An Integrated Approach for Sustainable Development of Mature Field Using IOR Techniques: A Case History of Oligocene Sand of Upper Assam Basin, India

Abstract

Sustainable development of a mature field depends on various factors, which can be categorized into well level and reservoir level. This paper is a summary of experience of various techniques used at well level and reservoir level. The objective is to sustain/increase the level of oil production and reduce watercut using various completion methods & pressure maintenance. This Paper will elucidate a Field Development Plan for a mature field. Several possible options were tested like 1. Possible workovers 2. Combination of Horizontal and Vertical wells based on firm and dependent locations 3. Infill short lateral wells 4. Optimal production rate to minimse pressure decline by limiting the gas production and hence putting a check on GOR 5. Water injection strategy 6. Intelligent Oil Field Completion using ICD (Inflow Control Device). For the purpose of testing the best possible course of action; the reservoir was modeled and history matching was done with satisfactory results. Prediction Strategy was then deployed at simulation stage. The financial analysis for all the prediction scenarios were also carried out using Net Present Value (NPV) method to check the feasibility as well as profitability of the various envisaged Production Strategies. Based on the analysis, the maximum recovery was obtained from a combination of infill wells and ICD completion, but on monetary grounds, the best case consists of workovers and horizontal wells to tap the oil from segregated pockets. In the end, a comprehensive and extensive comparison of all the possible way-through options are discussed with pros and cons of each one. A sensitivity analysis was performed on economic parameters (e.g. crude oil price, operating cost, Taxes, Royalty, capital expenditures) to analyze impact on various economic indicators. This Paper presents novel ideas into the ever expanding sphere of Field Development. It presents an extensive review of the various aspects of mature field development and their economic analysis. The field in discussion is Makum-North Hapjan which contributes around 40% of total production from OIL's fields in North-East India. It has been under production since 1993, with 62% of the production coming from horizontal wells.