Abstract

Qatargas 3 and Qatargas 4 ventures are jointly developing their assigned project area of the North Field offshore Qatar, the world's largest non-associated natural gas field.

The area allocated to the joint development is a 15km by 20.5 km block and consists of 3 15-slot platforms, each with 11 wells drilled into the Khuff carbonate reservoir.

Currently the Qatargas 3&4 block is in its late development phase where over 75% of its wells have been drilled, evaluated and completed. The formation evaluation is generally carried out using data acquired by wireline conveyed tools and a standard log acquisition program consist of two runs configured to record mainly resistivity, porosity, sonic and formation pressure data.

This extensive data acquisition program entails substantial operational challenges. Because of this, a clear understanding and management of human related factors such as communication, logistics and experience of personnel as well as technical challenges such as hole conditions (clean up), well trajectory, tool configuration, deployment methods and overbalance and risk management are critical to success.

Introduction

In December 2005, Qatargas3 (QG3) venture (68.5% QP, 30% ConocoPhillips and 1.5% Mitsui) finalized agreements with Qatargas4 (QG4) venture (70% QP and 30% Shell) to jointly develop the Project Area of the North Field assigned by Qatar Petroleum (QP). The agreements included joint subsurface development and construction of offshore and onshore facilities in order to capture the synergies for a 2-train LNG development. The two separate projects have a combined Joint Asset Development Team (JADT) - QG3&4 - which is staffed by secondees from Qatargas, ConocoPhillips and Shell, as well as third-party direct hires. Upon completion of the offshore development and onshore construction, the QG3&4 project will be operated by Qatargas Operating Company Limited, (OPCO), a company established with the specific purpose to execute, operate, maintain, and service all Qatargas projects.

This paper provides an overview of these challenges and the involved processes that drive continuous improvement. Improvement was achieved on multiple aspects of the logging program, such as efficiency increase and time optimization of over 65%, and data quality improvements. Practices commonly adhered to include pre-job planning or Log the Well On Paper exercises (LWOP), thorough follow up during execution, mandatory close out by all parties involved in regular service quality meetings, job debriefing with engineers and continuous review of standard operating procedures and best practices. Significant efforts were placed on logging tool conveyance and configuration selection which ultimately led to a decision tree being developed to accommodate the various options.

The processes developed by QG3&4 over the last three years could offer a ‘running start’ for new operators who target similar formations in the region.

Block and Data Acquisition Overview

The area allocated to the joint development is a 15km by 20.5 km block totaling 308 sq. kms. The Plan of development consists of 3, 15-slot platforms, each with 11 wells drilled into the 1500ft thick layered carbonate reservoir of the Khuff formation.

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