Measuring Equipment Design Of Static And Dynamic Contact Angles At High Temperature And High Pressure Conditions

CGS(Carbon Geo-Sequestration) as one of the most promising CO2 emission reduction programs, has attracted extensive attention worldwide. Wettability of supercritical CO2/saline/mineral system affects sequestration mechanism, fluid migration, storage capacity and depth in CGS. However, contact angle as an important parameter to represent wettability, is affected by multitudinous factors and there are large uncertainties with current research results. Accurate descriptions and further investigations on contact angle are required. There are several problems of current experiment apparatus for CO2/saline/rock system contact angle measurement:unable to accurately measure the temperature of contact interface; measure contact angle merely at a single location which is unreasonable to characterize wettability of the whole rock surface; the dynamic contact angles measured with increasing or decreasing liquid droplet volume deviates seriously from the true values. In order to overcome these shortcomings, this dissertation studies the measurements of static and dynamic contact angles at HTHP (high temperature and high pressure) conditions based on the traditional measuring methods of contact angle and ADS A (Axisymmetric Drop Shape Analysis).Based on captive bubble method and ADSA, the measurement of static contact angles has been investigated and related devices were well designed. The minimum wall thickness of double windows HTHP chamber was calculated to be 19.6 mm according to GB4732 to ensure safety. Sapphire windows, screw sealing head, sealing etc were designed to solve illumination inside and improve sealing performance. Temperature adapter includes plug, pressing nut, thermocouple and guard staple, which is to achieve level adjustments and accurately measure temperature of contact interface. Syringe was conceived to measure contact angle of rock surface at different positions with components of needle which was straight or curved, screw barrel, screw handle and needle tube. Finally, accessories were matched perfectly and assembly of equipment were completed successfully.Based on tilting plate method, sessile drop method and ADSA, the measurement of dynamic contact angles has also been studied and related apparatus were designed. The minimum wall thickness of single window HTHP chamber was calculated to be 24.5 mm according to GB4732 to ensure safety. Split ring closures were designed to solve the sealing of device and fiber-optic ring-lights was devised to illuminate interior chamber from one side not interfere in shooting path. Micro-magnetic coupling was innovated to achieve static sealing and transfer momentum, which makes the substrate holder tilted with small angle to measure dynamic contact angle by the designed fixed axis gears system via capturing the bubble motion state. Therefore, it is the key technology of design scheme. NdFeB was selected as permanent magnetic material, optimal magnet number was configured to be 2, micro-bearing was matched deep groove ball bearing 605 of 01 series. Then, magnetic moment meet experimental requirements very well was verified with the equivalent magnetic loading theory. The single window HTHP chamber matches parts interchangeability and assembles accessories above.Measurement technology of static and dynamic contact angles at high temperature and high pressure conditions and related apparatus which were mentioned in this dissertation not only provide significant means for further research wettability of CO2/brine/mineral system in CGS condition, but also enhance data accumulation in the process of supercritical CO2 geological sequestration, which has vital significance to explore the dynamic migration of CO2 in CGS.