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When wellbores are deviated or are located in tectonically active areas it is unlikely that the plane of the wellbore and an artificial hydraulic fracture will be co-incident. This could result in limited entry effects due to poor communication between the wellbore and the hydraulic fracture or the presence of multiple fractures, and hence in a reduced well productivity. A combined experimental and theoretical study has been carried out to investigate the influence of key parameters on the fracture-wellbore communication, aiming to identify the potential problem wells and to aid in optimising completion procedures for a North-Sea gas field. The hydraulic fracture treatments were successfully placed, though the fluid friction experienced over the perforations during the treatments did show a dependence on well orientation (indicative that a minor form of limited entry was occurring).

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Some new and further developments of offshore fields in Abu Dhabi expect to exploit extended reach drilling (ERD) whereby large numbers of wells are drilled from drilling centers on artificial islands or large platforms. The wells will also have increasingly long reservoir sections (up to 10000 ft), so-called maximum reservoir contact or MRC wells. Artificial islands may have a much larger well capacity (200 or more wells) and larger slot separations (15-30 ft) than platforms but optimal well allocation and sequencing is far more complex than for single cluster platforms. Large numbers of wells (producers and injectors) require multiple clusters separated by 100-200 ft in order to accommodate rig layouts, allow rig movements and access to all slots. Cluster and slot layouts also impact and are impacted by facilities layouts of manifolds and flow lines.