| The deep sea is a huge space connecting the continents of the world,and contains extremely rich strategic mineral resources.It is an important component of the Earth’s life support system.The deep sea rocks record the origin of the Earth’s life,the key information of marine elements,and are important carriers for studying the theory of plate tectonics and revealing the metallogenic mechanism of the oceanic lithosphere.The deep sea is characterized by extreme environments such as high pressure,low temperature,high salinity and darkness,and human understanding of it is even less than that of Mars.Due to the uniqueness and importance of the deep sea,the United States,Japan and European powers have successively carried out a lot of deep sea drilling research in the past 80 years.With the successful application of the "Jiaolong" 7000 meter manned submersible,China began to make efforts after the "12th Five Year Plan",and has developed rapidly in deep sea exploration projects,The fine drilling technology for deep submersibles has become an important means to carry out high-quality resource exploration and development in the extreme deep-sea environment.Compared with land drilling,deep-sea core sampling and exploration are greatly different in operating environment,technical requirements and basic conditions:the high-pressure environment changes the bit structure,and the water resistance environment affects the cutting force and breaking flow field;The fracture behavior of deep-sea rocks is characterized by obvious multi structure,strain softness and non observance of the law of continuum mechanics,which challenges the analysis of drilling mechanism;Due to the requirements of the deep-sea quasi weightlessness environment and the lightweight carrying of the launch vehicle,the drilling pressure available is small,which brings difficulties to efficient drilling.In view of the above problems,systematic research was carried out on the mechanism of efficient drilling with small WOB and refined drilling methods of deep submersibles in deep-sea environment.The drilling characteristics and mechanical properties of deep-sea rocks under low bit weight were analyzed.Based on the physical and mechanical statistics of ocean rocks,the rock mechanics and drillability analysis model is established;Based on the analysis of the cutting force of single diamond,the movement law in the rock cutting process and the drill bit layer change law are obtained,and the dynamic mechanism model of deep-sea rock fragmentation is established.For key parameters such as cut in depth,pressure strength and rock compressive strength,quantitative analysis of key parameters such as penetration rate,weight on bit and power of drilling rig is carried out to obtain the optimal value range,which provides basis for subsequent structural design.The numerical simulation and parameter matching of rock fragmentation behavior based on discrete element particle flow method were carried out.Based on the discrete element particle flow analysis method,the simulation analysis of core coring behavior characteristics is carried out,and the three-dimensional discrete element constitutive model of deep-sea cobalt crusts is established.According to the Hertz Mindlin contact model matching strategy,the particle constitutive matching model of rock discrete elements such as Poisson’s ratio,friction coefficient and shear strength is established.Based on the EDEM discrete element software,a variable constitutive discrete element model with apparent cohesion is established.Through the analysis of drilling and coring characteristics of discrete e lement simulation,the influencing factors of bit structure,speed and bit weight on sampling are obtained.Carry out research on fine core sampling technology for deep-sea vehicles.According to the requirements of deep-sea high-pressure,highly corrosive extreme environment and lightweight load of manned submersible,a high-performance light electric drive integrated coring load test prototype based on Jiaolong was developed through the design of deep-sea pressure compensation,pressure chamber,dynamic and static seals,and a refined drilling system integrated with Jiaolong manned submersible was established;Based on the working condition of low bit weight in deep sea and taking efficient drilling as the design criterion,the configuration design method of dual apex angle coring bits with internal and external double row distributed discrete main and auxiliary cutting edges is proposed,and the optimization of structural parameters of coring bits is completed;For the demand of fine drilling,the system functionality is verified through the connection and adaptation tests of the control,energy and operation between the drilling rig and the Jiaolong manned submersible.Finally,the behavior characteristics of drilling and coring under small WOB load conditions are analyzed and verified by deep-sea tests.Based on the simulation analysis of deep-sea rock cutting model and discrete element modeling,the test carrier of deep-sea drilling load drilling characteristics is constructed,the drilling efficiency test research is carried out for three types of coring bits,and the prediction model of rock cutting crushing load is established;Based on the load behavior characteristics test,the research strategy of test driven model optimization is adopted to improve the drilling mechanical model of broken rock in deep-sea environment,and obtain the value rules of the minimum drilling force,drilling speed and other technical parameters;Based on the kinematics,dynamics and other characteristics of Jiaolong manipulator during bottom sitting operation,a refined operational dynamics model for the interaction between core drilling rig and carrier is established;Finally,relying on the China Ocean Voyage,the Jiaolong drilling system drilling test was carried out in the deep-sea environment to verify the drilling theory and rig performance,providing test method support for centimeter level fine operation and regulation formulation of deep-sea carrier under small bit weight. |
PDF Full Text Request