Search

The proposed method of predicting spatial distribution of leaching zones in carbonate reservoirs includes integrated interpretation of well logging data, including electrical microimages (Formation MicroImager – FMI), together with analysis of lithofacies within depositional cycles. Based on the comparison of FMI data with results of lithological and petrophysical studies of the core, an atlas of diagenetic porosity images for the studied formation was developed. Choquette and Pray international classification was used for pore typing. Applying the developed atlas to FMI logs, karstification zones were identified and classified in reference wells. In wells, where only standard well loggings was performed, karstification zones were identified using a developed decision tree. Sedimentological and sequence stratigraphic analysis made it possible to identify sedimentation cycles and to correlate the main lithofacies within the target reservoir. It was established that microbial and shallow facies form the most productive part of the reservoir. These facies with initially high primary porosity were subjected to the most intensive karstification along sequence stratigraphic boundaries due to subaerial exposure. The established relationships between leaching zones, lithofacies, and sequence-stratigraphic boundaries made it possible to carry out inter-well correlation of karstified intervals. The correlation will allow construction of leaching zones maps, that will be further applied for geological modeling.

Introduction: Cerebral arterial air embolism (CAE) is a serious and potentially dangerous condition that can interrupt the blood supply to the brain and cause stroke. One of the promising gas mixtures for emergency treatment of air embolism is an oxygen-helium mixture.Methods: We modeled CAE in awake rats by injecting air into the common carotid artery. Immediately after CAE, animals were either untreated or underwent hyperbaria, oxygen inhalation, heated air inhalation, or helium-oxygen mixture inhalation. Body temperature, locomotor activity, respiratory and cardiovascular parameters were monitored in the animals before CAE modeling, and 3 and 24 h after CAE modeling.Results: After 3 hours of CAE modeling in awake rats, depression of the nervous, cardiovascular and respiratory systems, as well as decreased body temperature were observed. 24 h after CAE modeling multifocal cerebral ischemia was observed. Normobaric helium-oxygen mixture inhalation, on par with hyperbaric treatment, restored body temperature, locomotor activity, respiratory volume, respiratory rate, and blood pressure 3 hours after CAE, and prevented the formation of ischemic brain damage lesions 24 h after CAE.Discussion: Thus, inhalation of a heated oxygen-helium gas mixture (O2 30% and He 70%) immediately after CAE improves the physiological condition of the animals and prevents the foci of ischemic brain damage formation.