An Experimental Study on Percolation Characteristics of a Single-PhaseGas in a Low-Permeability Volcanic Reservoir Under High Pressure
In this paper, we find that with the decrease in the average pore pressure in the process of gas production, both the slippage effect and the stress sensitivity effect will gradually increase; the increase in the slippage effect is significant, while the increase in the stress sensitivity effect is not. In this paper, the Kalamay volcanic gas reservoir of the Junggar Basin in China was selected as the object of our research. The gas reservoir has typical fractured volcanic reservoirs, and the long-term percolation feature remains unclear. To study the percolation characteristics of single- phase gas under high pressure, the experimental method was designed to simulate these characteristics in the process of gas production by measuring the gas flow in the core and the input and output pressure at both ends. We carried out simulation experiments of single-phase gas flow percolation characteristics under high pressure using 11 pieces of vol- canic rock samples in three wells of the study area. The results show that as the core pore pressure increased, the per- meability of low-permeability cores of the volcanic rock decreased significantly at room temperature. However, this decrease became more gradual, which means that the higher the core pore pressure is, the smaller the permeability variation caused by gas slippage is; when the pore pressure is above 10 MPa, the permeability is nearly constant, slip- page effect significantly reduces in the process of gas percolation, so it can be completely ignored under these forma- tion conditions. As the pore pressure decreases, the slippage effect and stress sensitivity effect will gradually increase; when the pore pressure is less than 10 MPa, the permeability appears to increase significantly, and this is especially true for a pressure of 5 MPa. The main cause of this result is the slippage effect of gas seepage during the depletion of the gas reservoir, when the pore pressure is lower than a certain value. The valid stress changes of the core are not large, and the stress sensitivity is not strong, so the slippage effect plays a major role, which leads to an increase in the gas permeability during the late period of certain flow gas production.
Hydrocarbon Seepage, Gas Hydrates, and Authigenic Carbonate in the Northwestern Gulf of Mexico
Rapid deposition of organic rich sediments onto thick Jurassic salt deposits created conditions conducive to the formation and entrapment of large volumes of oil and gas as well as active salt diapirism. Resulting hydrocarbon seepage, brine seepage, hydrate formation and decomposition, methane oxidation, oil degradation and authigenic carbonate precipitation have significantly affected the geology, geochemistry and morphology of the continental slope of the northern Gulf of Mexico. Regional topography is largely controlled by salt diapirism and slumping, and is characterised by pock marks, mud volcanoes, disrupted sediments and large accumulations of carbonate. Sediment chemistry is driven by the influx of oil, gas and brine seepage and secondarily altered by the enhanced microbial and benthic biology. See also Abstract No. 89051216.
FUNDAMENTAL STUDY OF GAS SEEPAGE IN ROCK AND OPEN-CRACK
数種の円柱および大型円筒形の岩石供試体を用いた室内透気実験を行い, 乾燥および湿潤状態における透気のパラメータを決定した, その結果. 本実験で用いた岩石の固有浸透係数は, 概ね1×10-19～1×10-15m2の範囲にあった. また, 地下深部を想定した高圧条件下での開口割れ目における漏気条件に関する実験を行い, 水圧および割れ目幅と漏気限界ガス圧の関係を得た.