Pore Structure Characterization of Clay Minerals in the Lower Karamay Formation Conglomerate Reservoir in the Junggar Basin and its Impact on Hydrocarbon Storage and Seepage

Abstract

The micro-nano pore structure of conglomerate in the Lower Karamay Formation of the Xinjiang Oilfield, Junggar Basin, northern China is characterized to predict its impact on fluid reserves and seepage. Authigenic clay minerals are mainly kaolinite (67%), followed by an illite/smectite mixed layer (18%), illite (10%), and chlorite (5%). For kaolinite, pore throats between 0-200 nm are dominant, accounting for 90% of the total pore throats. For illite/smectite mixed layer, pore throats also between 0-200 nm account for nearly 80%, while pore throats between 200-500 nm only account for 15%. For illite, pore throats below 100 nm account for about 80%, while pore throats in the range of 100-500 nm only account for 20%. For chlorite, most throats are below 200 nm. The pore roundness of illite is the highest, while the pore roundness of chlorite is relatively lower. The lower limits of the dynamic and static pore throat radii are 42.128 nm and 72.42 nm, respectively. The theoretical contribution rates of the illite/smectite mixed layer, kaolinite, illite and chlorite to storage/ seepage are 60%/45.86%, 52.72%/38.18%, 37.07%/28.78% and 32.97%/26.3%, respectively. Therefore, the contribution rates of clay minerals in the study area are as follows: illite/smectite mixed layer, kaolinite, illite and chlorite.

Influence of Acid Treatment on Pore Structure and Fractal Characterization of a Tight Sandstone: A Case Study from Wudun Sag, Dunhuang Basin

“…The pore structure is a key factor that leads to the poor physical properties of tight sandstones (Abitkazy et al, 2021;Muhammad et al, 2021). Therefore, a quantitative method to evaluate the complexity and heterogeneity of pore structures is necessary.…”

Characterizing the Microscopic Anisotropic Permeabilities of Tight Oil Reservoirs Impacted by Heterogeneous Minerals

“…Two-dimensional porosity can be quickly determined by means of microscopic evaluation, graph paper projection, image processing, etc., thus sequentially improving accuracy. Two-dimensional porosity is meant to provide a judgment basis regarding the degree of pore development in two-dimensional space so as to quickly evaluate reservoir storage capacity [38][39][40][41][42].…”

Investigation of the Microscopic Pore–Throat Structure Difference of Tight Sandstone/Glutenite Based on a Multifractal Method

“…The current research is mostly focused on the analysis of a specific block but lacks horizontal comparison between tight reservoirs in different blocks and types. − It is crucial to identify the similarities and differences of the pore–throat structure of cores in different blocks. On the one hand, it can provide a reasonable explanation for the close porosity of rocks but significant differences in permeability, and clarify the main controlling factors of flow, which is necessary to consider in permeability evaluation and flow phenomenon interpretation.…”