Geothermal drilling

Geothermal drilling

Temperature logging is based on the assumption that the formation around the wellbore is a thermally stable body, and the natural temperature gradient is caused by thermal diffusion from the Earth. When this thermal equilibrium condition is disrupted, the temperature gradient or radial temperature distribution inside the wellbore will change. Well temperature logging reflects changes in the local temperature anomalies and temperature gradients of the wellbore, and infers possible conditions based on these changes. Hot spring water requires a certain amount of time, process, and specific geographical location changes, and commonly used engineering object detection methods include electrical logging, P-S logging, radioactive logging, borehole television, and borehole photography. Logging is a widely used in-situ testing technique in the engineering field. Through logging, a large number of physical parameters related to the rock and soil properties can be obtained, including the elastic wave velocity, rock and soil mechanics parameters, density, water content, porosity, mineralization, resistivity, well temperature, etc. of the rock and soil layers. It can also be used to determine the diameter, inclination, and sediment at the bottom of the borehole itself. Based on the design well formation prediction and past work experience, requirements are proposed for the key construction points of each well section, and preventive and handling measures are proposed for major accidents and complex situations in the well. Geothermal drilling rigs are mainly selected and used in conjunction with actual equipment conditions based on geological conditions, drilling techniques, and designed wellbore structures. Generally, oil or hydrological well drilling rigs are used, and the principle of selection is that the lifting load should not exceed 80% of the hook load of the drilling rig. The selection of air compressor is mainly based on the required air volume and pressure, and the main specifications and performance of the air compressor should meet the needs of geothermal well construction and well cleaning. After geothermal exploration and before drilling, the drilling type should be determined based on geological conditions, whether it is metamorphic rock, sedimentary rock or igneous rock. In complex areas, comprehensive drilling is also required. This situation often requires not only technical expertise, research and time experience in comprehensive drilling, corresponding mainstream equipment, but also professional management and monitoring systems. When formulating a geothermal well development plan, the first step is to determine the depth of geothermal well drilling, which is also considered based on the survey results and specific conditions.

Geothermal drilling

Drilling is a systematic engineering that involves the joint operation of multiple professions and trades using various equipment, tools, and materials. At the same time, it is a continuous operation with multiple programs closely connected and multiple links interlocked. The entire construction process is quite complex. The completion of each well includes three stages: pre drilling engineering, drilling engineering, and completion operation. Each stage of the project involves a series of construction procedures. The main processes generally include: well positioning, road survey, foundation construction, installation of wellhead, moving, equipment installation, primary drilling, secondary drilling, drilling, lifting, drill bit replacement, drilling, completion, electrical measurement, casing installation, cementing operations, etc. Drilling equipment consists of eight major systems: lifting system, rotating system, circulation system, transmission system, drive system, control system, drilling base, and auxiliary equipment. The lifting system of the drill is equipped with a set of lifting equipment for lifting and lowering the drilling tools, lowering the casing, controlling the drilling pressure, and delivering the drill. The rotating system mainly consists of a winch, auxiliary brake, swimming system, derrick, etc. The main equipment is the rotary table installed on the drilling platform wellhead. When rotating, it drives the drill string and drill bit to rotate and drill through the square drill rod. When using downhole power drilling tools to drive the drill bit to rotate, the turntable is used to withstand the reverse torque.