Abstract

" Snubbing" and " Hydraulic Workover Unit (HWU)" are words not often heard in Shell operations, unless used for special projects. However, they do serve a good purpose when used correctly. In an environment where rigs are expensive and attract many " disturbances" by communities, they can be used as an effective alternative to well workovers.

The Hydraulic Workover Unit supplied by an indigenous contractor is in line with the drive to support local contractors in developing expertise in the areas of well completion, work over and abandonment. The current arrangement is for the indigenous contractors to work under the umbrella of a multinational company such that in time they can become autonomous.

These considerations were the main driving factors to initiate the " Otumara workover campaign," (to prepare wells for gas-lifting), with a HWU instead of a rig.

This has resulted in potential cost savings of about US6$ million, increased oil production potential by 30–40,000 bbl/day, increased indigenisation of the Nigerian Oil Service industry in Nigeria, and is a prime example of a paradigm shift on " how to do things differently."

Introduction

The Otumara workover campaign was lined up to be done with a SEWOP and HWU rather then with a drilling rig to prepare them for the gas-lift project. For the 12 well campaign, a minimal saving of US$ 6.2 million could be achieved on a total budget of US$ 21.3 million as against using a drilling rig. In turn, the drilling unit would be able to drill additional wells in line with the company's production aspiration of 1.4 million bopd by the year 2003. It was estimated that between 30,000 to 40,000 bopd could be achieved during the estimated 140 rig-days work program.

Background

The Drilling group did identify considerable cost savings by the utilisation of a separate Workover (WO) unit to do completions, work-over's and abandonment's. Overall predicted savings were US$11 million per year per swamp unit and the possibility existed to extend the workscope and savings over more operations (FYIP and EA) for a longer duration.

In June 2000 a discussion was held between the Head Well Engineering Operations Warri and a group of contractors, to see how we could do things smarter. Out of those discussion the idea was born to utilise a WO-unit to do completions, workover's, well testing and abandonment's. This lead to the start-up of the " Otumara campaign" for the Northern Swamp area team, with predicted savings of close to US$6 million over 168 days, and simultaneously freeing up the drilling unit planned for that campaign to do drilling.

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