Saudi Arabia's Manifa Offshore Field Development: The Role of Technology
Authors: Carpenter Chris 
Published: February 2015

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 25119, ’Saudi Arabia's Manifa Giant Offshore Field Development: The Role of Technology,’ by James Arukhe, Shadi Hanbzazah, Abdulrahman Ahmari, Saleh Al Ghamdi, and Karam Yateem, Saudi Aramco, and Moustapha Bal, Danish Ahmed, and Fernando Baez, Schlumberger, prepared for the 2014 Offshore Technology Conference, Houston, 5-8 May. The paper has not been peer reviewed.

A major challenge of Arabian heavy-oil development is the problem of generating competitive advantages through deploying technological innovations while making cost-effective solutions a crucial part of a firm’s strategy for rigless interventions. The purpose of this paper is to examine coiled-tubing (CT) -stimulation and -logging technologies used in the timely project execution of one of Saudi Arabia’s largest field developments to enhance matrix-stimulation success in a cost-effective  manner.

Introduction

The Manifa field is located in Saudi Arabia and measures approximately 45 km in length and 18 km in width, encompassing both onshore and offshore areas with water depths between 4 and 6 m. It was discovered in 1957, with first sustained production in 1964. However, because of low demand, the field was shut down in 1984. In 2006, a field-redevelopment plan was initiated with major capital spending. Drilling and development started in 2010.

New technologies have been enablers for the unique development of the Manifa field. To cover operations in the field adequately, 27 man-made islands were developed and connected by causeway. Manifa contains the largest number of extended-reach wells (ERWs) in the world; two-thirds of the wells in the field are ERWs by industry standards, some with a total depth (TD) of 37,000 ft, departing beyond 26,000 ft from surface locations.

The Manifa reservoir has five main layers. Two of these reservoirs targeted for development contain both heavy oil and relatively lighter crude. Generally, Manifa crude is heavy and sour (29?°API, 14% hydrogen sulfide in gas and 3% in oil). Production opportunities exist in the presence of formation heterogeneity and a relatively less-mobile-to- immobile heavy-oil layer between the aquifer and the zones above it. The reservoir has relatively low permeability. The viscosity of the heavy-crude layer affects the ability of the natural waterdrive to energize the flow of oil from below. Therefore, peripheral power water injection above the viscous layer was planned for the field to provide pressure maintenance and efficient sweep of hydrocarbons to the producers. Both injectors and producers are drilled with an overbalanced water-based-mud (WBM) system and are completed barefoot. In this field, the porosity is generally high, but the driving factors for a successful injector or producer placement include permeability and formation-fluid mobility, both of which vary significantly across the reservoirs. With heavy oil in place, the challenge was to place the horizontal-injector-well paths in mobile-fluid layers as close as possible above the nonproducible-heavy-oil interface, to ensure meeting injection-rate targets and to provide an optimal sweep of the lighter crude and minimize bypassed oil.