Application of Radial Jet Drilling Technique with Gyro System to Enhance Reservoir Potential in Mature Sand Stone Reservoir in Assam-Arakan Basin Candidate Selection to Execution: A Detailed Case Study
Authors: Saikia Partha Protim , Dutta Udai Anand , Tumung Ranjiti , Verma Sanjay , Ahmed Akhtar Uddin , Mukerjee Aditya 
Published: April 2019

Radial jet drilling is a widely used environment friendly technique to improve well productivity in tight reservoirs, accelerate production in low-to-medium permeability wells, revamp production in mature wells with formation damage. This technique has helped to enhance production from mature field by bypassing skin, extend the connectivity of the wellbore beyond the near well bore area by drilling laterals using high pressure water jet, and thereby alleviate production restrictions caused by near well bore damage and extend the reach of the wellbore far into the formation. Production, being dependent on reservoir contact of the well bore is therefore increased as average reservoir contact is enhanced by the drain holes. However, selection is equally important as all wells cannot be considered as a suitable candidate and unsuitable candidate selection can show detrimental outcomes.

The technology was applied in a sandstone reservoir where a 22 mm hole was created in the casing at the target depth and then 50 mm OD lateral of length 100m was drilled in the reservoir using high pressure hydraulic jet. The accurate placement and orientation of downhole tool plays a significant role in the success of this technology and is found to be always challenging. Preventing casing milling in undesired azimuths, eliminating chances of lateral overlapping are some challenges that essential to be addressed for gaining optimum advantages. One of the promising technologies to address these challenges was the application of Surface Recording Gyro System. The application of surface recording gyroscopic well bore navigation system provides accurate placement of tool for lateral exit in the down hole and thus enable creation of lateral in the desired direction.

This paper discusses candidate selection and execution carried out in 7 nos. of wells in OIL INDIA LIMITED utilizing surface read out gyro system, which was done for the first time in INDIA. This paper also discusses about a post job analysis and lesson learnt with depths varying from 2414m to 3472m, the deepest well in India where radial drilling was carried out successfully. Post radial drilling on wells which had no/poor production prior to radial drilling showed very encouraging results. It also details about criteria of well selection, step by step procedure of the process, bottom hole tool selection, jetting and milling fluid used along with function, application, advantages of surface read out gyro system.

As stimulations and well preparation in complicated wells are capital intensive, it was critical to identify the most-suitable candidates with the available dataset before attempting well preparation and further acquisition. This was addressed through a customized workflow to design and creation of the horizontal laterals in desired azimuth utilizing the surface readout gyro system along with radial jet drilling for maximizing oil recovery.