Abstract

This paper describes a large-scale field study that demonstrates the relative merits of four different approaches to a single problem. That single problem is the clogging of wire wrap screens in gravel packed producing oilwells resulting in poor well performance. The four methods evaluated are: -

  • Jetting with acid using coiled tubing

  • Bullheading foam diverted acid

  • Bullheading acid diverted with benzoic acid flakes

  • Squeezing acid between opposing cup packers

A total of 168 well treatments are evaluated within this paper. The large number of wells permits meaningful comparitive data; the statistical spread of the data has also been evaluated.

The data clearly shows that by far the most effective way of placing acid across a wire wrap screen is to jet with coiled tubing. This method provides for better well response, smaller acid volumes, faster jobs and a better than average cost per foot figure.

A payback analysis has also been conducted.

Introduction

The Duri Steam Flood (DSF) field is a multi-billion barrel heavyoil-producing field that lies on the central Sumatra basin, Indonesia as shown in figure 1. It is operated by Caltex Pacific Indonesia (CPI), a Chevron Texaco affiliate.

The field consists of 4,114 producers, 1,610 steam injectors and 405temperature observation wells. The current total production of the field is approximately 235,000 BOPD so making the average production per well about60BOPD. With a total coverage area of 35,000 acres, the field is divided into13 smaller areas, where area 1 to 9 have been fully developed and put under an extensive steam flooding program. Area 10 began development at the beginning ofyear 2000 and the other three areas are still under the planning phase.

Thermal enhanced-oil-recovery (EOR) methods are implemented to reduce oilviscosity and so improve oil recovery from this heavy oil bearing formation.Active steam flooding began in 1985 and typically involves one steam injectorwell surrounded by a pattern or producing wells. One temperature observation well is often set in the pattern to monitor the formation's temperature response to the steamflood.

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