The following memo is from Phil Snider of Marathon Oil, and was distributed to all Stim licenses in September 2005.

HST Development Update

This memo is an update regarding the Propellant Technology Group’s efforts to assist in the development and optimization of the new Horizontal Stimulation Tool (HST) manufactured by Reliance Technology Specialists, and to encourage the use of this product by the licensees in appropriate applications. The HST is an addition to the existing product line including the StimGun™ assembly and StimTube™ tool, both manufactured by Owen/HTH and is not meant to replace either of these products.

Key points related to HST development are:

• The sealed detonating system of the HST has worked flawlessly, and has proven to be a very simple and reliable initiation method for the detonating train. This is a huge addition to the technology portfolio, providing the licensees a reliable, patent-pending system that works in an “exposed” environment. Long carrier systems in 2-7/8” and 2-1/32” diameters have been manufactured and utilized.
• While the HST propellant burns effectively at higher hydrostatic pressures in the test well, incomplete burns at lower pressures (500-700 psi) occurred in early testing. This issue has been resolved and is understood, thanks to an extensive series of tests conducted in a low-pressure (~460 psi) test well provided by Marathon’s Wyoming operations. Complete propellant burns with excellent pressure curves were achieved, and the Propellant Group now has an acceptable understanding of how to properly execute low-pressure HST applications. Additional testing at both higher and lower pressures will continue to further control and define the burn characteristics.
• Likely applications for the HST are long horizontal wells (where the improved economics are advantageous) and heavy oil wells. The HST will be a lower cost product for these applications due to the simplified manufacturing process. The HST system as been run through 45 degree per hundred build angles with no ill effects and complete retrieval.
• Letters are forthcoming to all licensees extending their StimGun™ Technology license to this patent-pending product at no additional license fee. A 12% royalty fee is included in the quoted sales price to the licensees. This approach to royalty collection is meant simplify accounting and to allow the suppliers to more readily quote volume discounts. Of course, it is up to the individual licensee to determine how, or if, to directly bill the royalty to the customer, but we always recommend that detailed and proper accounting practices be used. HTH and Owen Oil Tools can provide the HST product to the licensees if they desire and agreements between Marathon and these parties are being finalized to allow this.
  

1. The system was tested in Marathon’s East Texas 10,000 foot, 4,000 psi hydrostatic propellant test well, and burn data/pressure records compared favorably with similar runs using the StimTube™ Tool and the StimGun™ Assembly.
2. A subsequent test series was performed in the same well, with similar results, although the primary objective of this second test was to evaluate the explosive detonating train transfer.
3. Marathon utilized the HST system to stimulate a long open hole horizontal well with a 45 degree per hundred build rate and 500 psi BFP in the Tensleep formation at Oregon Basin, Wyoming. A 650 foot assembly with 28 2-7/8” carriers was used. The assembly included two sets of non propellant-loaded perforating guns to dampen the pressure wave across areas where no stimulation was required. Propellant burn varied from 90% to 55% and good pressure records were achieved. A report on this testing has been distributed. Although the burn efficiency was less than desired, the explosive transfer system functioned flawlessly.
4. A Canadian operator desired to stimulate a horizontal 3.5” cased hole in a coal bed methane well with ~750 psi BHP. A 2-1/32” x 50 meter HST assembly was run. Detonating cord type and wall thickness of the control line were altered in hopes of achieving a higher burn efficiency. Excellent pressure records were obtained, but unfortunately only about 10% of the propellant burned. Again, the explosive transfer system functioned flawlessly. Learning how to create a full propellant burn became the central effort of subsequent testing.
5. Marathon made two runs with the HST, both with and without control line, as well as with the StimTube Tool in a Powder River Basin coal bed methane well. In this case, the oxidizer content of the propellant was increased to help initiate burn. Good pressure records were obtained on all runs and were used to further evaluate design.
6. The Propellant Technology Group made 10 runs in a shallow Oregon Basin well in the Embar formation with 460 psi BHP. Variables examined included control line type, control line thickness, oxidizer content, and propellant geometry. Excellent pressure data were obtained, and complete propellant burns were obtained in the many of the runs. Just as importantly, incomplete propellant burns were obtained in some tests. This allowed the conditions necessary for complete burn to be achieved in lower pressure applications to be defined. Since detailed analysis is not yet complete, it is inappropriate now to share all of these data here. The Propellant Group (and in particular Bob Haney and John Schatz) will be willing to transfer this analysis individually to each licensee as appropriate.
   

As a result of this work, we now are confident that complete HST propellant burns with the desired characteristics to properly stimulate the formation can be obtained in virtually all environments, including those at lower pressures. This is very important for the lower-pressure applications, which appear at this time to be the predominant market for this HST system. There will always be conditions for which we will recommend against running the tool, but this should not restrict most applications.

If you have any specific potential applications, Bob Haney or Stan Wall are suggested as the initial contacts. Furthermore, John Schatz is confident that the PulsFrac™ Software will do a good job of modeling the HST product, although additional data are needed to provide a fully statistically-accurate definition. To this end, we encourage that all licensees when running the HST attempt to incorporate a high-speed pressure gauge. The HST will be added to PulsFrac as an additional drop-down menu choice with automatically-set parameters, as for other tools. For now, we recommend that you contact Bob Haney regarding the setting of burn parameters.

Available only to licensees of the Propellant Technology Development Group.

Download Product Spec Sheet (PDF)