Horizontal Geo-Navigation of Geothermal Wells
(Abstract to a Poster Session at the AAPG Convention)

Dennis D. Jenkins and Paul Sandwell
Geology, Energy Frontiers Services, Arlington, TX

For years operators have been using various software applications to assist in the interpretation of survey data and logging attributes in horizontal wells to collectively create the science and art known as “geo-steering.” The most common practices involve using Measurement While Drilling (MWD) gamma-ray data and other attributes to assist in the drilling of horizontal wells. The data helps by telling operators if they are drilling within a target zone, or if the bit is somewhere above or below the target. Within oil and gas plays, on average, the more important uses fall into one of these basic categories:

  1. The conventional geo-steering uses, such as staying in zone in an optimal manner.
  2. Detecting the location of faults, and other vertical discontinuities.
  3. Avoiding certain zones, and risk management of borehole placement.
  4. Hydraulic fracture stimulation design and planning.

Conventional geo-steering has been used for many years to allow operators to adjust the trajectory of the planned well path in response to geologic conditions, correcting the bit up or down and left and right as needed. To that, add the abilities to map which formations a well bore intersects, and to integrate data from several sources to create a stratigraphic model with very accurate fault throws, and you have geo-navigation. The lessons learned on what to avoid in oil and gas wells tell us what to look for in the production of hot water from geothermal wells. By turning this technology on its head, we can dramatically improve our estimate of the potential of a horizontal well-bore for geothermal use.

AAPG Search and Discovery Article #90078 ©2008 AAPG Annual Convention, San Antonio, Texas