Over the last 12 years, technology in the drilling and completions space has reduced cycle time and dramatically lowered costs for operators. With the adoption of re-stimulations, additional production is being gained from existing wells at a cost that is less than the cost of drilling new wells. However, there has been limited development of low-cost intervention techniques to restore lost production or to extend the life of existing wells.
To address this relatively untapped area of intervention, new tools and techniques are needed to revitalize older wells in unconventional reservoirs that are more cost effective than traditional intervention techniques.
The economics of a workover are challenged by the uncertainties of successfully removing the existing production tubing and replacing it with a newly designed completion. In response a tool and cleanout technique has been developed that improves the ability of 1.25 in. coiled tubing to clean out the 5.5 in. casing through the 2.375 in. tubing string, thereby eliminating the need to pull and replace the upper completion.
A recent application of this new technique in an unconventional well demonstrated that a modified jetting tool (Reverse Nozzle Bit Sub or RNBS), along with a regimented cleanout schedule, can clean out most of the lateral length and restore lost production at a greatly reduced time and cost compared to jointed pipe workovers. Additionally, using coiled tubing to spot acid along the length of the lateral in a uniform matter can remove scale buildup and clean up perforations for improved performance.
This paper will review the design, testing and field application of the new tool and technique as well as show early results.