Important Achievement and Advance of Natural Gas Geology and Geochemical Exploration in China

Academician Dai Jinxing has long been engaged in natural gas geology and geochemical researches,and has made prominent contributions to the establishment and development of China’s theory of coal-derived gas.He has opened up new areas of coal-derived gas exploration,natural gas formation theory and formation“ control conditions of large ” medium gas fields.

Research Progress in the Petroleum and Natural Gas Geological Theory of China

The Chinese landmass, as a composite region, consists of multiple small continental blocks, such as Sino-Korea, Yangtze, Tarim, etc., and orogenic belts. Because of its distinctive tectono-sedimentary evolution, China＇s oil/gas-bearing regions differ remarkably from that elsewhere in the world. For instance, in comparison to the Middle East oil/gas-bearing regions which are characterized by Mesozoic-Cenozoic marine oil/gas-bearing beds, early oil and gas discoveries in China are distributed mainly in Mesozoic-Cenozoic continental sedimentary basins. Generation of oil from terrestrial organic matter, or terrestrial oil generation, and the formation of large oil/gas fields in continental sedimentary basins were previously the major characteristics of petroleum geology of China. However, in the past 20 years, a series of major oil and gas discoveries from marine strata have been made. Marine oil/gas fields in China are mainly distributed in the Tarim, Sichuan, and Ordos basins, which are tectonically stable and covered with Mesozoic-Cenozoic deposits. In these basins, hydrocarbon-bearing strata are of old age and the oil/gas fields are commonly deeply-buried. Cumulatively, 995 oil/gas fields have been found so far, making China the fourth largest oil-producing country and the sixth largest gas-producing country in the world. In terms of petroleum and natural gas geology, theories of hydrocarbon generation from continental strata, such as terrestrial oil generation and coal-generated hydrocarbons, etc., have been established. Significant progress has been made in research on the sequence stratigraphy of continental strata, formation mechanisms of ultra-deep clastic reservoirs, and hydrocarbon accumulation in the continental subtle reservoir. Regarding research on the marine petroleum geology of China, with respect to the major characteristics, such as deeply-buried reservoirs, old strata, and multiple phases of transformation, important advances have been made, in areas such as the multiple-elements of hydrocarbon supply, formation of reservoirs jointly controlled by deposition, tectonic activities, and diagenetic fluid-rock reactions, and oil/gas reservoirs formed through superimposed multi-stage hydrocarbon accumulation. As more and more unconventional hydrocarbon resources are discovered, unconventional oil and gas reservoirs are under study by Chinese petroleum geologists, who endeavor to come up with new discoveries on their formation mechanisms.

Effect of natural prolongation with geological features on maritime delimitation

The United Nations Convention on the Law of the Sea entitled the coastal States to naturally extend the continental shelf, which has caused more drastic disputes of maritime delimitation. This paper devotes to clarifying the significant concept of natural prolongation through an effect method combing the legal principles and technical analysis. Firstly, the classic samples with respect of the development of geological features are traced. Based on these samples, the classification with a model is proposed in order to affirm the concept＇s significance under certain geomorphologic situations. Lastly, scientific analysis is used to present two potential prolongation situations and emphasize that all the technical analysis on maritime delimitation should be complied with international law and protect the common interest of all the mankind.

The Genetic Mechanism and Model of Deep-Basin Gas Accumulation and Methods for Predicting the Favorable Areas

As a kind of abnormal natural gas formed with special mechanism, the deep-basin gas, accumulated in the lower parts of a basin or syncline and trapped by a tight reservoir, has such characteristics as gas-water inversion, abnormal pressure, continuous distribution and tremendous reserves. Being a geological product of the evolution of petroliferous basins by the end of the middle-late stages, the formation of a deep-basin gas accumulation must meet four conditions, i.e., continuous and sufficient gas supply, tight reservoirs in continuous distribution, good sealing caps and stable structures. The areas, where the expansion force of natural gas is smaller than the sum of the capillary force and the hydrostatic pressure within tight reservoirs, are favorable for forming deep-basin gas pools. The range delineated by the above two forces corresponds to that of the deep-basin gas trap. Within the scope of the deep-basin gas trap, the balance relationship between the amounts of ingoing and overflowing gases determines the gas-bearing area of the deep-basin gas pool. The gas volume in regions with high porosity and high permeability is worth exploring under current technical conditions and it is equivalent to the practical resources (about 10%-20% of the deep-basin gas). Based on studies of deep-basin gas formation conditions, the theory of force balance and the equation of material balance, the favorable areas and gas-containing ranges, as well as possible gas-rich regions are preliminarily predicted in the deep-basin gas pools in the Upper Paleozoic He-8 segment of the Ordos basin.

The paleoclimate environment and recent sea level change on the seashores of Thailand Gulf in Southeast Asia

This paper analyzed and researched on several significant natural geological sections from the views of stratum-sequence stratigraphy,climate stratigraphy,event stratigraphy and regional stratigraphy by the investigation of Thailand,Malaysia and Singapore. In combination with the coupling relationship between the life-temperature of regional life zone and the evolution of geological environment,this paper exactly made out the geological sediment records of paleoclimate times in different time scales of 3 kaBP,1 kaBP and 0.5 kaBP since the past glacier age of Quaternary period,and it is consecutive and authentic for the material medium and time joint. These studies definitely reflected that the sea level of Thailand Gulf area is in tendency of continually dropping in recent years. They also provided important and new information for the global change analysis.

Integrating NLP and Ontology Matching into a Unified System for Automated Information Extraction from Geological Hazard Reports

Many detailed data on past geological hazard events are buried in geological hazard reports and have not been fully utilized. The growing developments in geographic information retrieval and temporal information retrieval offer opportunities to analyse this wealth of data to mine the spatiotemporal evolution of geological disaster occurrence and enhance risk decision making. This study presents a combined NLP and ontology matching information extraction framework for automatically recognizing semantic and spatiotemporal information from geological hazard reports. This framework mainly extracts unstructured information from geological disaster reports through named entity recognition, ontology matching and gazetteer matching to identify and annotate elements, thus enabling users to quickly obtain key information and understand the general content of disaster reports. In addition, we present the final results obtained from the experiments through a reasonable visualization and analyse the visual results. The extraction and retrieval of semantic information related to the dynamics of geohazard events are performed from both natural and human perspectives to provide information on the progress of events.