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The Relationship Between The Mechanism Of Abnomal Pressure Formation And Hydrocarbon Generation And Entrapment In The Dongying Depression

Posted on:2011-10-07Degree:DoctorType:Dissertation
Country:ChinaCandidate:S C ZhangFull Text:PDF
GTID:1100360308990110Subject:Geological Resources and Geological Engineering
Abstract/Summary:PDF Full Text Request
On the basis of previous study and underground data, the forming mechanisms of abnormally high pressures are studied. It is concluded that the undercompaction, hydrocarbon generation and stratum denudation are obviously effective to fluid pressure buildup. Because of the episodic difference, the hydrocarbon generation and stratum denudation are the main factors influencing oil-gas migration. On the basis of basin evolutionary analysis in the Dongying Depression, it is considered that the undercompaction mainly caused the abnormal pressure before the first denudation by the uplift in Late Paleogene, while hydrocarbon generation was the main factor of abnormal pressure after the denudation. The second denudation occurred in Late Neogene, which changed the pressure field and induced fluid migration.Open- and closed-system simulation experiments were made to study the influence of pressure to hydrocarbon generation quantitatively. In conjunction with the analysis by the founded numerical model, some conclusions were made on the basis of the experiments. Pressure suppresses the hydrocarbon generation on different extents according to different source rocks and different evolutionary stages. The higher the hydrocarbon generation potential of mother materials, the higher the evolutionary degree and the higher formation pressures, the more evident the suppression of hydrocarbon generation. The kinetic parameters of hydrocarbon generation of the source rocks related to pressure were accordingly determined.Oil-gas migration experiments were performed with two kinds of media, i.e. filled sands and cores. Pressure difference was obtained to control the dynamic conditions. Pressure prior to drive water when increases. Oil becomes more and more abundant in reservoir gradually. Oil begins to migrate when its saturation get to certain extents. The mixture of oil, gas and water was expelled rapidly during pressure relief because of the existence of gas. Pressure relief makes it easy for petroleum to migrate with the existence of gas.The exess pressure fields were analyzed at critical geologic times. The present reservoirs distribute along excess pressure decreasing directions. The distribution of reservoirs is successional to the evolution of excess pressure. The development of fluid pressure affects reservoir formation as a whole, while oil-gas migration and accumulation affect the distribution of fluid pressure fields. Due to the equilibrium between pressure buildup and pressure relief, fluid pressure created different conditions in various pressure systems during its transference, which caused the differences in types and features of oil-gas reservoirs. Based on the evolutionary history of excess pressure, the reservoir forming process in the Dongying Depression was analyzed. Reservoir formation strongly correlated with tectonic activity at different stages. Oil and gas charged reservoirs to increase saturation at the stage in which pressure rises caused by hydrocarbon generation. The reservoirs were regulated during denudation.
Keywords/Search Tags:Dongying Depression, abnormally high pressure, hydrocarbon and reservoir formation, simulation experiment, oil-gas migration
PDF Full Text Request
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