Abstract

Radial Jet Drilling (RJD) is an unconventional drilling technique using the jet energy of high velocity fluids to drill laterals into the reservoir formation as an alternative to the traditional stimulation technique. In this subject case study, the productivity index in a Middle Eastern well had dramatically declined due to the excessive observed bottomhole pressures. In order to improve the production conditions, a workover operation was recommended using the state-of-the-art RJD technique. The paper explains the stepwise job procedure in the drilling well plan and operations. The production conditions were compared prior to and following the RJD. Finally, the reasons for the limited success of the operation and the lessons learned for guarantying future jobs success are provided.

For the RJD perforation in the well, two assembly runs were required: 1) running the RJD assembly consisting of 5/8-in drill bit, the mud motor and the coiled tubing pipe through the drill pipe, in order to open the window in the casing, and 2) running the jet nozzle assembly (no rotation) below the coiled tubing pipe in order to drill into the formation and extend the laterals to the projected lateral depth. Following the review of these procedures and operations, the paper makes a comparison between the plan and the real experience and provides the reasons for the discrepancies.

The number of 14 lateral holes (six holes of 131 ft(40 m) lateral depth and eight holes of 65 ft(20 m) lateral depth) with the aperture size of 0.25 inch, were planned to be drilled by RJD. In practice, the number of only eight laterals of different length ranging 34–65 ft(9–20 m), were drilled due to improper design and operational challenges. Comparing the production conditions following the workover with the previous production conditions, a productivity enhancement of 50% was observed with RJD drilling. However, the operation had several drawbacks: the number of the drilled laterals was less than planned, their penetrated length of the laterals was lower than the planned, and the duration of the well drilling was also greater than the planned rig time. Therefore, the operations was a limited success overall. This is attributed to the smaller coiled-tubing size selected, the performance of the jet nozzle used, and the inexperience of the personnel, among other factors.

The paper provides the dos and don'ts of RJD, as the first application of RJD in this field and the lessons learned from the field practice, future wells can be drilled with great enough number of laterals, their penetration length and lower cost. Therefore, the planned well productivity would be further enhanced, thereby, full success from the application of the RJD technique can be achieved.

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