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Gas Field (gas + field)

Distribution by Scientific Domains

Earth and Environmental Science	80%
Business, Economics, Finance and Accounting	20%

Selected Abstracts

Diagenesis and Their Succession of Gas-bearing and Non-gas-bearing Reservoirs in the Sulige Gas Field of Ordos Basin, China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 6 2009
ZHU Xiaomin
Abstract: Comparisons have been made among lithology, diagenesis, and reservoir characteristics of gas-bearing and non-gas-bearing ones in the Sulige gas field of the Ordos Basin based on the laboratory analysis of thin sections, scanning electron microscope, and liquid inclusion of the reservoirs. The reservoirs of the Sulige gas field are now in the middle stage of diagenesis and have undergone compaction, cementation and dissolution. The secondary pore of the reservoir originated from the dissolution of the feldspar and tuff because of the organic acid action from the source rocks during the diagenetic middle stage. Gas-bearing reservoirs are common in soluble pore diagenetic facies of coarse detritus quartzose sandstone, whereas non-gas-bearing ones are common in tense compaction diagenetic facies of mud-bearing medium-fine detritus quartzose sandstone and residual intergranular pore diagenetic facies of mud-bearing medium-coarse detritus quartzose sandstone. The secondary pore is developed in gas-bearing reservoirs of the Sulige gas-field as the medium-coarse grain reservoirs formed in a powerful sedimentary environment and experienced strong dissolution. However, the sediments of fine grain size form the non-gas-bearing reservoirs because of less residual primary pore and secondary pore. [source]

Basic Types and Structural Characteristics of Uplifts: An Overview of Sedimentary Basins in China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 2 2009
Dengfa HE
Abstract: The uplift is a positive structural unit of the crust It is an important window for continental dynamics owing to its abundant structural phenomena, such as fault, fold, unconformity and denudation of strata. Meanwhile, it is the very place to store important minerals like oil, natural gas, coal and uranium. Giant and large-scale oil and gas fields in China, such as the Daqing Oilfield, Lunnan-Tahe Oilfield, Penglai 19,3 Oilfield, Puguang Gas Field and Jingbian Gas Field, are developed mainly on uplifts. Therefore, it is the main target both for oil and gas exploration and for geological study. The uplift can be either a basement uplift, or one developed only in the sedimentary cover. Extension, compression and wrench or their combined forces may give rise to uplifts. The development process of uplifting, such as formation, development, dwindling and destruction, can be taken as the uplifting cycle. The uplifts on the giant Precambrian cratons are large in scale with less extensive structural deformation. The uplifts on the medium- and small-sized cratons or neo-cratons are formed in various shapes with strong structural deformation and complicated geological structure. Owing to changes in the geodynamic environment, uplift experiences a multi-stage or multi-cycle development process. Its geological structure is characterized in superposition of multi-structural layers. Based on the basement properties, mechanical stratigraphy and development sequence, uplifts can be divided into three basic types , the succession, superposition and destruction ones. The succession type is subdivided into the maintaining type and the lasting type. The superposition type can be subdivided into the composite anticlinal type, the buried-hill draped type, the faulted uplift type and the migration type according to the different scales and superimposed styles of uplifts in different cycles. The destruction type is subdivided into the tilting type and the negative inverted type. The development history of uplifts and their controlling effects on sedimentation and fluids are quite different from one another, although the uplifts with different structural types store important minerals. Uplifts and their slopes are the main areas for oil and gas accumulation. They usually become the composite oil and gas accumulation zones (belts) with multiple productive formations and various types of oil and gas reservoirs. [source]

Accumulation Mechanisms and Evolution History of the Giant Puguang Gas Field, Sichuan Basin, China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2009
Fang HAO
Abstract: Solid bitumens were found throughout the carbonate reservoirs in the Puguang gas field, the largest gas field so far found in marine carbonates in China, confirming that the Puguang gas field evolved from a paleo-oil reservoir. The fluid conduit system at the time of intensive oil accumulation in the field was reconstructed, and petroleum migration pathways were modeled using a 3-D model and traced by geochemical parameters. The forward modeling and inversion tracing coincided with each other and both indicated that oils accumulated in the Puguang-Dongyuezhai structure originated from a generative kitchen to the northwest of the Puguang gas field. The deposition of organic-rich Upper Permian source rocks dominated by sapropelic organic matter in the Northeast Sichuan Basin, the development of fluid conduit system that was vertically near-source rock and laterally near-generative kitchen, and the focusing of oils originated from a large area of the generative kitchen, were the three requirements for the formation of the giant paleo-oil reservoir from which the giant Puguang gas field evolved. The Puguang gas field had experienced a three-stage evolution. The post-accumulation processes, especially the organic-inorganic interaction in the hydrocarbon-water-rock system, had not only profoundly altered the composition and characteristics of the petroleum fluids, but also obviously changed the physicochemical conditions in the reservoir and resulted in complicated precipitation and solution of carbonate minerals. [source]

The creation of an asymmetric hydraulic fracture as a result of driving stress gradients

GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2009
T. Fischer
SUMMARY Hydraulic fracture stimulation is frequently performed in hydrocarbon reservoirs and geothermal systems to increase the permeability of the rock formation. These hydraulic fractures are often mapped by hypocentres of induced microearthquakes. In some cases microseismicity exhibits asymmetry relative to the injection well, which can be interpreted by unequal conditions for fracture growth at opposite sides of the well or by observation effects. Here we investigate the role of the lateral change of the minimum compressive stress. We use a simple model to describe the relation among the lateral stress gradient, the mean viscous pressure gradients in the fracture wings, the fracture geometry, and the net pressure in the fracture. Our model predicts a faster fracture growth in the direction of decreasing stress and a limited growth in the opposite direction. We derive a simple relationship to estimate the lateral stress gradient from the injection pressure and the shape of the seismic hypocentre cloud. The model is tested by microseismic data obtained during stimulation of a Canyon Sands gas field in West Texas. Using a maximum likelihood method we fit the parameters of the asymmetric fracture model to the space,time pattern of hypocentres. The estimated stress gradients per metre are in the range from 0.008 to 0.010 times the bottom-hole injection overpressure (8,10 kPa m,1 assuming the net pressure of 1 MPa). Such large horizontal gradients in the order of the hydrostatic gradient could be caused by the inhomogeneous extraction of gas resulting in a lateral change of the effective normal stress acting normal to the fracture wall. [source]

Real Options Analysis: Where Are the Emperor's Clothes?

JOURNAL OF APPLIED CORPORATE FINANCE, Issue 2 2005
Adam Borison
Once a topic of interest only to finance specialists, real options analysis now receives active, mainstream attention in business schools and industry. This article provides practitioners with a critical review of five well-established real options approaches that are extensively documented in the academic and professional literature. These approaches include the "classic approach" and "revised classic approach" (as proposed by Martha Amram and Nalin Kulatilaka), the "subjective approach" (as proposed by Tim Luehrman), the "MAD Approach" (as proposed by Tom Copeland and Vladimir Antikarov), and the "integrated approach" (as proposed by James Smith and Robert Nau). The article discusses the assumptions, mechanics, and potential range of applications of each approach, along with the results when applied to a simple case involving development of a natural gas field. While the approaches share a focus on investment flexibility and shareholder value, they rely on fundamentally different assumptions, use significantly different techniques, and can produce dramatically different results. Consequently, a great deal of thought must go into selecting and applying them in practice. The revised classic approach appears to be best suited to cases dominated either by "market" risk or "private" risk alone, and where approximate results are acceptable and resources are limited. The integrated approach is best suited to cases with a mix of market and technological risks, and where accuracy and a management roadmap are critical. [source]

THE WESTERN AUSTRALIAN POWER DILEMMA,

AUSTRALIAN ECONOMIC PAPERS, Issue 4 2009
PAUL SIMSHAUSER
From 1984 gas-fired power generation had been gradually increasing its share of the electricity market in Western Australia (WA) starting at 1 per cent and rising to about 50 per cent by 2008. Had it continued on this trajectory, the WA power system would have made great advances in terms of cost and environmental efficiencies given the looming commencement of the Carbon Pollution Reduction Scheme in Australia from 2011. However, more recently the cost of natural gas has increased from $3/GJ to $7/GJ following the sudden collapse of the East Spar gas field in the North West Shelf. In this article, we analyse the impact of the gas price increase and demonstrate that despite being the most environmentally efficient conventional technology, natural gas combined cycle plant has been squeezed out of the market which in turn will increase forward electricity price risks to WA consumers through greater exposure to CO2 pricing in the long run. [source]

Alkyl Naphthalenes and Phenanthrenes: Molecular Markers for Tracing Filling Pathways of Light Oil and Condensate Reservoirs

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 5 2010
LI Meijun
Abstract: Condensates and light oils are generally characterized by high maturity, low concentration of sterane and terpane biomarkers and low content of non-hydrocarbon fraction. As a result, some commonly-used sterane, terpane and carbazole migration parameters in conventional oil reservoirs may have a certain limitation in condensate and light oil reservoirs for their poor signal-noise ratios in the gas chromatography-mass spectrometry (GC-MS). Naphthalene, phenanthrene and their methylated substituents, however, are present in significant concentrations in condensates and light oils. Taking the Fushan depression (in the Beibuwan Basin, Northern South China Sea) as an example, this paper attempts for the first time to use polycyclic aromatic hydrocarbon (PAH)-related parameters to trace migration directions and filling pathways for condensate and light oil reservoirs. The result shows that TMNr (i.e. 1,3,7-TMN/ (1,3,7-TMN + 1,2,5-TMN), TMN: trimethylnaphthalene)), MPI-1 (i.e. 1.5×(2-MP + 3-MP)/(P + 1-MP + 9-MP), P: phenanthrene MP: methylphenanthrene), MN/DMN (,methylnaphthalene/,dimethylnaphthalene, %) and MN/TMN (,methylnaphthalene/,trimethylnaphthalene, %) can be used to trace the filling pathways of condensate and light oil reservoirs. These parameters, together with geological consideration and other bulk oil properties (e.g. the gas to oil ratio and density), suggest that the condensates and light oils in the Huachang oil and gas field are mainly sourced from the Bailian sag that is located to the northeast of the Huachang uplift in the Fushan depression. [source]

Diagenesis and Their Succession of Gas-bearing and Non-gas-bearing Reservoirs in the Sulige Gas Field of Ordos Basin, China

Structural Evolution of the Eastern Qiulitagh Fold and Thrust Belt, Northern Tarim Basin, China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 2 2009
Minghui YANG
Abstract: The eastern Qiulitagh fold and thrust belt (EQFTB) is part of the active Kuqa fold and thrust belts of the northern Tarim Basin. Seismic reflection profiles have been integrated with surface geologic and drill data to examine the deformation and structure style of the EQFTB, particularly the deformational history of the Dina 2 gas field. Seismic interpretations suggest that Dongqiu 8 is overall a duplex structure developed beneath a passive roof thrust, which generated from a tipline in the Miocene Jidike Formation, and the sole thrust was initiated from the same Jidike Formation evaporite zone that extends westward beneath the Kuqatawu anticline. Dongqiu 5 is a pop-up structure at the western part of the EQFTB, also developed beneath the Jidike Formation evaporite. Very gentle basement dip and steep dipping topographic slope in the EQFTB suggest that the Jidike Formation salt provides effective decoupling. The strong deformation in the EQFTB appears to have developed further south, in an area where evaporite may be lacking. Since the Pliocene, the EQFTB has moved farther south over the evaporite and reached the Yaken area. Restoring a balanced cross-section suggests that the minimum shortening across the EQFTB is more than 7800 m. Assuming that this shortening occurred during the 5.3 Ma timespan, the shortening rate is approximately 1.47 mm/year. [source]

Accumulation Mechanisms and Evolution History of the Giant Puguang Gas Field, Sichuan Basin, China

Source Rocks for the Giant Puguang Gas Field Sichuan Basin: Implication for Petroleum Exploration in Marine Sequences in South China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2008
ZOU Huayao
Abstract: Detailed geochemistry studies were conducted to investigate the origin of solid bitumens and hydrocarbon gases in the giant Puguang gas field. Two types of solid bitumens were recognized: low sulfur content, low reflectance (LSLR) solid bitumens in sandstone reservoirs in the Xujiahe Formation and high sulfur content, high reflectance (HSHR) solid bitumens in the carbonate reservoirs in the Lower Triassic Feixianguan and Upper Permian Changxing formations. Solid bitumens in the Upper Triassic Xujiahe Formation correlate well with extracts from the Upper Triassic to Jurassic nonmarine source rocks in isotopic composition of the saturated and aromatic fractions and biomarker distribution. Solid bitumens in the Feixianguan and Changxing formations are distinctly different from extracts from the Cambrian and Silurian rocks but display reasonable correlation with extracts from the Upper Permian source rocks both in isotopic composition of the saturated and aromatic fractions and in biomarker distribution, suggesting that the Permian especially the Upper Permian Longtan Formation was the main source of solid bitumens in the carbonate reservoirs in the Feixianguan and Changxing formations in the Puguang gas field. Chemical and isotopic composition of natural gases indicates that the majority of hydrocarbon gases originated from sapropelic organic matter and was the products of thermal cracking of accumulated oils. This study indicates that source rock dominated by sapropelic organic matter existed in the Upper Permian and had made major contribution to the giant Puguang gas field, which has important implication for petroleum exploration in marine sequences in South China. [source]

Exploration and development of Iran's oilfields through buyback

NATURAL RESOURCES FORUM, Issue 3 2006
Abdolhossein Shiravi
Abstract The use of buyback for the development of oil and gas fields is an established mechanism in Iran. Current legislation authorizes the National Iranian Oil Company (NIOC) to use buyback for both exploration and development. The buyback scheme can be defined as a risk service contract, under which the contractor is paid back by being allocated a portion of oil/gas produced as a result of providing services. Buyback is based upon a defined scope of work, a capital cost ceiling, a fixed remuneration fee and a defined cost recovery period. When buyback is used for both exploration and development, the specifications of the field to be developed are unknown at the time of contracting and therefore agreement on the scope of work, duration of development operations, ceiling for capital costs, fixed remuneration fee, and duration of cost recovery need to be deferred to the time when a commercial field is discovered. This article first outlines the introduction of buyback for development of Iran's oil and gas fields. It then examines the main features of the mechanism. Third, the use of buyback for both exploration and development is explored and related challenges discussed. Finally, the article reviews the new buyback model proposed by NIOC to address these challenges. [source]

Indonesia fights off oil and gas crises

OIL AND ENERGY TRENDS, Issue 4 2005
Article first published online: 12 APR 200
Rising domestic consumption and falling output have turned Indonesia into a net importer of oil, forcing it to consider withdrawing from OPEC. In recent years, Jakarta has depended on gas for its export revenues. Now, the gas industry is in trouble. Output from the Arun gas fields is declining and the state oil and gas company, Pertamina, was recently forced to delay LNG shipments to its three largest customers. The government is looking for new investment in an attempt to stave off an energy crisis, but foreign companies are unhappy about business conditions there. Meanwhile, oil and gas consumption is rising rapidly thanks to a system of domestic price subsidies, which the government has been unable to end. The delay to much needed reforms in the energy sector threatens not only the oil and gas industries but the economic and political stability of the country as well. [source]

Multiple-Element Matching Reservoir Formation and Quantitative Prediction of Favorable Areas in Superimposed Basins

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 5 2010
WANG Huaijie
Abstract: Superimposed basins in West China have experienced multi-stage tectonic events and multicycle hydrocarbon reservoir formation, and complex hydrocarbon reservoirs have been discovered widely in basins of this kind. Most of the complex hydrocarbon reservoirs are characterized by relocation, scale re-construction, component variation and phase state transformation, and their distributions are very difficult to predict. Research shows that regional caprock (C), high-quality sedimentary facies (Deposits, D), paleohighs (Mountain, M) and source rock (S) are four geologic elements contributing to complex hydrocarbon reservoir formation and distribution of western superimposed basins. Longitudinal sequential combinations of the four elements control the strata of hydrocarbon reservoir formation, and planar superimpositions and combinations control the range of hydrocarbon reservoir and their simultaneous joint effects in geohistory determine the time of hydrocarbon reservoir formation. Multiple-element matching reservoir formation presents a basic mode of reservoir formation in superimposed basins, and we recommend it is expressed as T-CDMS. Based on the multiple-element matching reservoir formation mode, a comprehensive reservoir formation index (Tcdms) is developed in this paper to characterize reservoir formation conditions, and a method is presented to predict reservoir formation range and probability of occurrence in superimposed basins. Through application of new theory, methods and technology, the favorable reservoir formation range and probability of occurrence in the Ordovician target zone in Tarim Basin in four different reservoir formation periods are predicted. Results show that central Tarim, Yinmaili and Lunnan are the three most favorable regions where Ordovician oil and gas fields may have formed. The coincidence of prediction results with currently discovered hydrocarbon reservoirs reaches 97%. This reflects the effectiveness and reliability of the new theory, methods and technology. [source]