TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractMultilateral technology offers the oilfield many advantages since it can deploy a completion system that can mechanically connect several lateral wellbores to a parent wellbore and will allow selective or commingled production. In most cases, these capabilities can provide more cost-effective well construction since reservoir exposure from one wellbore is increased. These advantages are particularly beneficial in offshore and deepwater environments where slot and/or subsea templates are limited, and rig costs are substantially higher. Because of the flexibility of this technique and its capability to offer various production options, it helps to mitigate the risks previously associated with directional/horizontal wells in new field developments as well as in revitalization of mature fields. Because of continual improvement in drilling techniques and the increase in field success, multilateral technology continues to gain in popularity; however, as with all completion techniques, it must be remembered that existing completion options must be evaluated for each case, and if needed, adapted to meet specific reservoir objectives and concerns. This paper will focus on considerations, applications, and benefits of specific tool configurations developed for interfacing sand-control fracturing stimulation with multilateral technology. The techniques discussed include existing, modified, and conceptual completion methods that can be deployed into multilateral field-development strategies. The strategies address window selection, junction isolation, fluid loss, debris management, and lateral accessibility. Several completion sequences, which include a new Technology Advancement for Multi-Lateral (TAML) level 4 single-trip, gravel-pack methods and installation of expandable screen technology, will also be presented.

fax 01-972-952-9435. AbstractMultilateral drilling technology has been used in many heavy-

fax 01-972-952-9435. AbstractMultilateral drilling technology has been used in many heavy-

Multilateral technology offers the oilfield a completion system that mechanically connects one or more lateral wellbores to a parent wellbore and allows selective or commingled production. These capabilities usually provide more costeffective well construction since reservoir exposure from one wellbore is increased. In offshore and deepwater environments where slot and/or sub-sea templates are limited and rig costs substantially higher, these advantages are even more beneficial. Because of the flexibility of this technique and its capability to offer various production options, it helps to mitigate the risks previously associated with directional/horizontal wells in new field developments as well as in revitalization of mature fields. Continual improvement in drilling techniques and the increase in the number of field successes using multilateral technology have continued to increase its popularity; however, as with all completion techniques, it must be remembered that existing completion options must be evaluated for each case, and if needed, adapted to meet specific reservoir objectives and concerns. This paper will focus on interfacing sand-control fracturing stimulation with multilateral technology. The techniques targeted include existing, modified, and conceptual completion methods that can be deployed into multilateral field-development strategies. The strategies address window selection, junction isolation, fluid loss, debris management, and lateral accessibility considerations along with the applications, and benefits of specific tool configurations recently developed. Several completion sequences, which include a new Technology Advancement for Multi-Lateral (TAML) level 4 single-trip, gravel-pack methods and installation of expandable screen technology, will also be presented. Introduction The benefits of multilateral technology have been well documented around the world as a cost effective alternative to accessing oil and gas reserves. To date, the bulk of these installations have occurred in naturally fractured carbonate reservoirs as well as poorly consolidated sandstone reservoirs. In either scenario, the lateral borehole typically is drilled horizontally so that maximum reservoir exposure can be obtained. Slotted liners or sand screen completions have been very effective for borehole support and/or sand-control devices when deployed in uniform sandstone reservoirs,1 whereas openhole completions are commonly used in carbonate reservoirs with natural fractures. Fracture stimulation and advanced sand control completion applications can also be implemented into multilateral well planning strategies. Low-perm carbonate reservoirs can be effectively stimulated using traditional stimulation designs normally performed in single wellbore applications. The junction isolation tool configuration will vary and depend predominately on the TAML classification of the junction as well as whether the stimulation job is pumped down the casing or the tubing work string. In addition to isolating the junction from the stimulation-treating pressure, the tool configuration should also have capability to provide well control and zonal isolation. This will allow multiple lateral legs to be individually stimulated from a single parent bore and will eliminate the need for kill-weight fluids after each zone is stimulated and unloaded. In sandstone reservoirs that require gravel packing or fracand-pack applications, the completion tool configuration for the mainbore and lateral completions will differ. The mainbore completion below the junction can normally deploy traditional sand-control equipment.

Performance of conventional steam-assisted gravity drainage (SAGD) with horizontal well pairs is impacted significantly in formations with high-permeability lean zones. These lean zones rapidly halt the vertical growth of the steam chamber and spread the chamber laterally, resulting in water-loss issues and a significant impairment of the system to overcome barriers (i.e., low-permeability horizontal layers). The operating-steam pressure is lowered to reduce the water loss to the lean zone, and this in turn accentuates the impact of any barriers, thus giving rise to high steam-oil ratios (SORs) and lower production rates. A vertical single-well injector/producer was proposed that consists of six vertical propped planes installed at varying azimuths from the bottom to the top of the pay. Steam would be injected at the top of the pay, and liquids would be extracted at the bottom. The well would be operated immediately in SAGD mode (i.e., the continuous injection of steam and the continuous extraction of liquids), resulting in peak production achieved within 30 to 45 days. The system would be very efficient because of the immediate drainage available from the propped vertical planes, and also as a result of the full gravity effect on the drainage height at startup and a favorable steam-pressure gradient. Reservoir simulations show that the single-well system’s performance with high-permeability lean zones within the pay would be virtually unimpaired, both in terms of production rate and SOR. Clearly, the system’s operating pressure must be lower to reduce water loss to the lean zone; but, because of the top-down growth of the steam chamber, the permeable lean zone’s impact would be minimized. The net present value (NPV10) of the single-well SAGD system in 35-m thick Athabasca bitumen pay with a 5-m permeable lean zone was estimated to be greater than 6×NPV10 of conventional SAGD. The single-well SAGD system would be much easier to pressure balance and operate than conventional SAGD, resulting in a more robust system, provided the multi-azimuth, propped vertical planes are constructed continuously throughout the pay height.