Abstract

This paper outlines a short introduction of the status of the implementation of Expandable Tubular Technology in PDO in general and the job history of a short Expandable Sand Screen (ESS) installation in cased hole. It highlights the benefits of using ESS for such applications in terms of cost and production. This ESS installation also involved the first use of a modified section of a casing patch as a hanging mechanism.

Expandable Tubular Technology in PDO.

Expandable Tubular Technology (ETT) is strategic to PDO because of its potential to add value and lower cost. ETT can be divided in solid and slotted expandable tubulars.

In PDO the following applications have been identified for solid expandable tubulars: Open hole clads to shut-off water, unstable formations and to solve lost circulation problems. Cased hole clads to repair corroded casing intervals or to shut off a perforations. Expandable liner systems to maintain hole size. Expandable liner hangers will increase the reliability compared to conventional systems by the absence of moving parts.

Applications of slotted expandables are the cemented expandable slotted liner and the Expandable Sand Screen (ESS) as a means of down hole sand control. Two successful installations of the cemented expandable slotted liner have been performed in PDO this year (Reference 1).

Expandable Sand Screen (ESS) in PDO

Introduction

Sand Control is one of the Challenges that is facing the oil production of the south part of Oman, some 25% of PDO's production requires some form of sand control. Many techniques are utilized to overcome this problem, including the use of conventional Wire Wrap Screens (WWS), Gravel pack, Pre-drilled liner and lately the ESS.

Expandable sand screens, when installed in open hole, have the advantage of full contact with the formation. This contact eliminates any sand grains being accelerated in to the annulus causing screen erosion or screen plugging. The Expandable Screens provide a larger ID which improves the production performance, facilitates future well interventions and effective zonal treatments.

Introduction of ESS in long horizontal sections is currently considered as costly, but if it is compared with the negative sides of other completions, it may become the excepted method. The WWS, as seen from a different fields in PDO, plug regularly with fines and more than twice a year a workover operation is required. This has a significant impact in the well productivity and also contributes in the lost of value of deferment oil production. Gravel packed wells may have a similar production performance as ESS, but installation requires more time, carries a greater risk and zonal isolation is not possible after installation.

A five well campaign of ESS in Marmul and Nimr fields has been committed and will be installed during the summer of 2001. The 4" ESS will be placed in 400 m and 550 m horizontal sections in Nimr and Marmul respectively, and expanded to the 6–1/8" open hole size. The objectives of these installations are to establish the difference in initial production performance, the longer term productivity profile and the influence of the ESS on (early) water break through and finally the ultimate recovery. At the same time, two similar wells in Marmul will be completed with a horizontal gravel pack to allow for a direct comparison with the ESS and conventionally (WWS) completed wells in this field.

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