To advance the fundamental understanding of combined percussion and rotary drilling leading to the development of more efficient and lower cost drilling and exploration of hard-rock reservoirs.

Terralog Technologies USA, Inc. 
TerraTek (full-scale laboratory testing facility)

Location:
Arcadia, California 91006
Salt Lake City, Utah 84104

Percussion drilling with and without rotation has been shown to improve the rate of penetration in some hard formations. Other benefits of percussion drilling include the ability to use lower weight on bit, a longer bit life since the bit is not in constant contact with the rock, better hole deviation control and larger cuttings providing improved geologic interpretation. These potential and theoretical improvements have been difficult to achieve in field application. This project will conduct analytical characterization of percussion drilling mechanics and rock mechanics which will entail using state-of-the-art analytical techniques to analyze load and energy transfer during drilling operations, dynamic damage and fracture mechanisms in rocks due to compression and shear stress waves, cuttings displacement and transport mechanisms, and fluid flow around reciprocating and rotating bit assembly. This initial analytical effort will be followed by the development of a 3-D numerical drilling process model. The model will simulate particle mechanics, fluid flow, and cuttings transport. Laboratory testing under simulated downhole conditions will be conducted to validate the model. The drilling tests will measure borehole pressure, rotation, axial load, and weight on bit as well as the rate of penetration for varying rotation speeds, and hammer frequency and amplitude.

Work from this project will provide the industry advancement in the understanding of percussion type drilling. This advancement will be based on a computer model and associated algorithms that can better simulate the drilling process, whether it is percussion, rotary or a combination of both. This modeling encompasses the drill bit - rock interactions as well as the removal of the rock fragments and their subsequent transport by the drilling fluids. With a successful completion of this project, this model can be used by the industry in future research in bit and drilling fluid design. It is widely acknowledged that percussion type drilling can drill faster with less deviation of hole than other bits. Figuring out how to make this type of drilling possible and economic is the challenge that this project will help make possible.

Results:
The rock mechanics analysis and dynamic percussion tool models have been combined with the separate cuttings transport model to make a single model. Data from single cutter impact tests previously conducted by TerraTek were provided to Terralog to help in the initial calibration the model. Further lab testing was conducted at TerraTek. Single cutter impact tests and drilling test with a hammer bit are scheduled. The single cutter impact tests were run in groups of three to gather data on repeated impact at the same point. TerraTek was able to modify their equipment for these tests to modulate the pore pressure in the Berea Sandstone samples. Mancos shale was also used for these tests. These same samples wer used in the mud-hammer drilling tests. Smith International, who participated in an earlier DOE fund project to evaluate Mud Hammer drilling performance (NT40918), agreed to provide the use of their mud-hammer bit. These tests were used to further verify and calibrate the model.

This project is finished and the final report and software have been accepted.

$520,525 

$130,131

NETL – Tim Grant (412-386-5457 or tim.grant@netl.doe.gov) 
Terralog Technologies – Mike Bruno (626-305-8460 or msbruno@terralog.com)

Technology Assessment [PDF-458KB]

Images: 
Geometric layout, dimensions and initial vertical stress distribution of the 3-D drilling simulation. 
Modeling of cuttings transport. The three colors of the cuttings correspond to their origin beneath the bit.
Conceptual Model

Pertinent Publications:
Han, G., Bruno, M., and Khany, L., Percussion Drilling in Oil Industry: Review and Rock Failure Modeling, American Association of Drilling Engineers, AADE-05-NTCE-59. (paper prepared for AADE National Technical Conference and Exhibition, Houston, Texas, April 5-7, 2005)

Han, G., Bruno, M., and Dusseault, M.B., 2005, Dynamic Modeling Rock Failure with Percussive Drilling, ARMA/USRMS 05-819. (paper prepared for the 40th U.S. Symposium on Rock Mechanics (USRM) in Anchorage, Alaska, June 25-29, 2005)

Bruno, M., Han, G. and Honeger, C., Advanced Simulation Technology for Combined Percussion and Rotary Drilling and Cuttings Transport, GasTIPS, Winter 2005, p. 5-8.