Beyond Sand Control: Using Expandable Systems For Annular Isolation and Single Selective Production in Open-Hole Completions
Authors: Montagna James N. , Popp Tim , White William G. 
Published: October 2008

This paper discusses the planning and application of expandable systems to provide effective open-hole sand control with zonal isolation. It will present a case history of the world's first completion set inside an expandable system to provide a single selective well, where one could selectively produce, or commingle from different zones. Control of the formation sand was provided by expandable screen, open-hole zonal isolation by expandable packers with solid pipe and a conventional completion packer set inside expanded solid pipe for selectivity. The expandable system was run in a synthetic oil base drilling fluid that was used to inhibit swelling of exposed shale.

Introduction

The Attaka Field is located in the Makassar Strats, about 12 miles (19 km) offshore from Tanjung Santan, East Kalimantan, Indonesia, northeast of the Mahakam Delta. The areal closure of the structure is 8,000 acres (3,300 hectares).

In March 2001, this super-giant oil field surpassed 600 million barrels of cumulative oil production. It has produced since November, 1972 with a peak production rate of 110,000 BOPD in 1977. Most of the Attaka reservoirs have weak to strong water drive, although some produce strictly under solution gas drive or gas cap expansion. Oil gravity ranges between 35 and 43 degrees API.1

A majority of completions in the shallower intervals at Attaka require sand control. However, marginal reserves in many of the reservoirs necessitate low cost completion techniques, often involving more than one interval. Typical sand control techniques would be use of a gravel pack, frac pack, or utilizing a horizontal well with stand-alone screens.

Many open-hole completions performed in layered reservoirs with different reservoir properties call for some method of isolation in the liner/open-hole annulus during the production, or injection life of the well. External and internal shut-off options are important to maximize hydrocarbon production or improve injection profiles. Understanding the technical and economical drivers for these types of wells, then developing a "best match" solution requires a complete systems approach. The solution may include either nonexpanding, or expanding systems, or a combination thereof.

The primary drivers for this completion were costeffective open-hole sand control with zonal isolation and selective production; produce oil then gas.

Case History

Planning.

The reservoir's production history dictated sand control. Sieve analysis from gas and oil sand sidewall cores were available from adjacent wells. Previous fluid sensitivity studies indicated synthetic oil base drilling fluid for the high clay content section between sands. Fluid samples were available from active drilling on adjacent wells for screen flow tests.

With well design data (summarized in Table 1), sieve analysis and drilling fluid samples, risk assessment studies were performed. An expandable systems solution was recommended.

Sieve Analysis.

Mechanical, dry sieving was performed2 and data indicated uniform distribution3 of particle sizes (Cµ = d40/d90&lt; 3) for both the gas and oil sands. The gas sand d10 value was approximately 180 micron. The oil sand d10 value was approximately 400 micron. For contingency purposes, the expanding screen weave opening was sized to the gas sand d10 value for both zones. From a systems approach, application of smaller screen weave openings requires more focus on drilling fluids management; sized solids conditioning or displacement to solids free drilling fluid prior to running screen in the we