Bhardwaj, Charu (Cairn Oil & Gas, Vedanta Limited) | Ranjan, Vishal (Cairn Oil & Gas, Vedanta Limited) | Jetley, Shailendra Kumar (Cairn Oil & Gas, Vedanta Limited) | Tiwari, Shobhit (Cairn Oil & Gas, Vedanta Limited) | Ghosh, Anirban (Cairn Oil & Gas, Vedanta Limited) | Sharma, Swapnil (Cairn Oil & Gas, Vedanta Limited) | Bohra, Avinash (Cairn Oil & Gas, Vedanta Limited) | Kumar, Abhishek (Cairn Oil & Gas, Vedanta Limited) | Beohar, Abhudai (Cairn Oil & Gas, Vedanta Limited) | Sharma, Sidharth (Cairn Oil & Gas, Vedanta Limited)
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.
Panigrahi, Nishant (Cairn India Ltd) | Bohra, Avinash (Cairn India Ltd) | Ranjan, Ashish (Cairn India Ltd) | Nekkanti, Satish (Cairn India Ltd) | Kumar, Abhishek (Cairn India Ltd) | Kestwal, Ashish (Halliburton) | Vaibhav, Ankit (Halliburton) | Jain, Himanshu (Halliburton) | Kumar, Animesh (Halliburton)
This paper summarizes the completion designs and operational challenges of successful well completions in more than 400 wells in the Rajasthan onshore block of Northwest India. The Rajasthan onshore block has three core fields, with a total 37 oil and gas discoveries. These wells were completed in over three and a half years without compromising aspects of health, safety, or the environment. During the campaign, a commendable feat of zero HSE incidents was observed.
These wells are broadly categorized as development and exploration wells and include a variety of both open- and cased-hole well completions. The completion systems are wide-ranging, varying from monobore conventional completions to open-hole, sand-control applications. The scope of work and challenging parameters include highly deviated open-hole and cased-hole sections, along with complex workovers. A wide range of products and services were designed to maximize well production. The completion design included a variety of packers, flow-control devices, intervention solutions, and other relevant completion tools.
There were various operational, health, safety, environmental, logistical, and manufacturing-related challenges that were overcome to drill and complete the wells. The purpose of this paper is to provide insight into the well types, completion designs, and to discuss the associated challenges.
The technology and practices established from these successful operations have become the standard operating procedures for completion jobs. This paper will take the reader through the evolution of well-completions technology, from the early days, when perceived risk was both hindered and was the spark for innovation, to the present time, when this technology is routinely used to meet production and reservoir development goals.