Sequences stratigraphy1/12/2024 ![]() However, only limited studies on the high-frequency sequence and sedimentology have been conducted to study the sequence stratigraphy of shale strata deposited in deep water or restricted shallow water environment. In the past 40 years, the sequence stratigraphic studies mainly focused on the coarse-grained siliciclastic and carbonate deposits and on the fine-grained turbiditic systems from lacustrine to deepwater settings, leading to a great success in the conventional petroleum exploration. Sequence stratigraphy is a relatively new concept of stratigraphy and is a powerful tool to subdivide the stratigraphic intervals into geologically realistic and cyclic patterns and to predict the stratal patterns, the lithofacies variations, and the petroleum reservoirs within a chronostratigraphic unit. Although the success of shale gas exploration in North America leads geologists to believe that shale gas exploration has a good prospect, how to find the sweet spot of shale gas in shale strata is still the main obstacle we need to face in the shale gas exploration and development. They are passionate about finding more commercial shale gas in other countries. The great success of shale gas exploration in North America has attracted increasing attention from petroleum geologists in the world. *Address all correspondence to: Introduction School of Ocean Sciences, China University of Geosciences, China.School of Energy Resources, China University of Geosciences, China.School of Geoscience and Engineering, Southwest Petroleum University, China.Faculty of Earth Resources, China University of Geosciences, China.PetroChina Exploration & Development Research Institute, China. ![]() Key laboratory of strategy evaluation for Shale gas, Ministry of Land and Resources, Beijing, China.Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education (China University of Geosciences), Wuhan, China.Sinopec Key Laboratory of Shale Oil/Gas Exploration and Production Technology, Beijing, China.Energy & Geoscience Institute and Department of Chemical Engineering, UT, USA.Research Institute of Unconventional Oil & Gas and Renewable Energy, China.The best reservoir with the best completion quality is developed in TST and HST in both siliciclastic-dominated and carbonate-dominated fine-grained “shales.” The lithofacies, geochemistry, mineralogy, depositional evolution, and reservoir development have been predicted and correlated within a sequence stratigraphic framework for the suggested cases. TST and EHST of the siliciclastic “shales” are characterized by high gamma ray, high TOC, and high quartz content, while TST and EHST of the carbonate-dominated fine-grained “shales” are characterized by low gamma ray, organic lean, and carbonate rich fine-grained deposits. The case studies for the sequence stratigraphy in the USA and China have revealed that the transgressive systems tract (TST) and the early highstand systems tract (EHST, if identifiable) of fine-grained “shales” have been deposited in anoxic settings. Practical methods are proposed in order to recognize the sequence boundaries, the flooding surfaces, the parasequences and parasequence sets, the system tracts, and variation patterns of facies and rock properties. This chapter examines the variations in lithofacies, patterns of well logs, geochemistry, and mineralogy in order to construct a sequence stratigraphic framework of the representative marine Barnett, Woodford, Marcellus, Mowry, and Niobrara fine-grained “shales” (USA) and the marine Longmaxi shale and lacustrine Chang7 lacustrine shale (China). The fine-grained “shale” deposits host a vast amount of unconventional oil and gas resources.
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |