The Raageshwari Deep Gas (RDG) field, situated within Barmer Basin in the State of Rajasthan, India, was discovered in 2003. The field is a tight gas condensate reservoir, with excellent gas quality of approximately 80% methane, low CO2 and no H2S. Since the permeability (0.01 - 1 md) is low in this reservoir, hydraulic fracturing is required to get substantial recovery from the wells. The field has been under production since 2010. The development of this field has been carried out in three phases and more than 150 fracturing treatments have been pumped in this reservoir till date to achieve sustained economical production. This paper deals with the lessons learnt and changes implemented in choke design through various development phases of the field. In the initial phase of field development, chokes with a low Flow Coefficient (Cv) were installed to meet the requirement of controlling the wells at low flow rates and high differential pressure. Later as the surface handling capacity increased, the chokes had to be de-bottlenecked, requiring additional Capex for new chokes. To avoid a similar scenario in the future, a comprehensive approach has been followed to envisage Cv requirement, considering well wise production profiles and surface handling capacities throughout the life of field. Since a single trim can't operate over the complete life-cycle of a well, trim interchangeability has been included in the choke design such that low and high Cv trims are interchangeable. Pre-mature failures of trims were observed in initial phase and a root cause analysis was done to ascertain the reason. Based on the analysis, trim metallurgy has been changed from Tungsten Carbide to ASTM A276 Specific Stainless Steel Grade 440C. Trims with newly selected mettalurgy have been installed in the existing chokes. The introduction of trim interchangeability has saved MMUSD 0.3 in the future Opex as the requirement of procuring altogether new chokes for late life period of wells is avoided. Initially failures in the trim bodies were observed as early as two months of commissioning but with the change in metallurgy zero failures have been observed with operational life of chokes being higher than four years. This has avoided significant downtime on wells and expenditure on regular trim changeovers. Although Tungsten Carbide is one of the most common materials used for constructing trims world over, there could be specific cases where-in other metallurgy may add better value. The workflow followed in this paper will help select a suitable metallurgy and can impart a significant value to the industry.

Vedanta Ltd, Cairn Oil & Gas operates a tight gas field which produces majorly from the volcanic reservoir. Commercial production is possible post hydraulic fracturing which has been established through successful fracturing campaigns in the past. Hydraulic fracturing in volcanics is a complex operation due to the inherent heterogeneity and associated uncertainty of reservoir properties in these tight formations (~0.1 md). With added challenge of stimulating infill wells landed in partially depleted zones, fracturing becomes the key operation governing the ability to meet production target, project timelines and associated costs. Based on new seismic data obtained during field production and previous campaigns, Cairn executed a development campaign and is now following up with an infill campaign to improve and sustain the production plateau in the Raageshwari Gas reservoir. With consideration of economics of the field development, a strong focus on continuous improvement, optimization and developing the subsurface understanding along with lean and integrated project and contract management strategies to improve operational performance were key to achieving project objectives. A continuous improvement strategy through production technology initiatives was applied to stimulation campaign by re-designing completion, exhaustive data gathering/analysis and optimizing stage count, proppant volume through machine aided data analytics, testing and clean-up time, minimize hookup time to achieve execution targets and accelerate and maximize production time. Proppant onset calculations and well operating envelop were re-defined to ensure longevity to wells. Apart from summarizing the key learnings of the re-development campaign from a petroleum & completion engineering standpoint, the paper would emphasize on the challenges expected & observed and mitigation methods in the infill campaign - the most noticeable of the challenges being depletion. The project resulted in successfully completing 42 wells with ~ 250 frac stages and strategically placing ~ 63 million lb of proppants in gas producing zones. This lead to the production increment of ~ 40% to the overall production which has proven critical to plateau extension. The learnings also form the basis of the future infill campaign. Apart from the technical considerations, the paper would expand on the integrated project management strategies which resulted into achieving volume targets within the assigned budget while managing the local considerations and field specific challenges during the execution phase. This paper lays out a framework on optimized data collection, evaluation and integration for continuous improvement. It maps the uncertainties associated with highly laminated reservoirs and challenges to look at in an infill campaign. Most importantly the Integrated Contract & Project Management framework would provide operators with valuable insights to execute a frac intensive development/infill campaign within the planned budget/resources.