Traversing the tight unconventional shale reservoirs is an Engineering challenge. The paradigm shift from conventional to unconventional reservoir resource exploitation was endured upon with Well CS#A, the shale gas/oil Well in Cambay Basin. The domain expertise in conventional reservoirs was manoeuvred, redesigned and translated into successful Hydraulic fracturing execution in CS#A. Frac data was further analysed and assimilated to draw the characteristic frac behaviour of Indian Cambay Shale. Cambay shale is the main source rock, thermally well matured and falls within the oil window but have never been explored for production before. Triaxial Compressive Strength Test with Acoustic Velocities and various lab tests were performed to determine shale rock mechanics and a suite of petrophysical properties. CBL-VDL-GR-CCL logs ensured good cementation. Specialised 3D model Simulator was used with the best input parameters to conceive the best and specific design for Cambay shale. Initially, slick water was used for Step Rate Test (SRT). MF analysis carried out to ascertain key informations and subsequently, changes were incorporated in Main frac design simulation. The frac fluid was exclusively designed and optimised through tests in Laboratories to give best results and to check the compatibility with Cambay Shale & post job flow back recovery. Closure analysis was done by the most reliable G Function time BHP analysis and the same was verified with Square root time plot. The real time pressure graph trend showed net pressure increase during proppant packing suggesting better frac behaviour and fracturing prospects. Post Job, the real time Net-Pressure match facilitated simulation of real time data to know the actual frac dimesions created after job, the frac profile, validate the permeability and stress, check the conductivity gain etc. The extensive and exhaustive research, planning and execution of hydraulic fracturing job in CS#A proved the producibility and potentiality of Cambay Shale as the Well has produced Oil. The Geological data, the log data combined with the experience gained and data inferred by exploitation of this Cambay shale gas/oil Well "CS#A" through Hydraulic fracturing will be a boon for the E&P of Unconventional Shale in India.

From 2005 to 2020, the application of hydraulic fracturing technology in India has touched the length and breadth of the country in almost every basin and reservoir section. The variety of reservoirs and operating environment present in India governed this evolution over the past 15 years resulting in a different fit for purpose fracturing strategy for each basin varying from conventional single-stage fracturing (urban, desert & remote forested regions) to high volume multi-stage fracturing, deepwater frac-packs and offshore ultra-HPHT fracturing. The objective of this paper is to present the milestones along this evolution journey for hydraulic fracturing treatments in India from 2005 to 2020. This paper begins with a review of published industry literature from 2005 to 2020 categorized by reservoir type and the proven economical techno-operational fracturing strategy adopted during that period. The milestones are covered chronologically since the success or failure of technology application in one basin often influenced the adoption of novel hydraulic fracturing methods in other basins or by other operators during the initial years. The offshore evolution is branched between the west and the east coasts which have distinctly different journeys and challenges. The onshore evolution is split into 5 categories: Cambay onshoreBarmer Hills & Tight GasEast India CBM and shale gasAssam-Arakan BasinOnshore KG Basin Each of these regions is at different stages of evolution. The Barmer region is in the most advanced state of evolution with frac factories in place while the Assam-Arakan Basin is in a relatively nascent stage. Figure 1 presents estimated hydraulic stage count based on published literature underlining the exponential growth in hydraulic fracturing activity in India. This paper enlists the technical and operational challenges present in the onshore and offshore categories mentioned above along with the identified novel techno-operational strategies which have proven to be successful for various operators in India. A comparison is presented of the different timelines of the exploration-appraisal-development journey for each region based on the economic viability of fracturing solutions available today in the Industry. Lastly, specific non-technical challenges related to available infrastructure, logistics and social governance are discussed for each region. This paper concludes by identifying the next step-change in the evolution of hydraulic fracturing operations in India among the 5 categories. Each of Government, operators and service providers have important roles to play in expanding the adoption of this technology in India. These roles are discussed for each identified category with the perspective of continuing the country's journey towards energy security.

This paper discusses the Hydraulic Fracturing (HF) treatment of the Andimadam Sandstone formation of Periyakudi field of India. The Andimadam sandstone is a hydrocarbon bearing formation, with estimated in-place reserves of 47.43 MMt (O+OEG) which was prognosticated after drilling and established hydrocarbon potential. Well PD#A was drilled in Andimadam Sandstone and HF in this well was attempted in order to develop and exploit the full potential of the oil and gas reserves of the field. The fracturing treatment of the tight gas reservoir in one of the deep well in Periyakudi field was performed eld. It was a challenge to carry out HF in well PD#A at such deeper depth formation. There was no previous information available to understand the formation and to predict its behaviour during HF treatment. HF treatment in tight gas Sandstone laid so many challenges. Formation breakdown, succeeding minimum rate required for fracturing and attaining high proppant concentration during job with crosslinking gel under extremely strenuous operational conditions and pressure limitations were some of the major challenges. Delayed cross-linked gel was used to minimize tubing friction pressure. Managing the pumping rate with pressure limitations during HF treatment was one of the major challenges. Execution of the treatment with low pumping rate results in stimulation of small volume of rock comparatively. All these limitations were overcomed by proper job designing, optimization of fracturing fluid and analysis of pre-frac treatments. A substantial amount of fracturing fluid and proppant placed into the formation maintaining all safety standards. Satisfactory flow back of frac fluid with gas was observed and high flow back pressure at surface was noted. This paper discusses challenges to execute hydraulic fracturing treatment in well PD#A and the lessons learned during the execution. In addition, it was the deep well (drilled upto 4945 m) in Periyakudi field with low permeability reservoir. Post analysis of pre-frac treatments done to obtain the reservoir properties and to design the main frac treatment. The results of fracturing treatment are also discussed. The promising hydrocarbon potential of the Andimadam sandstone which are based on post fracturing analysis, encourages further future development of the Periyakudi field, Cauvery Basin, India.