The identification and prediction of petrofacies plays a crucial role in the study of shale oil and gas “sweet spots”. However, the petrofacies identified through core and core test data are not available for all wells. Therefore, it is essential to establish a petrofacies identification model using conventional well logging data. In this study, we determined the petrofacies of shale oil reservoirs in the Upper Triassic Yanchang Formation, Ordos Basin, China, based on scanning electron microscopy, core porosity and total organic carbon (TOC), and brittleness index calculations from X-ray diffraction (XRD) experiments conducted on seven members of the formation. Furthermore, we compared the interpreted logs with the raw well logs data clustered into electrofacies in order to assess their compliance with the petrofacies, using the Multi-Resolution Graph-Based Clustering (MRGC) method. Through an analysis of pore structure type, core porosity, TOC, and brittleness index, we identified four types of lithofacies with varying reservoir quality: PF A > PF B > PF C > PF D. The compliance of the clustered electrofacies with the petrofacies obtained from the interpreted logs was found to be 85.42%. However, the compliance between the clustered electrofacies and the petrofacies obtained from the raw well logs was only 47.92%. Hence, the interpreted logs exhibit a stronger correlation with petrofacies characterization, and their utilization as input data is more beneficial in accurately predicting petrofacies through machine learning algorithms.
To alleviate soil deterioration caused by tobacco continuous cropping obstacles, the effect of reductive soil disinfestation (RSD) on soil physicochemical and biological characteristics as well as tobacco growth was investigated through a pot experiment, with four treatments including control (CK), moderate nitrogen fertilizer application (NF), RSD, and RSD coupled with NF (RF). Results showed that soil pH, the content of organic matter, available P and available Fe were significantly increased after using RSD technology. Moreover, RSD technology boosted the relative abundance of Gemmatimonadota (9.0–12.0%), Chloroflexi (4.0–11.0%), and Ascomycota (10.0–12.0%) while decreasing the relative abundance of Mucoromycota (2–4%). Therefore, the biomass and quality of tobacco were also improved after the RSD application. Compared with CK, the biomass of tobacco at the mature stage was increased by 233.7–262.8% by RSD technology, and the chemical coordination (sugar difference, sugar alkali ratio and alkali nitrogen ratio) of the plant was also significantly improved. This study verified the feasibility of RSD technology in repairing soil deterioration caused by tobacco continuous cropping obstacles and provided theoretical and technical support for long-term tobacco production.
Abstract Fluid type identification in the carbonate reservoirs is always a challenge work due to the heterogeneous composition. The normal resistivity well logging data cannot separate gas and water formation for such complex reservoirs has been reported in the former studies. Moreover, the traditional cross-plot also cannot find the low limit value. Thus in this paper, we proposed the new statistics evaluation methods to solve such problems based on multi-parameters identified method which chose 10 parameters as dataset and utilized decision tree to build the rules, and discriminant analysis which build 2 predictive models (A and B) to classify the gas and water. We indeed successfully applied our new methods on the true well logging data from a heterogeneous carbonate reservoir in China. Thus we concluded that our new methods could be a good way in the future well logging evaluation for complex carbonate reservoir.
CO2 injection into carbonate reservoirs for CO2 enhanced oil recovery (EOR) and carbon dioxide geosequestration is a key technique to enhanced oil / gas production and mitigate anthropogenic greenhouse gas emissions. However, the carbonate rock is chemically sensitive as reacts when exposed to the acidic fluid (which is created by the CO2-saturated brine), results the formation dissolved. And such reactive transport processes are only poorly understood, particularly at the 3D micrometre scale. We thus used the novel microCT in-situ core flooding system and imaged a heterogeneous Savonnières limestone core sample before and after flooding with dead brine and CO2- saturated brine at representative reservoir condition (323 K / 50°C temperature, 15 MPa confining pressure, 10 MPa pore pressure) in-situ at high resolutions (3.43 µm and 1.25 μm voxel size) in 3D. After the imaging processing such as filter and segmentation, we indeed observed the carbonate rock matrix partially dissolved, consistent with the total porosity, effective porosity and permeability significantly increased. We also find such dissolution was confined to the original flow channels and inlet points.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
'/%3e%3c/defs%3e%3cpath fill='%23012169' d='M0 0h10080v5040H0z'/%3e%3cpath stroke='%23fff' stroke-width='.6' d='m0 0 6 3m0-3L0 3' clip-path='url(%23b)' transform='scale(840)'/%3e%3cpath stroke='%23e4002b' stroke-width='.4' d='m0 0 6 3m0-3L0 3' clip-path='url(%23c)' transform='scale(840)'/%3e%3cpath stroke='%23fff' stroke-width='840' d='M2520 0v2520M0 1260h5040'/%3e%3cpath stroke='%23e4002b' stroke-width='504' d='M2520 0v2520M0 1260h5040'/%3e%3cg fill='%23fff'%3e%3cuse xlink:href='%23d' x='2520' y='3780'/%3e%3cuse xlink:href='%23a' x='7560' y='4200'/%3e%3cuse xlink:href='%23a' x='6300' y='2205'/%3e%3cuse xlink:href='%23a' x='7560' y='840'/%3e%3cuse xlink:href='%23a' x='8680' y='1869'/%3e%3cuse xlink:href='%23e' x='8064' y='2730'/%3e%3c/g%3e%3c/svg%3e)