Techbits: Multilateral-Well Strategies: Examining Benefits and Constraints
Authors: JPT staff _ 
Published: February 2015

To address multilateral-well strategy for new field-development and -redevelopment opportunities, an SPE Applied Technology Work-shop (ATW) on “Multilateral Wells” was held in Bangkok, Thailand, in July. Attended by 60 participants representing 30 different organizations from 15 countries, the session presented an opportunity to explore the specifics of multilateral requirements and applications with emphasis on geological and geophysical identification of multilateral applications, junction selection, multilateral-well drilling/window systems, multilateral-well completions, field case histories, multilateral well performance, and intelligent completions.
Tara Tiradnakorn, President of Unocal Thailand, set the stage for the technical agenda and discussion with the keynote address “Energy Demand Growth and Its Impact on Future Technological Development,” in which he reviewed the recent history and status of the energy industry in Thailand, technologies that have most effectively assisted area industry, and future development. Opening remarks also were offered by ATW Chairperson Ding Zhu, Assistant Professor, Harold Vance Dept. of Petroleum Engineering at Texas A&M U. The Program Committee included Bernt Aadnoy, Professor of Petroleum Engineering at the U. of Stavanger; Azlee Abu Bakar, Head of Well Engineering–Drilling for Petroliam Nasional (Petronas) Carigali Sdn. Bhd.; Ali Al-Saleh, Senior Drilling Engineer of Kuwait Oil Co.; Julie Bonner, Senior Drilling Engineer–Completion Engineering, Horizontals, and Multilaterals for Chevron Corp.; Neale Carter, Region Manager of Easywell Solutions; Henrik Dock, Drilling and Measurement Sales Manager of Schlumberger WTA (M) Sdn. Bhd.; Dave Knox, Completion Fluids Technical Manager of M-I Swaco; Drew Hembling, Completion Engineering Specialist of Saudi Aramco; Dan Hill, Professor, Harold Vance Dept. of Petroleum Engineering at Texas A&M U.; and Eric Upchurch, Consulting Drilling Engineer for Unocal Thailand.

Facts From Five Fields
Field-application experiences with the multilateral advanced-well concept spanned the use of reformable-metal technology in the North Sea, a maximum-reservoir-contact concept used in Saudi Arabia’s Shaybah field; fishbone wells in a heavy-oil field in Venezuela; window milling on a deep gas well in Saudi Arabia; and a trilateral intelligent completion in the Saudi Aramco Ghawar field.
In the North Sea, workshop participants learned how reformable-metal technology was used to achieve two 5-in.-internal-diameter wellbores at junction to accomplish a Technical Advancement of Multilaterals (TAML) Level 6 junction with 7-in. casing above the junction. With drilling and completion on two wells deemed successful, two additional wells are planned.
In the Shaybah field, lessons learned with the maximum-reservoir-contact concept included a best practice of a fork-type sidetrack, with flow controls installed in the main bore and long lateral length, regardless of lateral type (forked, fishbone, or both), resulting in the most benefit.
The Zuata field has 7-in. fishbone wells with slotted pipe down the main wellbore, and the fishbone wells are openhole completions. If a lateral collapses, there is no option for repair. The fishbone multilateral configuration delivered doubled production on average without doubling cost. When compared to the use of the fishbone configuration in other fields, this configuration performs best in a low-permeability, heavy-oil environment.