Light-Workover Cementing Technique Extends Life of Mature Indonesian Field
Authors: Wilson Adam 
Published: February 2015

This article, written by Editorial Manager Adam Wilson, contains highlights of paper SPE 142827, ’Extending the Life of Mature Field by Light-Workover Cementing Technique,’ by Farid Hadiaman, SPE, Total, and Nilo Bianchi Neto, Schlumberger, prepared for the 2011 SPE Asia Pacific Oil and Gas Conference and Exhibition, Jakarta, 20-22 September. The paper has not been peer reviewed.

Light-workover operations (LWOs) are well interventions performed without pulling out or replacing the completion of the well. Extensive LWOs are required to maintain satisfactory production at the mature Handil field in Indonesia. Among the LWOs executed in the field, a wide squeeze-cementing campaign was applied. These LWOs are used to isolate water-producing zones and target prospective new reservoir sections. For the Handil field, a field study analysis led to improved workover intervention with an alternative cement placement technique.

Introduction

Handil field is a giant mature oil field at the Mahakam delta, Indonesia (Fig. 1). It has been producing since 1975, with current recovery factors of 49% for oil and 57% for gas. Cumulatively, the total oil produced is approximately 855 million STB and total gas produced is approximately 1.68 Tcf. Currently, oil is being produced at 20,000  BOPD, gas at 75 MMscf/D, and water at 130,000 BWPD.

Field Study Analysis

Handil is composed of small stacked reservoirs with peculiar properties along its multizone completion. In order to allow selective production from different zones, 75% of the wells have dual-string completion (Fig. 2). Some wells had been water-flooded, and others have different types of casing damage. Thus, most of the challenges are related not only to the reservoir itself but also to dealing with parted tubing and with completion and packer leaking.

Squeeze-cementing jobs are unique and challenging. Each job has to be specially analyzed and requires fit-for-purpose treatments. These jobs rely on multidisciplinary technology, requiring knowledge and skills in geomechanics, fluid mechanics, and, of course, cement/slurry systems. After decades of field and laboratory studies, when compared with primary cementing, squeeze cementing defies standardization as a general practice.

Technical Aspects. Similar treatments used to be applied for different well conditions. No tailored cement systems or slurry properties were proposed on the basis of completion conditions, placement methodology, and injectivity results. The following are some improvement points that were identified.

One Unique Job Design for Most of the Squeeze Treatments. A range of different design/execution possibilities was created on the basis of the injectivity test results. Different slurry recipes were prepared such that, if either low-, mid-, or high-injectivity results were encountered during the field test, the well would still be treated by a tailored slurry design.

High fluid loss with higher rheology is now designed for higher injectivity results. Lower fluid loss and thin slurries are used for lower injection rates.

Thickening Time Testing Schedule. A new thickening time schedule was implemented. For squeeze operation, the thickening time schedule should follow what is happening in the field as closely as possible.