Analyzing the mid-low porosity sandstone dry frame in central Sichuan based on effective medium theory

Abstract

Tight gas sandstone reservoirs in Guang'an are characterized by wide distribution and low abundance. Sandstone samples from this area usually have low porosity and poor connectivity. We analyze the observed velocity data of tight sandstone samples with the MoriTanaka model, and give the sandstone framework physical model in this area based on theory and experiment analysis. The matrix modulus was obtained by an empirical relationship and then the experiment data were compared with the values predicted by the Mori-Tanaka model with different pore shapes. The results revealed that the experiment data were close to the model with low pore aspect ratio. Considering the matrix modulus and pore shape variation, we find that, under the condition of small mineral composition change, the effective pore aspect ratio of these samples increased with porosity evidently.

Estimation of the Squirt-Flow Length Based on Crack Properties in Tight Sandstones

“…The rock samples were processed into cylinders with a diameter of 25 mm and a height of 25 to 50 mm, and both ends of the sample were polished. The experimental set-up consists of a pulse generator, a temperature control unit, a confining pressure control unit, a pore pressure control unit, and an acoustic wave test unit [54,55].…”

“…Some water-saturated tight samples show a greater S velocity than the gas-saturated state, which is related to the heterogeneous 2 Lithosphere microcracks and microstructures. For tight rocks, the stiffening effect of local fluid flow on rock skeleton, which is induced by S-waves at high frequencies, may also lead to a higher S-wave velocity at the water-saturated state [55]. In the low-pressure range, the rate of velocity variation with pressure is significant and then decreases with increasing 3 Lithosphere pressure (e.g., [18,57], and [58]).…”

A New Anelasticity Model for Wave Propagation in Partially Saturated Rocks

“…A thin section is shown in Figure 5. The experimental set-up consisted of a pulse generator, a temperature control unit, a confining pressure control unit, a pore pressure control unit, and an ultrasonic wave test unit [46,47]. The piezoelectric ultrasonic wave transducers were glued to the top and bottom of the sample, sealed with a rubber sleeve.…”

Microcrack Porosity Estimation Based on Rock Physics Templates: A Case Study in Sichuan Basin, China

“…The development of society has led to a significant increase in the demand of oil and gas resources, and the depletion of conventional petroleum resources made the exploration and extraction of unconventional hydrocarbon resources necessary [1,2]. Tight sandstone reservoirs are widely distributed and account for a high production of China's total natural gas [3,4].…”