Zhiqiang He

To maintain the in-situ temperature of rock cores, a specialized coring device equipped with temperature-preserved module is essential. The thermal insulation material with low thermal conductivity and high compressive strength is a critical component. In this study, an innovative foaming agent was utilized to fabricate an epoxy resin-based insulation material. Nanosilica particles were synthesized via the sol-gel method, followed by the preparation of porous SiO2 microspheres using the polymer-induced colloid aggregation method. The porous SiO2 microspheres were combined with the chemical blowing agent to create a composite blowing agent. Using high strength epoxy resin as the matrix, the study examined the effects of the foaming process and blowing agent content on the properties of the resulting epoxy foam materials.

With the increasing mining depth of deep mineral resources, the underground temperature and pressure also increase, which requires more advanced mining equipment. Therefore, to adapt to the special application scenario of the research and development of pressure-preserving coring tools under the extreme environmental conditions of deep strata, in this study, an in-situ simulation device under high-temperature and ultrahigh-pressure conditions is developed. The principles and methods of applying temperature and pressure to the device are expounded. Furthermore, the two main modules of the device are analyzed and studied experimentally. On the one hand, a segmented simulated coring test cabin is constructed, and pressure testing of the test cabin is carried out. The results show that the test cabin with inner diameters of 150 mm and 500 mm runs stably under the working condition of a pressure up to 190 MPa (considering the influence of temperature of 150 °C), and the cabin remains in the stage of elastic deformation. There is no leakage of pressure or fluid in the whole test process. On the other hand, the performance of the driving module is tested. The results show that the driving module can provide a stable rotation speed of up to 150 r/min when the sealing pressure is 140 MPa. Therefore, the device can be applied to carry out simulated coring test and is suitable for the research and development of pressure-preserving coring tools in deep extreme environments, which may promote the development of deep mining engineering.

Intelligent drilling technologies, such as downhole signal and power transmission, can be used to measure key downhole data and obtain thermal insulation cores. This technology is of great significance for the accurate assessment of deep oil and gas resources, the reconstruction of oil and gas resource extraction systems, and the realization of efficient, intelligent and safe resource extraction. In order to meet the needs of underground communication and power supply for active thermal insulation coring, a new type of conductive center pole was innovatively designed. Using the theory of innovation problem solving (TRIZ) and axiomatic design (AD) to analyze the functional requirements of the conductive central pole, establish and solve the original design matrix. Based on the axiomatic design theory, the non-coupling matrix is decoupled by using the TRIZ solving tool, and the key indicators of the design scheme that meet the independent axiom are evaluated. In view of the contradictions and conflicts, the TRIZ solution tool was continually used to solve, optimize and obtain a design scheme with a higher comprehensive evaluation. Thus, the self-adaptive non-winding connection and power conduction of the conductive center pole was realized. Finally, the strength of the newly designed center pole was checked, and a physical prototype was made. Pre-research experiments on its conductivity and electrothermal conversion efficiency were carried out under different simulation environments to verify its conductivity. It provides innovative solutions to related problems in the field of deep insulation coring and intelligent drilling and provides effective technical means for related needs.

Deep earth science is the basic of deep resource exploitation, and the research on the physical and mechanical characteristics of deep rock is a research hotspot at present. In order to study the physical characteristics of deep rock at different depths, based on the cores at different depths of 4900-6830 m in Songke Well 2 (SK-2), Songliao Basin, this paper carried out the study including the rock characteristics of mineral, wave velocity, density, and pore, the variation law of physical characteristics of deep rock with depth is studied, and the relationship between different physical parameters of deep rocks is explored. It is found that the core composition minerals of SK-2 at the depth of 4900-6830 m vary greatly with the depth, in which the quality of hard phase minerals accounts for a large proportion. After entering the basement stratum, the mineral content of different phases tends to be close. With the increase of depth, the wave velocity, density, and dynamic elastic modulus of rocks show a linear increase trend, and there is a positive correlation between density and wave velocity. In the range of 4900-6830 m depth, the porosity generally shows a downward trend with the increase of depth. In the range of 6000-6830 m, the porosity tends to be close to 7% with the increase of depth, indicating that formation compaction has little impact on the development of igneous pores in this formation. There is a negative correlation between wave velocity and porosity, and the empirical formula is fitted. This study can provide a reference for the exploration of deep geoscience and deep engineering practice.

To establish in-situ fluidized coal mining technology and a theory of mining mechanics for deep coal resources, it is crucial to obtain a fidelity rock core that maintains deep in-situ conditions to understand the physical mechanics of deep rock. Doing so requires the development of in-situ condition-preserved coring (ICP-coring) technology. In this work, hollow glass microsphere/epoxy resin (HGM/EP) composite insulation materials with high strengths were prepared. An epoxy resin matrix with high strength and high-temperature resistance was selected from among epoxy resins cured by different curing agents. Then, a series of composite insulation materials with different HGM volume fractions were prepared. The mechanical strengths of the composites decreased with increasing HGM volume fraction. Then, thermal insulation materials suitable for different ICP-coring depths were selected. Changes in the thermal conductivities and mechanical strengths of the composites were characterized after they were subjected to high water pressure (45MPa). Verification of the applicability of the thermal insulation material under high water pressure (45MPa) conditions demonstrated that it met the working requirements for the ICP-coring device.