Geothermal Drilling Project - David I. Norman, New Mexico Tech Earth & Environmental Science

GRED III Geothermal Drilling Project Progress
David I. Norman, Professor of Geochemistry

Dave Norman and former NMT professor Harold Tobin are exploring M Mountain for a geothermal energy source that can be used to heat buildings around campus. The drilling site is close to Woods Tunnel, pictured at left in a file photo by Susan Delap. You can just barely make out the M on the peak to the upper right. Weekly progress reports written by Dave will be posted here as they are received, the most recent ones at the end of the page.

We completed Phase I studies and submitted an exhaustive report to DOE-Geothermal Office in August, 2005. Sandia geologists who oversee the GRED program asked that we submit the report several months early, which we did. About half the projects were cancelled; project ranking was in part on when Phase I reports were submitted.

Permission to continue to Phase II drilling was received in November. We were aghast when we started to look for drillers. High oil, gas, and base metal prices and high steel costs caused drilling costs to triple. Few if any drill rigs were available. Most drilling companies did not bother to return calls.

We went out for bidding twice during the first six months of 2006. The first exercise resulted in one bid of $800,000; our budget was $250,000. In hopes of attracting a water well drilling company and less costs we reduced our drilling depth from 3000 ft to 2000 ft, changed the drilling method from coring to rotary drilling, and moved the drill site to a less desirable, but more accessible location. We received one bid for $400,000 with no promise that drilling would be completed in the fall.

About July 1 I found out that DOSECC had a rig available because a planned project was cancelled. Dennis Nielson, DOSECC Head, visited NM Tech on July 6 and gave us a preliminary bid of $400,000 to drill to 3,000 ft hole with continuous core at our preferred site. A request was made to DOE–Geothermal for a cost overrun of $150,000 that was granted. NM Tech and DOSECC started negotiating a contract early July. At present they are down to arguing about one sentence. We expect to have a contract early next week, and the drill rig mobilized and onsite a few weeks hence.

The drill started turning on Thursday, 16 November. At night you can clearly see the drillsite lighting in the canyon beneath M Mountain. We expected to hit bed rock at 10-20 feet. So far we are down 60 feet and still in mine tailings or landslide material. The tailings are very porous hence need to be cemented. This requires us to stop drilling, fill the hole with cement, and wait for it to set up. When we hit bed rock a casing will be cemented in place and drilling in bed rock will start with a smaller bit than the 6 in size being used at present.

All the drill crew are here. The drill crew and the Tech oversight/logging crew (Jim Witcher, D. Norman, students Lara Owens, Amber McIntosh, and Matt Earthman) took H2S training on Friday. On that same day H2S monitors were installed at the drillsite and emergency respirators were delivered. The chance of encountering H2S is very unlikely. Witness to this is no H2S smell is Socorro Springs water nor any smell the other wells and thermal springs in the Socorro area.

The members of the Tech oversight/logging crew and PPlant personnel that had not received an EMRTC safty briefing did so on Friday. The State was notified that drilling was starting, but did not send a representative.

We finally encountered bed rock at about 80 ft. Drilling was halted on Wed. evening (Nov 22) at about 70 ft. waiting for a replacement drill bit. Earlier that day President Lopez and Van Romero visited the drilling site. The tailings and landslide material being drilled was extremely hard on drill bits. The new bit came in Friday noon. By Saturday the hole was advanced to a depth of 100 ft. Drilling was stopped Sat. to cement and case the hole. We expect to be coring on Wed. and to make much faster progress.

Bedrock entered is tentatively identified as the Madera Fm. At present we are in a rhyolite dike. The drilling mud temperature increase is consistent with geothermal waters at depth and suggests a thermal gradient of at least 12 F/100 ft; a normal gradient is 1.8 F/100ft.

The cold has not slowed operations appreciably. There were minor problems with pipes connections and water lines freezing, but there was no show-stopping
problem. Three new drillers arrived to replace the driller and his brother that returned home to recover from a serious staph infection.

Drilling is now in bedrock. The Madra formation first encountered has swelling clays that slowed drilling. We are now in the Sandia formation at 203 ft. Both formations were predicted in Richard Chamberlain’s cross section and the sediment dip is about 20 degrees, which agrees with Chamberlain's map. At 4 am Sunday morning we had a major loss in circulation that maybe the Sandia Fm fault contact with the Precambrian rocks.

The core shows considerable brecciation. That is good sign that rock at depth is brecciated and can sustain high flow rates of geothermal waters. Sediments show spotty silicification, and there are fractures mineralized with quartz crystals. This mineralization is thought to be from the geothermal event that mineralized the Wood’s Tunnel mine and not related to the present geothermal systems. Fluid inclusion analysis will tell us if this quartz truly is from a past geothermal system.

Dec. 11 finds us still at a depth of about 200 ft. in bad ground. We are in a fault zone in the Sandia Fm with lost drilling fluid circulation. The rock is highly fractured, silicified, vuggy with quartz-filled cavities, and with frequent seams of brown clay that we assume are fault gouge. Attempts to clean the well of hand-sized fragments that slough off well walls failed on Thursday. As fragments were removed others fell into the well. We are now advancing slowly cementing wall rock as we go. Cement takes about 24 hours to set up, hence there is a lot of down time. When the fault zone is crossed casing will be set and we will drill with a smaller diameter bit. This probably will start tomorrow (Tue. Dec 12). The smaller hole is not as likely to fill with fragments, and we will not have to stop drilling if circulation is lost.

Drill core mineralization differs from what we see in Woods Tunnel. The core has no barite, calcite, and sulfide minerals that are common in Woods Tunnel mineralization. Some of the core silica is opal.

Jim Witcher says this is the worst hole he has drilled in his 24 years of drilling experience. He speculates that we may be at the top of the M-Mountain geothermal system and the core mineralization is related the present geothermal system. If so the silica indicates water temperatures at depth > 180 C.

Final Report. (Ed. note: Drilling ended on Dec 19, 2006 at depth of 240 feet.)