PETROLEUM DEVELOPMNT OMAN SULTANATE OF OMAN

Abstract

In 1990 PDO awarded the world's biggest Turnkey Drilling Contract with a scope of work for 112 wells for the development of the Lekhwair field. An option to drill an additional 56 wells was included.

This paper gives an overview of the strategy and objectives that led to the award of this Turnkey Contract.

The Lekhwair Turnkey Contract, which covers a large number of wells, was supported by the preparatory work of a Multi-Discipline task force. The team, consisted of staff from Drilling Engineering, Production Engineering as well as Petroleum Engineering. The main issues address by the task force were: to agree on the well designs in relation to the field development concept and to formulate the basic input for the scope of work for a Turnkey type Drilling Contract.

The paper discusses the Management principles for Turnkey Drilling Operations whereby the focus is given to Management of the Turnkey Contract, Quality of the Product, Health, Safety and Environment (HSE) issues and the Performance of the Turnkey Contractor.

Finally a summary of learning points, including innovations in the rig design as well a the novel approach to the management of subcontractors in this Turnkey concept are presented.

Introduction

This paper reviews the Turnkey Drilling Project in the A-North Area of the Lekhwair field located in the Northern part of the Sultanate of Oman.

In the Lekhwair field two oil-bearing carbonate reservoirs, the Lower Shuaiba and Kharaib formations, are the completion objectives for the development wells.

The two producing reservoirs require dual completions in the central part of the field and single producers more to the flank of the field.

The production from these reservoirs will be through gas-lift completions, supported by a water injection scheme.

To reach the pay zones, the wells penetrate surface formations where mud losses are frequently encountered. In the same interval the Umm Er Rahduma formation has aquifers with sour water flow potential to surface.

The Lekhwair Turnkey Contract was awarded in November 1990 to National Drilling and Services Company (NDSC). The scope of work for this contract, being a new approach for PDO, included fit for purpose well designs. These design innovations resulted from the recommendations made by a Multi-Discipline Drilling Optimization Team which was formed in 1989. The prime task for this team was to optimize the process of drilling the wells and to reduce the drilling-related expenditure for the Lekhwair A-North Field Development Plan.

Learning points from the Turnkey experience to date are included in this paper and discussed in detail in the last section.

OBJECTIVES FOR THE TURNKEY CONTRACT

After analyzing the results of water flooding of wells drilled in the pilot area, the Lekhwair field was further developed to increase production from 25,000 bbl/day to some 100,000 bbl/day in 1994.

The Multi-Discipline Drilling Optimization Team, in the first instance, established the basic input for a scope of work to drill a minimum of 112 wells with a option to drill a further 56 wells.

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