Characterizing the flow units in Carbonates with Production logging and Borehole Images: Developing a workflow in Western Offshore India
Authors: Shrivastva Chandramani , Avtar Ram , Singh K.J. , Majithia Pritpal Singh , Pandey Arun , Sikdar Koushik , Kumar Ajit 
Published: March 2015

The first ever compartmentalized flow profiling job in a horizontal developmental well in India was a success as a result of seamless completion design, pre-job, on-job and post-job planning and job coordination. The completion strategy of the well was the core contributor for the success of the well. The integration of borehole images with conventional LWD petrophysical logs helped in identification of the key facies as different flow units, due to their different textural and petrophysical behavior. Based on the petrophysical and geological characteristics, placement of swell packers, slotted liners and blinds were designed to complete the well. The secondary porosity and connectedness co-efficient derived from the borehole images provided major control on segmenting the borehole.

The different facies identified in the pre-job planning corresponded nicely to the flow units identified on production logs. It helped in identifying the zones that contribute to the water cut most and need to be avoided while completing the well. Carbonate formations from this Western Offshore India field pose various development challenges due to the inherent uncertainties with their petrophysical and geological characterization. In order to optimize the production from the development wells, a proper integration of existing technologies is imperative. High end production logging techniques for horizontal wells were made use of to determine water and gas breakout (if any) and to determine the relative contribution of each compartment. The conventional production logging sensors like spinner, temperature and pressure were combined with the advance holdup sensors and beyond the pipe vision of nuclear tool to produce a consolidated and accurate image of the flow profile.

A diagnosis was made based upon the results derived from integrated analysis and a remedial plan was suggested which helped to increase production. This paper describes the entire workflow involved in planning the completion to create compartment and carrying out a flow profiling job in a horizontal well using advance production logging methods with borehole imaging. Being the first of its kind in India, this study provides a methodology for the optimum exploitation of the horizontal wells in development fields.

Introduction

The Western Offshore of India (Figure 1) has been a prolific hydrocarbon producer for a long time now. Many oilfields have been discovered and developed in the last thirty years in this part of India. The western offshore India has proven reserves in carbonates, clastics and the basement. The most prolific field of the area, Mumbai High is producing mainly from Miocene limestones. The Eocene limestones (Figure 1) are also very good reservoirs and are being developed in some of the smaller field. The study area (Figure 2) lies in Western Offshore of India where the Eocene limestones were evaluated using the borehole images for facies differentiation and subsequent application in identification of flow units.