Abstract
Under the condition of simulated formation temperature and pressure, the compression and shear wave velocity of the tuffaceous conglomerates and rock-fragment sandstones of the reservoirs in K1t, k1n group of Cretaceous system in Tanan are measured. The effects of lithology, mineral content, density, porosity, shale content, and water saturation on the acoustic velocity of the athrogenic rock are studied. Within the limits of our observation, some rules are found: (1) the velocity of the fine tuffaceous conglomerates is remarkably greater than that of the tuffaceous rock-fragment sandstones with good physical property; (2) the compression velocity increases with fragment content, and decreases with quartz and feldspar content in the mud; (3) the compression velocity increases with density, especially, in tuffaceous rock-fragment sandstones, the velocity keeps a good relation with density in form of power function; (4) compression and shear wave velocity decreases with porosity and shale content, velocity of the tuffaceous rock-fragment sandstones keeps a good relation with porosity and shale content in form of negative linear function, but effects of shale content is only 1/5 to 1/10 of that of the porosity, hence can be neglected; (5) with porosity increases, compression wave velocity is relatively sensitive to fluid alternation, and the rang in which velocity varies keeps positive correlation with porosity. The result provides a foundation for the research of seismic and logging data evaluation approaches in athrogenic rock reservoirs, Haita basin.
Highlights
Haita Basin is a part of Central Asia-Ancient Aulacogen, which belongs to Eergu’Na-Greater Khingan Range tectonic zone
Tongbomiao Formation and Nantun Formation in the lower Cretaceous of Zhalainuoer group develop a large number of oil-bearing tight tuffaceous conglomerate and medium to low porosity and permeability rock-fragment sandstone reservoirs, which forms the main area for improving the production and has great po
Schön (1996) [14] did a lot of statistical work on the acoustic velocity data of igneous rock and found that, the compressional wave velocity decreases with the increase of SiO2 in the rock, Khatchikian(1982) [15] combined density, neutron and acoustic logging curves to determine the lithology of igneous rock and calculated the porosity of reservoirs
Summary
Haita Basin is a part of Central Asia-Ancient Aulacogen, which belongs to Eergu’Na-Greater Khingan Range tectonic zone. Due to the lack of adequate understanding of the factors that affect the velocity of the volcano clastic rock in Haita Basin, the seismic and logging data can’t be applied to predict the lithology of rock, calculate the porosity and detect the oil and gas effectively. A detailed research on the influencing factors of velocity in the volcano clastic rock in Haita Basin is needed. The compressional and shear wave velocities of conglomerate and tuffaceous rock-fragment sandstone in Tanan were measured in this paper. The influences of lithology, mineral content, density, porosity, clay content and fluid saturation on the compressional and shear wave velocity are analyzed, which provide the experimental foundation for employing seismic and logging data to predict the lithology, calculate porosity and recognize the fluid type
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