Two different horizontal water jet drilling systems have been developed and extensively field tested. The first, the Ultrashort Radius Radial System (URRS) is built around 32 mm (1- ¼ inch) coiled tubing and provides multiple 30 to 60 m (100 to 200 foot) radials from a vertical borehole. Accuracy is ± 2 to 3 ° in vertical trajectory.

The second system, the Remotely Piloted System, uses 114 mm (4- ½ inch) conventional flush joint tubing and is designed to drill for many kilometers (miles) with high three dimensional accuracy. Both systems incorporate Control While Drilling of the radial and provide real-time acquisition and display of drill performance with derived formation properties

References and illustrations at end of paper.


About ten years ago, Petrolphysics and its partner Bechtel began the development of the Ultrashort Radius Radial System. That water jet drilling system is described in several previous publications, among them References 1–8. Two water jet drilling systems have been developed for different applications and trajectories.

The first system, the Ultrashort Radius Radial System (URRS), is an extended completion or recompletion system built around 32 mm (1- ¼ inch) coiled tubing and designed to provide 30 to 60 m (100 to 200 foot) radials on one or several levels within a single vertical well. Integrated with the water jet drilling technologies in the URRS are real-time data acquisition, data analysis and interpretation, and open/closed loop control while drilling systems. This platform provides a powerful information system interface through which a multitude of operational data is channeled to a single operator for real-time qualitative and quantitative analyses of the drilling process. Combined with a time-window display and database of past drilling information, the system facilitates immediate well management decisions and solutions to difficult problems as related to the drilling process. (Figures 1 and 2)

The second system, the Remotely Piloted System (RPS), is also designed to provide multiple radials but at trajectories of up to several miles in length. The RPS is built around 114 mm (4- ½ inch) screwed flush joint tubing and incorporates a removable inner 63.5 mm (2- ½ inch) Drilling and Control Module (DCM) which may be removed and replaced by coiled tubing or sucker rods without tripping the outer 114 mm (4- ½ inch) drill string.

Systems Definition
A. Ultrashort Radius Radial System (URRS)

The particular properties of the URRS include the following capabilities. Specific references to each technology are indicated.

  1. Make a vertical to horizontal turn on a one-foot radius.1,2,7

  2. Provide multiple radials from a single vertical well.1,2,7

  3. Water jet drilling of borehole from a diameter of many millimeters (a few inches) to more than one-third meter (afoot) in a wide variety of rocks at high backpressure and depth.3

  4. Provide a variety of horizontal completions including travel packing. Flexible Sand Barrier (flexible permeable casing), and electrolytic cutting and perforating.6,7

  5. Flexible three dimensional positional logging with initial directional placement accurate to ± 0.5 °.

  6. Data acquisition and analysis to provide both real-time indication of operating systems effectiveness and downhole data on the formation.

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