high-angle wells without compromising drilling or completion operations by using a track-guided milling system to create improved casing windows.

The production of both fines and matrix sand into the well bore is a common problem in water injection wells due to transient pressure and flow events. Conventional sand control techniques do not manage these transient events effectively, and the reliability of the sand control can be compromised as a result. In injection wells, a shutdown event results in a sudden stoppage of flow causing a surge which can result in powerful downhole pressure transient effects such as back-flow, cross-flow, and water-hammer. These effects can mobilize sand particles in the near-wellbore resulting in an influx of fine particles, screen plugging and erosion. Eventually, the accumulation of debris in the well can lower or block injection rates to the point where a water injector well must be repaired or replaced to maintain the injection volumes required for pressure maintenance and sweep in the reservoir. A new, sand screen compatible completion was designed with an array of integral non-return valves (NRV) to address these challenges. This paper will present an overview of the product development with computation fluid dynamics (CFD) modeling, flow-loop and laboratory testing. Design considerations of any potential adverse effects of the new non-return valves, such as plugging and erosion, were studied extensively in lab tests on a series of valve designs. Non-return valve completions could have the benefit of increasing injection volumes and extending the life-cycle of water injections wells.

Advanced smart multilateral wells with extended reservoir contact from a single well location have accelerated sustained oil production and increases hydrocarbon recovery from ultra-high water mobility oil-wet Burgan reservoir in Minagish Field West Kuwait. Further the smart multilateral wells have proven to be a great tool for adequate proactive reservoir management and production management without well interventions. The Burgan reservoir has active aquifer, very high permeability sands associated with active faults and contain highly viscous reservoir fluid with downhole viscosity of more than 40cp, enhance water mobility and resulted in premature water breakthrough with increasing water cut trend within few months of production in existing horizontal wells. This has resulted into non-uniform reservoir depletion, by-passed oil regions and low oil recovery. The smart level-4 multilateral wells were successfully designed and implemented in Burgan reservoir by combining the reliable Level-4 junction along with stacked dual lateral completion having customized viscosity independent Inflow Control Device (ICD), customized two Inflow-Control Valves as well as down hole gauges, wide operating range Electrical Submersible Pump (ESP), suitable wellheads, X-MAS tree and Integrated surface panel for real time data monitoring first time in Kuwait. The improved production performance of smart multilateral wells in Burgan reservoir of Minagish Field, West Kuwait have achieved appropriate production management through flow regulations across laterals and adequate reservoir management with the combination of inflow control device as well as inflow control valves along with downhole pressure temperature gauges. Moreover the smart multilateral wells have enhanced sustained oil production, maximizes hydrocarbon recovery at lowered capital and operational expenditure resulted in improved economic performance of reservoir with significant increase in net present value (NPV). The paper covers the successful implementation of smart multilateral wells and its effectiveness in achieving the life-cycle production management as well as proactive reservoir management supported with actual well performance results. Further the paper details about the economic benefits of smart multilateral wells and its contribution in improving the economic performance of Burgan reservoir of Minagish Field, West Kuwait.

Increased hydrocarbon recovery and accelerated production from ultra-high water mobility oil-wet reservoir requires the application of advanced well completion technologies to address premature water breakthrough, reservoir management, production management and extended reservoir contact from a single well location. The Burgan Reservoir of Minagish Field, West Kuwait has active aquifer, very high permeability sands associated with active faults and contain highly viscous reservoir fluid with downhole viscosity of 40cp, enhances water mobility and resulted in premature water breakthrough with increasing water cut trend within few months of production as confirmed from well performance of existing horizontal wells. This has resulted in to non-uniform reservoir depletion, by-passed oil regions and low oil recovery.The Kuwait's first smart level-4 multilateral well was completed in Burgan reservoir by combining the Level-4 junction along with stacked dual lateral completion having customized viscosity independent Inflow Control Device (ICD), customized two Inflow-Control Valves as well as down hole gauges, wide operating range Electrical Submersible Pump (ESP), suitable wellheads, X-MAS tree and Integrated surface panel for real time data monitoring. The smart multilateral well has assisted in addressing premature water breakthrough, enhanced dry oil production and facilitated uniform depletion, which results in improved hydrocarbon recovery. The paper covers the customized design of smart Level-4 multilateral well by taking in to account the reservoir and its fluid characterization, well architecture, implementation and specially designed invert emulsion drilling fluid for effective wellbore cleanup to achieve formation virginity. The improved reservoir management and production management results are also mentioned in this paper.