济阳坳陷陡坡带砂砾岩体发育特征及油气成藏规律研究

Jiyang depression is one of the most important petroleum production basins in China. The petroleum pools, found easier, have been densely explored and developed. At present, the subtle traps are becoming the main exploring aims. A lot of Tertiary sand-conglomerate body petroleum pools, as one of the important subtle pools, have been discovered recently. It is necessary and urgent to study deeply the developing characteristics and petroleum pool distribution of Tertiary sand-conglomerate bodies in Jiyang Depression. The present dissertation has concluded the main developing characteristics of the Tertiary sand-conglomerate bodies in Jiyang Depression, and studied the sand-conglomerate bodies in Chengnan Fault Zone in detail. Depending on the synthesized studies of geology, geophysics and logging data, the following conclusions have been arrived at. Four criterion layers in Member 3 of Shahejie Formation, according to the depositional cycle analyses, have been established for the subdivision of different layers of sand-conglomerate bodies and the correlation of different sand-conglomerate bodies. It indicated that the alluvial delta, delta-fan, alluvial fan, shallow water fan , deep water turbidite , fan-front turbidite are the six kinds of sand-conglomerate bodies, which have been distinguished in Jiyang Depression with the study of genetic types, characteristics and distribution of sand-conglomerate bodies. The shallow water fan, steep slope deep water turbidite and fan-front turbidite were the main types of sand-conglomerate bodies developed in Chengnan steep slope. Their identification and distribution have been described in detail. The development and distribution of sand-conglomerate bodies were resulted by fault depressing, palco-climate change and channel or trough on the uplift. The fault depressing is the most important-factor to the episodic developing of sand-conglomerate bodies. An episodic developing genetic mode has been established by the contrast analyses between episodic fault depressing and climate change cycles. The hydrocarbon accumulation in the sand-conglomerate bodies in the steep slope was correlated with fan types, depositional phases, fault depressing and diagenesis. Sand-conglomerate wedge out (include up-oblique and onlap), lithological wedge out, mud screen (for anticline), fault plugging (by mud opposite sand, mud daubing) are the 5 possible mechanisms of oil accumulation. Lithological pool, stratigraphic pool and tectonic pool and lithologic-tectonic complex pool, and 9 subtypes of petroleum pools have been detected. It is easy for different pools to be combined as a complex reservoir, which was distributed along the syn-depositional fault slopes. The sand-conglomerate bodies in deep sag were usually evaluated as pore zone for hydrocarbon accumulation before. In fact, they are potential. Because of fan-front turbidite sands were especially developed in these zones, the sands have a close connection with the oil mud, and lithological pools can be expected to find in these zones. Chengnan fault slope was main channel of oil migration, and mud screen is the principle key for the oil accumulation in the sand-conglomerate bodies. If there was no mud between the sand-conglomerate bodies or on the top of sand-conglomerate bodies, the sand-conglomerate bodies would connect each other and there would be no dense material to hold up the oil migration along the slope. As the sand-conglomerate bodies could not been taken as a screen, the mud screen is the key for developing pool in this slope. According to this principle, about 6 potential traps, such as C915 block, C913 block, C916 block, south of Y109 well block, Y104 block and Y153 block, were selected for exploration and development.

抽水引起岩溶塌陷的机理及非线性预测研究

Karst collapse is one of the most important engineering geology hazards in Karst district, which seriously endangers the living of humankind and the environment around us, as well as the natural resources. Generally speaking, there exist three processes of overburden karst collapse:the formation of soil cavity, the expansion of soil cavity and the fall of the cavity roof. During these processes, groundwater is always the most active factor and plays a key role. Pumping will bring into the great change of groundwater in flow state, flowrate, frequency of fluctuation as well as hydraulic gradient and will speed the fall. Statistics shows that most of the man-made karst collapse are induced by pumping, so studying the mechanism of Karst collapse induced by pumping will provide theoretical base for the prediction and precaution of collapse. By theoretically studying the initial condition for the forming and expanding of a soil cavity, Spalling step by step the essential mechanism of Karst collapse induced by pumping is put forward. The catastrophe model for the collapse induced by pumping is set up to predict the fall probability of a cavity roof, and the criterion for the collapse is determined. Simultaneously, Karst collapse induced by pumping is predicted with manmade neural network theory. Finally, the appropriate precaution measurements for the collapse induced by pumping are provided. The creative opinions of the paper is following: The initial condition of forming a soil cavity is put forwarded as formula (4-1-5), (4-1-24),(4-1-25) and (4-1-27); which provide theoretical base for foreclosing the formation of a soil cavity and defending collapse. Spaliing step by step as the essential mechanism of Karst collapse induced by pumping is put forward. The spaliing force is defined as formula (4-2-15). The condition for the expanding of a soil cavity is that spaliing force is greater than tensile strength of soil. The stability of a soil cavity is first studied with catastrophe theory. It is concluded that the process of development up to ground collapse of a small cavity is continuous, however, the process of a big cavity is catastrophic. It is feasibility that the Karst collapse be predicted with manmade neural network theory as a new way.