Attachment 5- 2010 Updated Est of Project Life 0001

February 11, 2010

Mr. Andy Nicholas
U.S. Department of the Interior
Bureau of Reclamation
Post Office Box 49
Bedrock, Colorado 81411

Re:

2010 Updated Estimation of Project Life
Subsurface Project 60Z6449

Dear Andy:
Pursuant to your request, we have updated the injection data for Paradox Valley Injection Well No. 1 and revisited the predictions for the life of the well. Generally, the estimates of ultimate project life have not changed appreciably, but they have narrowed somewhat.
Subsurface submitted an Estimation of Project Life on December 19, 2005. For reference and convenience, that complete document is attached to, and made part of this report. Since the report was submitted, the BOR has modified the surface injection equipment to a maximum surface injection pressure rating of 5,300 psi. The increased maximum injection pressure will significantly extend the reservoir life. However, as the pressure increases in the reservoir system, there is also the increased likelihood that the frequency and magnitude of seismic events will increase. This is addressed in detail in the recently issued Technical Memorandum 86-68330-2009-22. Specifically, the frequency of events in 2009 increased after a period of relative quiet in the years from 2005 through 2008. More correlation is discussed later in this report. Since the 2005 update, injection has continued according to the planned schedule of 160 injection days followed by 20 days of shut-in time to allow the reservoir to “relax”. The injection rate is nearly constant at approximately 230 gallons per minute, except for planned shut-down periods and occasional mechanical problems. Figure 1 is a graphical display of the injection rate and pressure history from 1996 through 2009. The gradually increasing magnitude of injection pressure is apparent in Figure 1. The uppermost trend is the calculated bottom hole injection pressure which is based on the measured surface pressure, brine density, and friction at 230 gallons per minute. The middle trend is the measured surface injection pressure. The scale for the upper and

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Andy Nicholas
U.S. Department of the Interior

February 11, 2010

middle trends is on the left axis. The lower trend (red) is the injection rate in gallons per minute, with the scale displayed on the right axis. A line has been inserted in the upper trend at the approximate value of the bottomhole pressure during the high-rate injection