Simulations, Optimisation and Testing experiments
The proposed developments are based on the optimization of three major processes in which the partners have recognized field, experimental and numerical modelling skills.
- The modification of the bottom-hole wall-rock to be in a stress state offering least resistance to the dynamic action of percussion drilling. This will be investigated by varying the bottom-hole geometry with slots to ease confinement, create free surfaces and counter the rock strengthening effect associated with the increased mean stress with depth.
- The rock destruction during slotting of single or multi- grooves on the bottom-hole using a High-Pressure Water Jet. Optimal jetting conditions to create the desired grooves will be determined for different in-situ conditions and hard rock properties.
- The rock destruction and drill response during hammer-bit-rock interactions of the percussive drill. Optimal operating conditions will be determined to derive the maximum benefit from the modified bottom-hole stress states for different in-situ conditions and hard rock properties.
Principle of the stress release process
Experimental drilling benches at Armines drilling laboratory
Unique in Europe due to the diversity and complexity of its experimental devices, this laboratory of ARMINES- MINES ParisTech Geosciences Research Center located in Pau/South of France is an essential tool for research and development programs in the field of drilling. Its devices are increasingly being extended to new challenges linked mainly to the great difficulties of drilling very hard and very deep rocks and controlling the trajectories of wells in these geological contexts. More efficient methods of cutting hard and abrasive rocks under high confinement are sought and evaluated (adaptation of the percussive process to deep drilling conditions, stresses relaxation process on the bottom hole, assisted drilling with high pressure water jets, drilling by pulsed electric discharges, sonic drilling, etc.).
To date, it is the only independent laboratory of this size worldwide with the following major equipment:
Single Cutter Testers of Insert impact, under high pressures (100 MPa confining pressure), equipped with high-speed camera.
Drilling bench for testing drilling bits (rotary and percussive) at full diameter (up to 12’1/4) under realistic down hole pressures (up to 5000 m depth) and drilling parameters (20 tons WOB, 1000 RPM, all types of drilling mud). Fully instrumented to monitor the drilling process (ROP, directional behaviour, vibrations, wear, lifetime of the equipment, etc.).
Horizontal drilling bench for testing a whole drilling system up to 20 meters long, able to drill 7 meters hole length in hard rock with any type of drilling bits (rotary and percussive) and any drilling modes (sliding, double rotations, directional, …). Drilling parameters: 20 tons WOB, 250 RPM, 600 l/min flow rate of any types of drilling mud.
Quite adapted to test the mechanical integrity of a given drilling assembly and to measure its drilling behaviour and efficiencies (ROP, vibrations, ….).
High Pressure Water Jets benches to tests performances of submerged nozzle using pressure sensor coupled with 3D robot allowing to measure the pressure profile at a given distance from the nozzle, rock slotting performances of a submerged High Pressure Water Jets.
Software used by the Imperial College London team is based on the two versatile software platforms created at Imperial, Solidity which handles the solids and a combination of both Fluidity / IC-FERST which handles the inertia-dominated or porous media multiphase flow of fluids. The most exciting applications often involve coupling the two solvers to examine fluid structure interactions, such as a water-jet breaking into a sandstone rock. An example of such work is described in the reference:
Xiang, J., Latham, J.-P., & Pain, C. (2019, August 28). Numerical Simulation of Rock Erosion Performance of a High-Speed Water Jet Using an Immersed Body Method. American Rock Mechanics Association. In 53rd US Rock Mechanics/Geomechanics Symposium. Brooklyn, New York. ARMA-2019-1947. Xiang et al ARMA-2019-1947
UPRC is the Lead Beneficiary of Work Package number 3, titled as “Environmental and social sustainability”. The premier task (Task 3.1) of this package is the preparation of an Environmental Impact Assessment (EIA). This assessment may include sections on Risk Analysis (RA), Life Cycle Analysis (LCA), Carbon Footprint (CF), and Ecological Footprint Analysis (EFA), which will be employed on a need basis to quantify selected impacts. Various tools will be assessed for the implementation of this task including openLCA, SimaPro, etc., as well as relevant databases. Task 3.2 includes a Social Impact Assessment which will also include an online survey. The tools that will be used for the implementation of this task include commercial statistical software for the analysis of social acceptance, such as SPSS and Minitab, as well as open statistical software including gretl (Gnu Regression, Econometrics and Time-series Library) and R (R project for statistical computing). Task 3.3 is an energy security implications study, while Task 3.4 will provide a geopolitical perspective through expert interviews. The tools which will be used for the implementation of this task include public data (i.e. publicly available, not personal) and confidential data reflecting expert opinions.