Coiled Tubing Assisted Hydraulic Fracturing of CBM Wells in India Using CT-Deployed Hydrajet Perforation Technology
Sharma, Ajay¹; Bhalla, Dushyant²; Bhat, Sumit²
¹Coiled Tubing, Halliburton, Mumbai, India.
²Production Enhancement, Halliburton, Mumbai, India.
By the beginning of the third quarter of 2010, multiple Coal Bed Methane (CBM) wells had been fracture stimulated using pinpoint technology in West Bengal, India. The featuring well parameters which led to the high success rate of the technology were the shallow depth of the wells and multiple zone treatments per well. The technology was introduced to the well operators when their requirement was to increase the number of treatments completed per day as against conventional hydraulic fracturing.
Pinpoint technology pioneers a specific technique wherein target zones are selectively perforated by pumping abrasive fluids through a specifically designed coiled tubing (CT) deployed bottom hole assembly (BHA) in order to perform abrasive jetted perforating. This provides an economical and efficient method of perforating which is immediately followed by fracture stimulating the interval without removing the CT. This is done by pumping the fracturing fluid down the casing-coiled tubing annulus.
This treatment technique provides an easy and economical method of achieving depth correlation. The small seam thickness of the CBM zones to be fractured makes it imperative to have a precise depth co-relation technique in order to help ensure that the perforations are placed within the target seam. A mechanical casing collar locator is employed in this process which helps correlate the coiled tubing depth to the wireline depth. The discussions provided are focused on engineering best practices developed, optimization of resource utilization, increment in the number of treated zones per day and reduction of non-productive time.
A prominent feature of this treatment method is the hydrajetting technique which uses abrasive sand jetting to cut perforations through the casing, cement sheath, and further into the formation. It provides a cleaner and economical way of perforating over conventional perforating techniques, resulting in reduction of entry friction and larger perforation diameters, leading to enhanced communication to the reservoir and lowering of fracture initiation pressure.
This Pinpoint stimulation method involves the synergetic integration of CT and fracture stimulation disciplines of well services. This paper also will discuss the optimization of this tool which resulted in an increase in the tool life, reduction of downtime caused due to unnecessary round-trips of CT, consequently reducing total fatigue on the CT string.
AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012