The DESCRAMBLE project has developed novel drilling technologies for a proof-of-concept test of reaching deep geothermal supercritical resources. In the project, we have drilled and tested the continental-crust condition for demonstrating novel drilling techniques, the control of gas emissions and high temperature/pressure conditions expected from the deep fluids. The project has also improved knowledge of deep chemical-physical conditions for predicting and controlling future drilling conditions. The test site has been an existing dry well in Larderello, Italy, already drilled to a depth of 2.2 km and temperature of 350°C, which was deepened to 3 km depth reaching supercritical conditions.
National K Works, which has produced the thermal flask, estimated that the flask can handle up to 550°C for short periods. In addition, the electronics in the tool is set up to measure up to 557°C well temperature and the metal seals are rated up to 650°C. The only components not rated fully to 550°C is the temperature probe which is rated to +500°C and the grease in the pressure tube which is rated to +400°C.
About The Project:
Exploitation of super-critical water from deep geothermal resources can potentially give a 5-10 fold increase in the power output per well. Such an improvement represents a significant reduction in investment costs for deep geothermal energy projects, thus improving their competitiveness. The ongoing European Horizon2020 DESCRAMBLE (Drilling in dEep, Super-CRitical AMBients of continental Europe) project will demonstrate the drilling of a deep geothermal well with super-critical conditions (>374°C, >220 bar) by extending an existing well to a depth of around 3.5km. The drilling operation is depending on verification of the bottom hole pressure and temperature where state-of-the-art electronic logging tools cannot operate reliably. SINTEF has developed a novel pressure and temperature logging tool for this extreme environment. The target specification for the tool is 8 hours logging of temperature and pressure at 450°C and 450 bar.
NASA turned to NKW after having a number of failed attempts to manufacture a manifold block that included 20 very small holes, many intersecting. This complex internal geometry, featuring very small holes and tight positional tolerances, required machining and finishing expertise that was at the edge of current technologies. To further complicate the project, the turn-around time was within a single month.
NKW engineers and machinists created manufacturing drawings and models, constructed a test block for process certification, developed new processes, and then produced four units. NASA’s payload manager subsequently sent a letter of recommendation to other Johnson Space Center departments.
NKW housed a downhole measuring tool that tracked the relief well's bit as it traveled to intercept the original well bore. This was a short turnaround project with demanding technical requirements. This successful project was an example of when it needs to be done right the first time, the customer knew to contact NKW.
Sandia's prototype memory logging tool was specifically designed for geothermal environments to 425°C/800F. The Dewar/pressure vessel utilized for this tool was manufactured by National K Works, Inc. The outer tube constitutes the pressure housing, capable of withstanding up to 700 atm (10,000 psi). A vacuum is established between the outer and inner tubes. This, along with proprietary materials, provides the thermal barrier needed to stand off ambient wellbore temperatures, protected by the Dewar's contents.
After retrieving the data logger and a section of the thermistor string from Hole 858G, the GRC Ultra High Temperature Multi Sensor Memory tool (UHT MSM) from the University of Miami was deployed. The tool's pressure housing was designed and manufactured by NKW, Inc.
Logging results showed sharp temperature increases from bottom-water values at the mudline to approximately 228°C at 9 mbsf and to a maximum temperature of 273°C at 206 mbsf where the tool encountered an obstruction still inside the casing that effectively terminated the run (Figure 3).
This temperature log marked the first ODP in-situ high temperature measurements in a deep marine hydrothermal field. Site observations and the temperature profile suggest that significant amounts of hydrothermal fluids are upflowing through the cased section of the hole.
Vendor-supplied data indicated that armored coaxial cable used by our client would fail at 10,000 psi. To verify the pressure rating, the client tested the armored coaxial cable in our pressure pit. Failure testing began at 2Ksi, and stepped up at 2Ksi intervals: at 30Ksi, the armor still had not failed, proving that much higher pressures were supported. The vendor could recertify their product to a much higher pressure rating, using our empirical data.
A client's FEA indicated that their transmission window design for a downhole logging tool would withstand pressures to 8,000 psi. NKW's engineers proposed a different window configuration that featured three smaller windows, each separated by a narrow arch. We then rapidly prototyped a full scale physical model and pressure tested it in our pressure lab. The windows held at 20Ksi, proving NKW's innovative design; and, enabling the client to implement an attractive solution/capability as a new tool product.