Natural Gas Industry 

About: Natural Gas Industry is an academic journal. The journal publishes majorly in the area(s): Natural gas & Natural gas field. It has an ISSN identifier of 1000-0976. Over the lifetime, 773 publications have been published receiving 2601 citations.

Geological condition of shale gas accumulation in sichuan basin

Abstract: Distinguished by what from traditional conception of fissured shale gas, shale gas is concerned to the gas accumulated within the shales and/or mudstones by free and adsorbed gas. The Sichuan Basin experienced complex tectonic movements in process of the evolution from Craton basin to foreland basin. As a result, The Sichuan Basin is of the similar tectonic characteristics and geological conditions for shale gas with the typical shale gas basins in America, where the Paleozoic shale is not only the source rocks for conventional gas reservoirs but also the main objects for shale gas accumulation and exploration. At present, a large number of evidences of shale gas have been found in the Sichuan Basin. According to the structural and evolutional characteristics of the Sichuan Basin, the unconventional gas is distributed by two distinguished patterns: in place, shale gas is mainly in the southeastern basin while the source-contacting gas in the northwestern basin; in time, shale gas accumulated in the Paleozoic Erathem while source-contacting gas in the Mesozoic Erathem. In North and South Sichuan Basin, including Southwestern Sichuan Basin, there developed Paleozoic Erathem gas bearing shales with huge thickness, high contents of organic matters and shallow buried depths. Lower Cambrian and Lower Silurian Series are of good geological conditions for shale gas accumulation and exploration. In Central Sichuan Basin there developed both Mesozoic and Paleozoic Erathems of source rocks, in which Upper Triassic Series is the favorable horizon for shale gas exploration. In West Sichuan Basin the gas bearing shales is mainly Mesozoic Erathem, in which shales and tight sands interbed frequently to form the source-contacting gas with the characteristics of gas accumulated on the bottom of tight sands. There exist perspective conditions for exploration and exploitation of shale gas in West Sichuan Basin, especially the high carbon shales and/or mudstones with relatively shallower depths.

Exploration potential of shale gas resources in china

Abstract: Shale gas is a kind of unconventional natural gas which mainly exists as adsorbed and free gas in shalesShale gas or gas shale is extensively variable on the genetic mechanism,existing phase,accumulation mechanism,distribution variation,and relationship with other kinds of gas reservoirsSince the boundary conditions for shale gas accumulation can be broadened moderately and the variation can be very extensive,every geological element for gas accumulation in shales is of obvious complementarity with each otherBased on geology analysis,logging data and seismic study,shale gas accumulations can be rapidly recognizedIt demonstrates that there exist favorable geological conditions for regional distribution of shale gas in China,of which the primarily assessed resources of shale gas is about 15-30 tcmThe most profitable regions are South and Northwest China,including the Ordos basin and vicinage basinsAmong the regions,the resource of shale gas in Paleozoic is the largest,while the second is in Mesozoic

Accumulation types and resources characteristics of shale gas in China

Abstract: Through comparison analysis of shale gas accumulation conditions and the similarity of geological conditions in the U.S.A and China,this study concluded that both countries have similar geological conditions favorable for shale gas accumulation and have approximate shale gas resource reserves and development potentials.In general,the gas-bearing shale layers in China possess high TOC,high thermal maturity and a high degree of later reformation.Shale gas accumulations are characterized by terrestrial facies deposit,controlled by sedimentation region division,and various and complicated distribution.Shale gas accumulations can be classified into direct and indirect types,and also can be divided into three types as southern type,northern type and north-western type according to the regional geologic conditions in China.The southern type of shale gas,distributed around the Yangtze plate,is mostly accumulated in the Paleozoic marine shale which experienced intensive structural reformation,and is featured by a large thickness of a single layer,multiple developed layers,a wide distribution area,high thermal maturity,and a high degree of later reformation,etc.The northern type of shale gas,distributed in the north China plate,is mostly accumulated in the groups from Paleozoic via Mesozoic to Neozoic,and is characterized by sedimentary migration,a high frequency of thin interbedded layers,and an obvious division between sedimental facies.The north-western type of shale gas,distributed around the Tarim Plate,is accumulated in the groups from Paleozoic to Mesozoic,and has the characteristics of various types of sedimentation,high TOC,and relatively low thermal maturity.It is concluded that the recoverable shale gas resources is predicated to be about 26 tcm in China,close to 28 tcm of that in the U.S.A.

Preliminary discussion on natural gas hydrate (ngh) reservoir system of shenhu area,north slope of south china sea

Abstract: The reservoir system for natural gas hydrate (NGH) is very complicated and unfortunately there were not so many studies on this issue in the past years. Therefore, this study took as a case of study the samples which were first obtained by NGH drilling in the northern slope of South China Sea. According to essential factors for forming NGH reservoirs, the NGH source and distribution features reflected by intergranular water geochemical characteristics of shallow sediments, this study discussed preliminarily on the NGH reservoir system in the Shenhu area, the northern slope of South China Sea. The study showed some results as follows: (1) In the study area, temperature, pressure, and gas compositions were all favorable for the formation of NGH; (2) The high-resolution seismic data and the gas hydrate drilling getting high concentrations of hydrate (40%) in a disseminated forms in foram-rich clay sediments showed that gas hydrate was distributed heterogeneously at all spatial scales in the study area, and the hydrate-bearing sediments ranged several ten meters in thickness were located in the lower part of gas hydrate stability zone (GHSZ), just above the bottom of gas hydrate stability zone (BGHSZ); (3) The NGH gas originated at all probability from in-situ microbiogenic methane; (4) In-situ microbial methane production resulted in a low vertical methane flux and generated a distributed NGH reservoir system with distinctive patterns of distribution and concentration within the very fine sediments.

Accumulation conditions of shale gas reservoirs in Silurian of the Upper Yangtze region

Abstract: Silurian which is widely distributed in Upper Yangtze area in South China develops a set of excellent hydrocarbon source rocks deposited in the anoxic environment with still water,especially the Lower Silurian Longmaxi formation in the Sichuan basin in which black graptolite shale is most developed.Judged from the organic geochemical parameters of this formation and testing data of new drilled shallow shale gas wells in Changning structure in southern Sichuan basin,Silurian Longmaxi formation is characterized by high abundance of organic matter,higher maturity,rich microfracture and moderate buried depth,thus possessing favorable conditions to form shale gas reservoirs.The organic carbon content of shale with average thickness ranging from 40-80 m is more than 2% in such areas as Shizhu in East Sichuan,Lichuan in West Hubei,Luzhou in South Sichuan and Zhenba in North Sichuan while the maturity criteria of shale is mostly less than 3% in regions such as Luzhou-Yibing-Zigong,Majiang-Weng'an in middle Guizhou,Xiushan-Songtao in South Sichuan and Jishou in West Hunan.There encounters gas logging abnormality,gas cut and well kicks when drilled Silurian shale formation in such exploratory wells as Yangshen-2,Yang-63,Yang-9,Fushen-1,Long-32 and Tai-15 etc.The existence of Silurian shallow shale gas is also proved by Changxin-1 well in which the average volume of shale gas is 0.15 m3/t.There is good microfracture growth and high content of quartz and calcite in this set of shale characterized by brittleness.It is estimated preliminarily by the volume method that the Silurian Longmaxi formation has(4.0-12.4)×1012 m3 of shale gas in the Sichuan basin and its neighboring area,showing an enormous potential in exploring shale gas in this area.