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Abstract:In north-west Jiangxi, China, most shale-gas exploration has been focused on the Lower Cambrian Hetang and Guanyintang formations, whereas the Upper Ordovician Xinkailing formation shale has been ignored for years due to heavy weathering. This study systematically analyzed gas source conditions, reservoir conditions and gas-bearing ability in order to reveal the shale-gas accumulation conditions of the Xinkailing formation. The results show that the Xinkailing formation is characterized by thick deposition of black shale (10-80 m), high organic content (with total organic carbon between 1.18% and 3.11%, on average greater than 2%), relatively moderate thermal evolution (with vitrinite reflectance between 2.83% and 3.21%), high brittle-mineral content (greater than 40%), abundant nanopores and micro-fractures, very good adsorption ability (adsorption content between 2.12 m 3 /t and 3.47 m 3 /t, on average about 2.50 m 3 /t), and strong sealing ability in the underlying and overlying layers, all of which favor the generation and accumulation of shale gas. The Wuning-Lixi and Jinkou-Zhelin areas of the Xinkailing formation were selected as the most realistic and favorable targets for shale-gas exploration and exploitation. In conclusion, the Wuning area has great potential and can provide a breakthrough in shale gas with further investigation.

The complicated geological conditions will bring great challenges to the drillstring of horizontal wells for the reason that the increase of the well depth in Sichuan-Chongqing region. Since drillstring failure and friction during drilling are generally caused by drillstring vibration, great importance must be attached to computer simulation methods for the prediction of drillstring vibration. A finite element model considering axial, lateral and torsional vibration is established. In order to verify the established numerical model, an indoor experimental device based on the similarity principle was established. The vibration characteristics of three shale gas horizontal wells drillstrings are described. The reasons for the large difference in vibration characteristics between the three wells were discussed by changing the well structure, BHA(bottom hole assembly) and drilling parameters. The simulation results show that the depth of ultra-deep well 3 is only 1.27 times of that of medium-deep well 2, but the fluctuation of WOB (weight on bit) is 2.8 times. The primary factor for the great difference of WOB fluctuation is the change of vertical section depth, the secondary factor is the change of the horizontal section length. Additionally, the reasonable range of speeds has been proposed and applied in the field. The advantage of this numerical analysis method is that it can judge the vibration and friction torque of drillstring in horizontal wells with arbitrary structure, drilling parameters and BHA. This method has certain guiding significance to the field practice.

It includes four aspects that development of science & technology industry promotes construction of ecological mining area: improving recovery ratio of mineral resources, improving resources comprehensive utilization, reducing discharge of wastes in mining area and reducing destruction to ecological environment. It includes five aspects that construction of ecological mining area promotes development of science & technology industry: providing financial support, providing technical support, providing market, providing test sites and production base, providing development direction. To synergetic development of science & technology industry and ecological mining area, the fundamental mechanism is the realization of benefits synergy, target and approach synergy and innovation synergy.