Improving Well Production of CBM Wells: Increasing of Fracture Conductivity By Restimulating Fractures, Use of LWC Proppant & Tso Design
Agarwal, Apoorv; Sharma, Akash; Jain, Tarang; Kapoor, Harsh
Department of Petroleum Engineering and Earth Sciences, University of Petroleum and Energy Studies, Dehradun, India.
Coal bed Methane reservoirs are dual porosity reservoirs where most of the gas is stored in low permeability coal matrix by sorption. The paper suggests various techniques to optimize production of gas from Indian CBM fields where the low permeability reservoirs pose serious problem in recovery. It brings about a contrast between the CBM extraction techniques used in San-Juan basin and the various Coalbed Methane fields in India and also demonstrates the relationship between fracture conductivity, well productivity and economic viability.
In modest rate coal bed methane wells, it is generally accepted that very high fracture conductivity is needed to ensure dewatering, which has made 12/20 a common choice. The two successfully completed CBM wells in San-Juan basin were restimulated with 20/40 ceramic proppant which eventually lead to increase in production. The results from San-Juan basin wells bear ample testimony in support of this technique.
The field results are in analogy to the Damodar rift channel where the bituminous coal is found in abundance .Coal fields in India like Jharia, Bokaro, North Karanpur and Raniganj lies in Damodar valley. In the wells closure stresses are modest and the strength of ceramic proppant is generally not required. However, the improved non-Darcy characteristics of uniform spherical ceramic proppant have numerous benefits .The use of spherical synthetic proppants with minimal beta factors even in extremely shallow CBM formations have resulted in expansion of gas volume and high velocity in propped fractures, leading to large non-Darcy effects and corresponding benefit to higher conductivity fractures.
The paper suggests various remedies to ensure optimization of gas recovery from low permeable CBM wells by using methods like Restimulating fractures, use of LWC proppants & TSO Design and various fracture geometries in horizontal CBM wells
AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012