Pilot to Full-Field Polymer Application in One of India’s Largest Onshore Fields

Fig. 1—EOR pilot diagram.

A normal five-spot polymer-flooding pilot has been conducted at the Mangala field, one of the largest onshore fields in India, and results are encouraging in terms of additional oil recovery and reduction of water cut. Polymer flooding has the potential to improve sweep efficiency in the field significantly and to increase expected ultimate recovery (EUR). The project is one of the largest in the world in terms of scale, polymer usage, and related facility and logistics.

Introduction

The main reservoir unit in Mangala field is the Fatehgarh group. Five reservoir units (FM1–FM5) have been named from the top down. Mangala contains waxy sweet crude oil with gravity ranging from 20 °API near the oil/water contact to 28 °API higher in the oil column. The crude has an in-situ oil viscosity of 9–22 cp, with live-oil wax-appearance temperature approximately 6°C lower than the average reservoir temperature of 65°C. The oil also has a high pour point of 40–45°C, which had a great influence on all aspects of the project and process design.

The development plan involved implementing a hot waterflood from production startup to maintain reservoir pressure and sweep reserves effectively.

On the basis of appraisal data, it was realized from the start that Mangala was a candidate for an enhanced-oil-recovery (EOR) process. Detailed laboratory evaluations and simulation studies suggested chemical flooding as the appropriate EOR process for the field.

A polymer-flood pilot was conceived on the basis of laboratory and simulation results. The pilot has been successful in terms of reducing water cut and increasing oil rate. Full-field implementation is now planned for Mangala.

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 169146, “Pilot to Full-Field Polymer Application in One of the Largest Onshore Fields in India,” by Dhruva Prasad, Amitabh Pandey, SPE, M. Suresh Kumar, and Nitish Koduru, SPE, Cairn India, prepared for the 2014 SPE Improved Oil Recovery Symposium, Tulsa, 12–16 April. The paper has not been peer reviewed.
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Pilot to Full-Field Polymer Application in One of India’s Largest Onshore Fields

01 June 2015

Volume: 67 | Issue: 6

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