The facies-genetic type of triassic sediments and the main oil and gas formations of the Mangyshlak peninsula

Abstract

This paper presents the results of many years of research by the authors. The facies-genetic types of Triassic deposits of the Mangyshlak region have been studied in detail.It is shown that the Triassic and especially the Middle and Upper Jurassic sediments are enriched with more dispersed organic matter than in comparison with the layers below and above. According to the analysis results, the Jurassic and Lower Cretaceous sediments are characterized by abnormal values of dispersed bituminous matter compared to other rocks.The bitumen content is generally low (from 0.01 to 0.5%). Jurassic deposits are characterized by higher values than Lower Cretaceous ones. At the same time, a detailed study of the distribution of organic residues (including faunal remains) gives grounds to classify the entire Triassic-Jurassic-Lower Cretaceous regional oil and gas complex (with the exception of the lower part of the Neocomian and Triassic) as shallow-marine sediments of stable and moderate sedimentation regimes. Oil and gas formations, regional patterns of their distribution in the sedimentary cover of the Mangyshlak region, as well as the adjacent oil and gas region, have been studied in detail. The main oil and gas bearing formations of the Mangyshlak region include the pre-Permian substrate (Devonian, carboniferous), Permian terrigenous-clay and carbonate-chemogenic formation (transitional) (Permian), terrigenous-clay colorful-gray-dark gray-colored (subglenic) (Triassic, Lower Middle Jurassic, Kellovian), carbonate-chemogenic-the clay formation (Oxford-Kimmeridge), the sandy-carbonate-clay formation (Neocom) and the clay-sand formation (apt-Alba) also distinguish them in the northern and southern regions with their common rocks, the nature of development and the degree of research. Over the next thirty years, associated with the cessation of regular parametric, exploratory drilling, and various seismic operations.Despite the large volume of scientific, technical and other research, studies of promising deposits and territories are conducted extremely poorly.One of the important reasons for this is the interdepartmental, intersectoral variance of the work performed, the low variance of the information received. In order to increase the efficiency of the exploration and research complex of productive formations, in our opinion, the solution of the issue of oil and gas exploration and exploration in the Mesozoic of the Mangyshlak region should be carried out according to a single intersectoral, interdepartmental program with an assessment of the progress of work on further stages and final results.