Abstract

Mehsana tectonic block in North Cambay Basin is a fairly well explored, productive block where oil is both heavy and light. The block is now in a mature stage of exploitation associated with EOR techniques. Since oil production commenced in 1968–69 with a meagre 26 tons/day, the main fields have been developed through well planned development schemes. The recovery factor is intimately associated with reservoir heterogeneities, manifestation of environments of deposition, drive mechanism, fluid properties, pool size and depth of occurrence. These inherent characteristics are further influenced by reservoir management practices. The decline in oil production of the nineties was arrested and consistent growth since 1999 has been effected through efficient reservoir management practices accentuated by commencement of induction of technology.

IOR strategies with the objective of enhancing

  • Recovery and

  • Production;

are in vogue in the asset and began with revisiting the field geological and reservoir models. Strategies include:

  • Infill drilling recovery mechanism;

  • Initiation/Modification of water injection;

  • Enhanced oil recovery through Insitu combustion technique in heavy oil fields

  • High technology drilling like horizontal, high-angle-high drift wells and ultra-short radius drain holes and

  • By passed reserves identification and recovery methods like microbial methods addressing recovery enhancement.

Production sustenance and enhancement through

  • Artificial Lift optimisation

  • Massive hydraulic fracturing

  • Well bore chemical stimulation in heavy oil fields and paraffin intervention in light oilfields

  • Flue gas utilization

  • Unique flue gas shut off in heavy oil belt

  • Improved sand control measures and

  • Improved sick well treatment are in place.

The results from these schemes in terms of incremental oil are encouraging and have helped increase oil production marking a paradigm shift from earlier practices. Plans are afoot to foster improved production growth rate to increase ultimate recovery in tune with the newly set standards and accelerate brownfield development.

Introduction

Mehsana tectonic block is a fairly well explored, productive block of North Cambay Basin in the western Indian state of Gujarat with more than four decades exploration history (Fig-1). Mehsana block is one of the five major tectonic blocks of intra-cratonic rift Cambay Basin. Exploration activity commenced in the early sixties and easily locatable prospects have been drilled and the discovered fields are in an advanced stage of exploitation. The block encompasses 6000 square kilometres of which nearly 700 square kilometres fall in established oil field area. Nine oil fields with recoverable reserves greater than 3 MMt have been proved.

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