A review of geophysical methods for geothermal explorationArticle

• Apr 2015
• Renewable and Sustainable Energy Reviews
• Janvier Domra Kana
• Noël Djongyang
• Raidandi Danwe
• [...]
• Abdouramani Dadje

Exploration of geothermal resources is important from the energy point of view. Geophysical methods are among the three main disciplines applied on the surface to explore geothermal resources, including geology and the chemistry of thermal fluids. This paper presents various geophysical methods of exploring geothermal

Hello Mr. Guillermo,

Thank you so much for the recommendation. This paper could really be helpful. I have come across a recent method of drilling, named " Electric Impulse Drilling/Technology". I am looking for similar methods which can improve cost competitiveness of geothermal or any method which improves upon the exploration methods for geothermal in the initial phases of resourse scouting.

Good question

Look to the fracking an horizontal drilling esperience. the main issue, however is resource. Geothermal energy has been around for a long time and has seen no efficiency gains for over 30 years, unlike wind and solar. It probably wont see them and remain expensive. As each site is unique, it will not gain from mass production gains seen in wind and solar.

Hello Mr. Thomas,

Thank you for your suggestion.

When you say horizontal drilling you mean the "Enhanced/Engineered Geothermal Systems"? Where heat from hot dry rocks is utilised. I have come across some of the papers where EGS is termed as next frontier in geothermal and it is stated that with EGS the wide availability of geothermal will be possible as hot dry rocks are almost always avialable at deep enough depths. But the issue is drilling costs and ecological impacts.

Unfortunately, you cannot get away with drilling for geothermal energy. Unfortunately too, drilling still uses 'classical' methods, e.g., rotary drilling. Sure, there have been improvements in bit and BHA technology and design but they still rely on scraping, crushing, and pulverizing the rocks. There is thermal spallation, laser drilling, and another old reliable - hammer drilling; these technologies still have some years before it can gain acceptance. In the meantime, the drilling industry (as far as I am aware) has focused on upgrading current technologies and business practices on three fronts: the drilling rig operations and maintenance efficiencies, well engineering drilling practices and effectiveness, and the contract's commercial aspects. Right now, there are several fora related to deep drilling (Japan, Iceland, EU, possibly some more) intended to broaden the knowledge and gain industry acceptance in EGS. These groups have made some advances in the drilling aspect but as yet not much on inter-well technology so we just have to be patient.

The drilling cost is significantly impacted by its well design or casing size. Big hole or standard hole is much expensive than slimhole. In the exploration phase, where the drilling objective is more on proving resource or delineate geothermal resource boundary, some suggest to utilize slimhole drilling instead of standard hole or big hole to minimize the cost. It makes sense since the resource uncertainty level is still very high. We recently wrote a conference paper on comparison between those wells, including the cost.

Regarding geothermal drilling cost, based on my experiences, I think the cost is getting higher when you use several special methods or technologies in your operation such as aerated drilling and directional drilling. The utilization of special additives for mud and cement will also bring the cost up.

In addition, stuck pipe risk in geothermal drilling is quite high since it deals with severe lost circulation, especially in the exploration phase. The cost of “lost in hole”, “fishing” and “side track” due to stuck pipe incident is very high so if we can come up with a method or technology to properly plan a stuck pipe prevention strategy, I think it will help in reducing costs of geothermal exploration drilling.

Hello Mr. Romerico Coloso Gonzalez,

Thank you so much for your response. As you mentioned I also came across similar incremental improvements in drilling techniques. Also I came to know that there has been quite an activity in EGS develeopement in different countries and which is being backed by the number of patents being filed in EGS. But again as you said it will take time before there is wide acceptance of EGS or other inter-well technology.

Hello Mr. Dorman Purba,

Thank you so much for your answer. I will be very much interested to know more about the conference paper you wrote about cost analysis and comparison among different drilling techniques.

Can you recommend me any review or conference paper on aerated drilling and directional drilling? I have not heard about aerated drilling before.

As you mentioned, stuck pipe risk in geothermal drilling is quite high, so is this problem mainly faced by slimhole or standard hole drilling? or even big hole drilling?

Thank you everyone for your answers.

I am sharing a link with you titled "IEA-Geothermal-Drilling-Technologies" which I thought was interesting, I am curious to know what do you think about this paper.

http://iea-gia.org/wp-content/uploads/2014/10/IEA-Geothermal-Drilling-Technologies.pdf

Thank you Mr. Vaibhav Gundre,

You may find our recent paper on comparison between slimhole, standard well and big hole via link below:

Conference Paper Basic Considerations in Minimizing the Uncertainty During De...

An article that I would recommend on aerated drilling:

Article Aerated drilling cutting transport analysis in geothermal well

Stuck pipe is main problem in geothermal drilling, for all type of wells, especially when entering the reservoir zone where total lost circulation most likely will happen.

Below are two papers that might be useful:

Conference Paper Drilling Parameter Analysis in Solving Pipe Sticking in a To...

Conference Paper Drilling Problems Mitigation in Geothermal Environment, Case...

Thank you Mr. Dorman Purba,

These suggestions will be greatly helpful for me.