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Deep Geothermal Energy pictogram

Deep geothermal energy

Deep geothermal energy, or high and low energy geothermal energy, for energy needs on an industrial scale.

Feasibility study


Low energy

This first step allows our customers to validate the development potential of this renewable energy and to have decision support tools to pursue this type of virtuous and profitable investment. It is also integrated during the establishment of an energy master plan. To facilitate this decision-making, we proceed along a precise path:

  • State of play
  • Geological and hydrogeological context
  • Qualification of the resource and the valuation method
  • Adequacy resource / needs
  • Identification of the different possible scenarios
  • Regulatory approach

High energy

In the same way, the stages of a pre-feasibility in HE proceed as follows:

  • State of play
  • Exploration of fields by indirect method (geology, geophysics, geochemistry)
  • Qualification of the resource and valuation perspectives
  • Identification of the different valuation methods
  • Regulatory approach


The feasibility study builds on the conclusions of the opportunity study to deepen the following elements:


  • Search for the most suitable scenario
  • Operating characteristics
  • Sizing of structures and equipment
  • Estimation of investment and operating costs
  • Risk Assessment

The quality level provided by CFG in the production of feasibility studies is ultimately at the level expected at the preliminary design stage of a project management mission. The study is a real decision-making tool for our clients who can commit themselves calmly in the pursuit of their investment.

Project management and drilling supervision

The CFG teams carry out the “underground” mission in coordination with the “surface” design office, which is responsible for project management of the production and distribution of the energy produced. This joint approach under the guidance of our project managers is a guarantee of quality and ensures the adequacy of needs and resources by using this proven method in geothermal low and high energy and is applicable to hydrotherapy.

Project management is typically composed of interdependent phases according to a classical sequence of phases: Preliminary design, Detailed Design, Bid, Contracting, Supervision, Commissioning. During design phases, CFG intervenes in different areas.

Reservoir engineering

Under the guidance of the project manager, our team of specialized hydrogeologists carries out in-depth technical studies on the following points:

  • Hydrogeological impact studies
  • Modeling of thermodynamic interactions
  • Simulation of the long-term behavior of the reservoir (risk of interference)
  • Detailed analysis of environmental impacts


reservoir engineering with modelisation

Well design

In collaboration with our hydrogeologists and based on their studies, CFG’s drilling engineers define the technical details of well design:

  • Predictive geological section and hydrogeological context
  • Dimensioning of the works: diameter of the casings and the drilling of the reservoir, thickness of the casings, architecture of the works, technical cut of the wells
  • Trajectories (azimuths, inclinations, kick-off point, etc.) and diversion program
  • Materials to be implemented and their impact on the durability of structures
  • Drilling program (drilling, logging, mud, cementing, mud-logging, …)
  • Sampling program of cuttings
  • Logging program
  • Drilling site layout plan
  • Development and testing program

To strengthen the technical and financial control of a drilling operation, since 2016 CFG has acquired a drilling software to optimize technical choices and minimize operational risks:

  • Sizing of the drilling workshop
  • Optimization of tools and drill string
  • Optimization of the equipment used (centralizers …)
  • Identification of friction / wear zones

It makes it possible to rationalize the tools to be implemented and to increase the drilling performances, to improve the work conditions and to increase the durability of the works by limiting the points of weakness while facilitating the decision-making process. In order to lower the risks.

In fine, it contributes to the continuous improvement of our methods and increases the feedback of experience by the analysis of the lived experience by participating in the improvement of conception and realization of the future works.
WellScan software

Design of the geothermal loop

Our fluid and process engineers realize the definition of the equipment of production and reinjection especially with Low Energy (BE):


  • The pumping equipment of the production well, including the submersible electric pump unit and the raising column
  • The surface reinjection pump
  • The equipment needed to protect the geothermal loop against corrosion including the continuous downhole treatment tube (TCTFP) and the treatment plant containing the corrosion inhibitor product (as well as the connection tube connecting the two)
  • Well instrumentation
  • Wellheads


geothermal loop design


Regulatory files

Throughout the life of a project, we carry out on behalf of our customers the setting up of the regulatory files related to the underground legislation of the area in question (eg mining code for France …) and ensure communication with the official regulatory services to define the best drafting and its acceptance.

  • PER (Exclusive Research Scout for a Geothermal Deposit)
  • DOTEX (Opening and Works Permit)
  • PEX (Exploitation License), requests for concessions,
  • DAOTM (Opening Authorization File for Mining Works)
  • Short and Long Term Warranty Applications (SAF-Environment)
  • Mutations, leasing
  • Application for temporary authorization of discharges into the sewerage system
  • Notices and associated environmental impact assessment

regulatory file

Financial engineering

financial engineering
CFG performs a detailed technical-economic analysis of the project and examines the profitability of the operation. He actively participates in the search for financing and / or subsidies and the legal editing of the operation.

Consulting and selection of companies

The study phase ends with the drafting of the detailed program of works (civil engineering, drilling and well testing programs, health and safety documents) as well as the sizing of equipment. On this basis, specialized companies are invited to respond to a call for tenders. Our project team carries out this phase “DCE” through the following stages:

  • Inventory of companies present on the market (sourcing)
  • Drafting of the business consultation file
  • Examination and selection of applications, analysis of offers
  • Writing of the comparison report of the offer and synthesis
  • Preparation of works contract documents

Drilling supervision

Our teams supervise the drilling works whatever the mode of contracting chosen:

  • Visa of execution studies carried out by companies
  • Site preparation and approval of the work schedule
  • Direction and monitoring of works (drilling, testing, equipment)
  • Work execution visa
  • Organization of pre-start meetings (DWOP – Drilling Work On Paper)
  • Supervision of works
  • Assistance to the client for the reception of works
  • Tests and validation of technical performances
  • Final sizing of pumping equipment
  • Organization of pre-reception operations
  • Follow up of reservations until they are lifted
  • Final general count

drilling supervision

Completion and Maintenance of Equipment (GER)

CFG supplies and installs the equipment necessary for the geothermal loop operations:

  • Submerged Electropump Group (GEI)

Our technicians assemble and set up the GEI with the pumping column and fittings necessary for assembly up to the wellhead

  • Station and treatment tube

CFG has developed, markets and installs a reliable system to inject a corrosion inhibitor product at the bottom of the well. A treatment station, equipped with a product storage tank on a holding tank and a regulated metering pump via a dedicated electrical cabinet, injects the inhibiting product through a continuous downhole treatment tube (TCTFP). to the hoof of the production well.

 The TCTFP is the most efficient equipment on the market due to:
– Of a small section
– Exemplary mechanical hold
– A range of coatings to adapt to well conditions (adhesions)
– Continuity guaranteeing the integrity of the device

  •  Wellhead

CFG designs, supplies and installs the various elements that make up the well and injector wellheads, such as spools, master valves, gate valves …

  • The means of CFG

CFG has a secure room with a stock of spare parts to meet the urgent demands of geothermal loop operators. This room also allows storage of critical spare parts on behalf of operators (TCTFP, GEI …).

In addition, CFG technicians specialized in this type of intervention implement:
– Mobile units for work interventions
– Underwater pump group maneuvering platforms and treatment tubes
– Security equipment to ensure the safety of property and people

They also use specialized subcontractors who are trained in equipment installations (crane operator, welder, guardian, etc.).

The safety of our interventions is a priority.

Operation monitoring


The evolution of the chemical composition of the water and its physicochemical properties is likely to reflect any evolution and / or disturbance of the geothermal reservoir, as well as its production equipment, including casings and rotating equipment or not.

Regular monitoring also makes it possible to monitor the effectiveness of the anti-corrosion treatment in place and to take any preventive or corrective action against reactions likely to disturb the operation of wells and surface equipment of the geothermal loop, For example :

  • the development of bacterial colonies,
  • the development of deposits,
  • degassing erosion,
  • corrosion phenomena.

Our interventions are carried out from a mobile unit in which all the sampling and analysis equipment is installed.

All samples taken requiring extensive analysis in a specialized laboratory are sent to BRGM laboratories (or other competent laboratory). They are among the few laboratories in France with the skills and technical abilities to analyze highly mineralized waters with reliability and the limits of detections required.

The BRGM has a unique set of analytical and experimental resources such as chemical analysis, isotope geochemistry, mineralogy, environmental sampling and metrology, microbiology and molecular biology, multi-scale biogeochemical experimentation, treatment processes.




Auscultation diagnosis

The purpose of this mission is to evaluate the level and the evolution of the productivity and the injectivity of the wells constituting the doublet. The aim is to carry out an early and reliable diagnosis of anomalies (leaks, deposits formation, performance losses, etc.) likely to disturb the exploitation. It must make it possible to define the operating conditions of the production and injection pumps. It should make it possible to specify, where appropriate, the recommendations intended to improve the operation from the technical point of view. All of these checks meet the regulatory requirements of the operating license. The different control points are:

  • Dewatering pumping group (GEI)
  • The reinjection pumping group
  • Heat exchangers
  • Wellheads
  • In situ measurement equipment

Our specialized technicians operate from a mobile unit in which the measurement equipment is verified and calibrated according to the metrology standards.


Integrity control (TCTFP)

CFG also checks the integrity of the downhole treatment line and ensures the proper functioning of the treatment plant whose maintenance and adjustment of the distributed corrosion inhibitor treatment is carried out by the operator .

Well integrity control by tracing

control by tracing - well integrityIn case of suspected loss of integrity and in addition to logging, the integrity of a structure can be controlled by the fluorescein buffer fresh water tracing method developed by CFG.

In the presence of a leaking casing it settles in the well a circulation between the tank and the fugitive level. A precise control of the volumes of water injected and then disgorged allows to confirm or not the presence of a leak and in some cases to specify the coast.

The method that does not require heavy means and is not intrusive, is to inject a known volume of fresh water with a dye buffer at its base and then, after a waiting time, to disgorge the well. measuring the volume, conductivity and temperature of the product fluid. (for more details, contact us).

Our specialized technician operates from a mobile unit and a skid pumping unit.


High temperature sampling

High temperature samplingCFG is equipped with a specific equipment and a methodology to perform fluid sampling at high temperature in order to characterize – while preserving their integrity – all the components of the fluid, water, steam, gas up to laboratory analysis. This equipment is transported in situ via the geochemical mobile unit to carry out the sampling safely and according to the international standards in force.


loggingOur teams advise beforehand on the tools to implement.

  • Open hole measurements (porosity, resistivity, wall imaging, …)
  • Cased hole measurements (diametric, cementation control, electromagnetic scanner, camera, …)

CFG ensures the coordination of the operators of the operation (logging company, lifting, operator) and the realization of the measurements in the rules of the art. CFG performs the data processing and measurement analysis to alert the operator of any defects found and to advise on the follow-up in terms of additional diagnosis and / or repair to be implemented.

Advice on exploitation, additional diagnosis

Beyond the requirements of the operating permits requiring a certain number of geochemical and hydrodynamic controls, our experience feedback of 30 years in the exploitation follow-up of more than 25 production sites enables us to come to the aid of the operators by giving advice on certain operating variables or offering in-depth diagnostics in the event of an anomaly.

Geoconfiance 2.0 customer platform

CFG has developed a web platform allowing 3 precise actions totally dematerialized:

  • The provision of regulatory monitoring reports (for download)
  • Planning of regulatory follow-up visits (with validation and recall circuit)
  • The exploitation recommendations following the conclusions of our follow-ups (with validation circuit)

Each user has his own login and has access to the scope of visualization and action defined by our administrator.

Link : https://cfg-geoconfiance.fr/login



In order to extend the operating life of geothermal loops, or to solve a problem inherent to a damaged or obstructed well, CFG proposes a diagnosis and proposes ways to rehabilitate the structure. Different types of missions are possible:

  • Unclogging / cleaning
  • Rechemising (steel or composite)
  • repechage
  • Deepening of the pumping chamber
  • Extraction / replacement of strainers / refaction of filter beds
  • Clogging leak
  • Side track
  • Re-entry

Among the innovations put in place by CFG, the use of the composite for the rechemisage of a well.



Well development or remediation

CFG proposes methods of development or remediation of geothermal loops in two different zones:

  • Well with mild acidification
  • Near acidification well or radial jetting


Wells abortWells at the end of their life require sealing in accordance with the directives of the Mining Code. This so-called “abandonment” operation aims to guarantee the absence of risk of damage to the environment over the long term by ensuring the watertightness of the structure and the absence of vertical communications on the extrados of the casings. CFG ensures a complete project management mission of this operation until the restitution of the work to the state and the obtaining of the “discharge” freeing the master of work of its obligations under the Mining Code.

You are interested in our services, do not hesitate:

You are interested in our services, do not hesitate: