Application of Light Hydrocarbons in Natural Gas Geochemistry of Gas Fields in China

Light hydrocarbons (LHs) are an important component of natural gas whose chemical and isotopic compositions play a vital role in identifying gas genetic type, thermal maturity, gas–gas correlation, gas–source correlation, migration direction and phase, and secondary alterations (such as evaporative fractionation, biodegradation, and thermochemical sulfate reduction) experienced by the gas pool. Through review of geochemical research into LHs over recent decades, and analysis of chemical and isotopic compositions of LHs of gases and condensates from more than 40 gas fields in China, we present an overview of the genetic mechanisms of LHs and the impacts of various factors on their geochemical compositions. The primary objectives of this review are to demonstrate the application of LH chemical and isotopic composition characteristics to gas geochemistry research and to assess the applicability and reliability of geochemical identification diagrams and parameters for determining gas genetic types, maturity, source, secondary alteration, and migration direction and phase. ▪ Three main genetic mechanisms are proposed for the formation of light hydrocarbons: thermal decomposition, catalytic decomposition of organic matter, and microbial action. ▪ Chemical and isotopic compositions of light hydrocarbons with different carbon numbers and/or structures can be used to identify the genetic types and maturity of natural gas. ▪ Content ratios and carbon isotopes of characteristic light hydrocarbons are good indicators for gas–gas and gas–source correlations. ▪ Secondary alterations (evaporative fractionation, biodegradation, thermochemical sulfate reduction) and migration of gas can be indicated by chemical and isotopic compositions of light hydrocarbons. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Download Full-text

Characteristics and Origins of the Natural Gas and Implications for Gas-Source Correlation in Deep Formations of the Songliao Basin, NE China

Energies ◽

10.3390/en12244641 ◽

2019 ◽

Vol 12 (24) ◽

pp. 4641

Author(s):

Zhengjian Xu ◽

Biao Peng ◽

Yanjun Feng ◽

Luofu Liu ◽

Chao Fang ◽

...

Keyword(s):

Songliao Basin ◽

Source Rocks ◽

Gas Migration ◽

Light Hydrocarbons ◽

Ne China ◽

Gas Source ◽

Genetic Types ◽

Source Correlation ◽

Gas Fields ◽

Oil Cracking

The Songliao Basin is the most productive petroliferous lacustrine basin in NE China, and numerous large gas fields with large proven reserves occur in its deep formations. However, considerable challenges remain: (1) the origins and genetic types of the natural gases are controversial; (2) the gas-source correlations are poorly studied; and (3) the migration distance is vague. In this study, these problems are addressed by the study of the gas compositions, light hydrocarbons, and stable hydrogen and carbon isotopes. The gases are predominantly of organic and thermogenic origins. The Huoshiling (J3h) and Shahezi (K1sh) gases are mainly mixtures of coal-derived and oil-associated gases and the mixed-sources of primary kerogen degradation and secondary oil cracking, while the Yingcheng (K1yc) gases are mainly coal-derived gases and predominantly derived from primary kerogen degradation. The gases in different sags are derived from the source rocks developed in the same sags where the gases accumulated, characterized by the proximal-source accumulation. Vertically, the gases in the J3h and K1sh are predominantly sourced by the proximal J3h and K1sh mudstones, while the gases in the K1yc are mainly derived from either the J3h or the K1sh source rocks, suggesting the gas migration with short distances.

Download Full-text

Sources, trends, and fate of methane in shallow aquifers of Alberta, Canada

10.5194/egusphere-egu2020-10777 ◽

2020 ◽

Author(s):

Pauline Humez ◽

Florian Osselin ◽

Wolfram Kloppmann ◽

Cynthia McClain ◽

Michael Nightingale ◽

...

Keyword(s):

Natural Gas ◽

Sulfate Reduction ◽

Methane Oxidation ◽

Bacterial Sulfate Reduction ◽

Monitoring Wells ◽

Isotopic Compositions ◽

Groundwater Samples ◽

Groundwater Systems ◽

Hydrogeochemical Parameters ◽

Methane Concentrations

Due to concerns regarding potential impacts of the development of natural gas from unconventional hydrocarbon resources on groundwater systems in North America and elsewhere, it has been crucial to improve methods of Environmental Baseline Assessment (EBA). Any subsequent deviations from the EBA could indicate migration of natural gas into the monitored groundwater systems. In collaboration with Alberta Environment and Parks, over 800 groundwater samples have been collected from dedicated monitoring wells since 2006 resulting in an extensive high-quality database of aqueous and gaseous geochemical and isotopic compositions. Because methane is the main component of natural gas, it had been the principal target of our groundwater studies. Our objectives were a) to assess the occurrence of methane in groundwater throughout the province of Alberta (Canada), b) to use isotope techniques to track the predominant sources of methane, c) to use a combination of chemical and multi-isotopic techniques and models to assess the fate of methane in groundwater, and d) to use probability for predicting the presence of methane in groundwater based on hydrogeochemical parameters in regions where no gas data exist.Methane was found to be ubiquitous in groundwater samples throughout the province of Alberta with concentrations varying from 2.9 10-4 to >2.4 mmol/l. The highest methane concentrations were found in Na-HCO3 and Na-Cl water-types where the sulfate concentrations were <1 mmol/l. Analyses of the isotopic compositions of sulfate, dissolved inorganic carbon (DIC) and methane revealed that in some groundwater systems bacterial sulfate reduction occurred (&#948;34SSO4 >+10&#8240; associated with lowest sulfate concentrations) and evidence for methane oxidation was also detected (highest &#948;13CCH4 values > &#8209;55&#8240; associated with lowest methane concentrations). Moreover, some &#948;13CDIC values were as high as +13.8&#8240; associated with the highest methane concentrations. A geochemical and multi-isotope model using long-term monitoring data was developed and revealed two different sources of methane: 1) microbial methane resulting from in-situ methanogenesis within the aquifer for a subset of the samples; 2) migration of microbial methane into aquifers characterized by various redox conditions, followed by methane oxidation potentially coupled with bacterial sulfate reduction within sulfate-rich zones causing a pseudo-thermogenic carbon isotopic fingerprint for the remaining methane. So far, no evidence of unambiguously thermogenic methane in the groundwater samples collected from dedicated monitoring wells has been found. Efforts to assess the probability of regional occurrence of methane in groundwater systems in Alberta have then focused on a model for methane prediction model based on logistic regression (LR) for regions of Alberta where no gas data exist. Using basic hydrogeochemical parameters such as occurrence of electron donors, well depth and total dissolved solids of groundwater, the LR approach shows excellent performance metrics e.g. model sensitivity, specificity >80% regarding the prediction of methane occurrence in groundwater of Alberta.

Download Full-text

Genetic types of natural gas and gas-source correlation in different strata of the Yuanba gas field, Sichuan Basin, SW China

Journal of Asian Earth Sciences ◽

10.1016/j.jseaes.2019.103906 ◽

2019 ◽

Vol 181 ◽

pp. 103906

Author(s):

Xiaoqi Wu ◽

Quanyou Liu ◽

Guangxiang Liu ◽

Chunhua Ni

Keyword(s):

Natural Gas ◽

Sichuan Basin ◽

Gas Field ◽

Sw China ◽

Gas Source ◽

Genetic Types ◽

Source Correlation

Download Full-text

Chemical and isotopic compositions of brines from dissolved-in-water type natural gas fields in Chiba, Japan

GEOCHEMICAL JOURNAL ◽

10.2343/geochemj.40.475 ◽

2006 ◽

Vol 40 (5) ◽

pp. 475-484 ◽

Cited By ~ 14

Author(s):

TATSUO MAEKAWA ◽

SHUN-ICHIRO IGARI ◽

NOBUYUKI KANEKO

Keyword(s):

Natural Gas ◽

Water Type ◽

Isotopic Compositions ◽

Gas Fields

Download Full-text

Geoeconomic Leverage of Natural Gas Resources in the Mediterranean

Contemporary Arab Affairs ◽

10.1525/caa.2019.12.4.141 ◽

2019 ◽

Vol 12 (4) ◽

pp. 141-155 ◽

Cited By ~ 1

Author(s):

Ahmed Mahdi

Keyword(s):

Natural Gas ◽

Economic Resources ◽

Tel Aviv ◽

Economic Influence ◽

The Mediterranean ◽

Influence Attempts ◽

Gas Fields

This article examines the claim that Israel’s natural gas exports from its Mediterranean gas fields will give geopolitical leverage to Tel Aviv over the importing countries. Using the geoeconomic tradition of Klaus Knorr and others who wrote about applying leverage using economic resources to gain geopolitical advantage, it is argued that certain criteria have to be satisfied for economic influence attempts, and that Israel’s gas exports do not satisfy these criteria. They include the importer’s supply vulnerability, the supplier’s demand vulnerability, and the salience of energy as an issue between both countries. Israeli gas exports to Egypt are used as a case study.

Download Full-text

Prospects of Using Hydrocarbon Deposits from the Autochthonous Miocene Formation (Eastern Carpathian Foredeep, Poland) for Geothermal Purposes

Energies ◽

10.3390/en14113102 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3102

Author(s):

Anna Chmielowska ◽

Anna Sowiżdżał ◽

Barbara Tomaszewska

Keyword(s):

Oil And Gas ◽

Geothermal System ◽

Vast Number ◽

Hydrocarbon Traps ◽

Oil And Gas Fields ◽

Geothermal Potential ◽

Carpathian Foredeep ◽

And Migration ◽

Gas Fields ◽

Geothermal Parameters

There are many oil and gas fields around the world where the vast number of wells have been abandoned or suspended, mainly due to the depletion of reserves. Those abandoned oil and gas wells (AOGWs) are often located in areas with a prospective geothermal potential and might be retrofitted to a geothermal system without high-cost drilling. In Poland, there are thousands of wells, either operating, abandoned or negative, that might be used for different geothermal applications. Thus, the aim of this paper is not only to review geothermal and petroleum facts about the Eastern Carpathian Foredeep, but also to find out the areas, geological structures or just AOGWs, which are the most prospective in case of geothermal utilization. Due to the inseparability of geological settings with both oil and gas, as well as geothermal conditionings, firstly, the geological background of the analyzed region was performed, considering mainly the autochthonous Miocene formation. Then, geothermal and petroleum detailed characteristics were made. In the case of geothermal parameters, such as formation’s thickness, temperatures, water-bearing horizons, wells’ capacities, mineralization and others were extensively examined. Considering oil and gas settings, insights into reservoir rocks, hydrocarbon traps and migration paths issues were created. Then, for evaluating geothermal parameters for specific hydrocarbon reservoirs, their depths were established based on publicly available wells data. Thereafter, the average temperatures for selected reservoirs were set. As the effect, it turned out that most of the deposits have average temperatures of 40/50 °C, nonetheless, there are a few characterized by higher (even around 80 °C) temperatures at reasonable depths.

Download Full-text