Search

Abstract: CCS technology is particularly important to China due to its large and rapidly rising emissions and high dependence on fossil fuel. There is a huge basin scale theoretical CO2 storage capacity in China; however the CCS deployments will consider firstly those matched source-sink pairs with early opportunities at present. This paper presents the key results of evaluation of early opportunities for the deployment of CCS technologies within China. The proximity analysis suggests that there also are many early opportunities for CCS deployment, such as the promising EOR/EGR opportunities from using high concentration CO2 sources. The combined benefits of short distance between sources and sinks, the potential hydrocarbon revenues and low CO2 capture cost make these pairs as promising near-term CCS candidates. These near-term CCS candidates can be deployed at very low cost or even with some revenue. In this paper, several sources-sink pairs in China are analyzed in details, such as, the pairs of high purity CO2 emission sources and aquifer, co-storage of waste gas stream and depleted gas fields, IGCC and aquifer. These early opportunities will provide China the chance to develop and spread CCS technologies steadily from early stage to commercial stage. [Copyright &y& Elsevier]

Knowledge of the natural structure properties of coal seams is essential for the coal bed methane (CBM) production because of their great influence on the inner flow characteristics and permeability features of hydrocarbons and water. In this paper, a series of laboratory tests, including nondestructive low-field nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), X-ray computed tomography (CT) and core tests were carried out to characterize the physical structure properties of coal. The pore size distribution, pore type, morphological features and three-dimensional rendering of coal cleat structures are presented. The permeability changes of 7 cylindrical coal cores investigated under a varying effective stress range (0–35Mpa) reveal that coal porosity decreased linearly and coal permeability declined exponentially with the rise of stress; while under higher stress conditions, the occurrence of internal crushing and mechanical damage will result in irreversible change for porosity and permeability. Through the comprehensive analysis based on linking permeability to porosity and CT result, a basic estimation on directional cleat permeability is also realized. This method provides a preliminary but satisfactory estimation for local directional cleat permeability, which reflects that both bedding and non-bedding direction permeability owns great heterogeneity for an individual sample; but face cleat permeability always found to be the largest, and the mean bedding plane permeability value is found usually 3.01–11.68 times lower than face and butt cleat permeability. [ABSTRACT FROM AUTHOR]

There are abundant hydrocarbon resources in the deepwater region, so the exploration and development of deepwater oil and gas has become an important strategy for the Chinese petroleum industry. However, well cementing in deepwater, especially the cementing of the surface casing, is challenged due to the low temperature, which requires proper cementing accelerators to make the cement have certain strength at the early stage. Aiming to enhance the cementing quality of the surface casing, two kinds of lithium salt accelerators named LSA-1 and LSA-2 were developed in our early works based on the effects of different salts on oil well cement at low temperatures. In this paper, a comprehensive set of experiments was designed to test the effects of LSA-1 and LAS-2 on the Class-G oil well cement, including observations and measurements of the cement hydration products, the hydration heat and the developments of the static gel strength and the compressive strength. Based on these experiments, we discussed the mechanisms and performances of these two lithium salt accelerators at low temperatures. The experiment results indicate that both LSA-1 and LSA-2 can accelerate the hydration rate by advancing the hydration acceleration period and result in the earlier generation of Ca(OH) 2 and AFt. They can also induce the cement hydration products to form regular and compact gel structures, which contributes to the development of the static gel strength and the compressive strength of cement slurry at the early stage. Moreover, the two lithium salt accelerators have the characteristic of low hydration heat. This is helpful to reconcile the contradiction between the development of cement early compressive strength and the hydration heat, which can help to avoid channeling and hydrate decomposition in the strata containing gas hydrate. In general, LSA-2 has a stronger effect on accelerating hydration of oil well cement, while LSA-1 has less impact on cement hydration heat. Therefore, both LSA-1 and LSA-2 are qualified to serve as low-temperature accelerators for deepwater cementing, which are able to meet the diverse requirements of the deepwater low-temperature environment and the field cementing operation. [ABSTRACT FROM AUTHOR]

Fault-sealing capability has critical influence on coalbed methane (CBM) accumulation and preservation in coal-bearing basins. Although southern Qinshui Basin is the first commercial CBM production area in China, detailed investigation on faults evolution and its impact on gas accumulation has never been performed. In this paper, the generation time and the evolution process of the sealing capability of seven major faults in the Zhengzhuang field were evaluated by using well-logging data and 3D seismic tectonic interpretation. Results indicate that most normal faults in the Zhengzhuang field were created from Late Cretaceous to Paleogene and after the key stage of hydrocarbon-generation. Fault-sealing capability was evaluated through the vertical pressure on the faults' surface ( VPFS ), the shale gouge ratio ( SGR ) and the clay-smear potential ( CSP ), the values of which for Zhengzhuang field are −3.2 MPa to 16 MPa, 0.36 to 0.91, and 2–40 m, respectively. These values demonstrate that the fault-sealing is complex and variable when the faults present in different scales or different positions in the faulting system. In the Zhengzhuang field, almost all faults exhibit good lateral sealing capability ( LSC ) with high values of SGR (>0.6) and CSP (>15 m) during fault evolution. Therefore, the current gas contents are primarily related to the vertical sealing capability ( VSC) but not to the LSC of the faults. The VSC of the fault varies with the different stages during the fault evolution. In the Late Cretaceous-Paleogene, a key stage for gas dissipation, almost all faults possess low VSC, which caused generally low gas content (<22.4 m 3 /t) near the faults. In contrast, the gas content that was not affected by faults is commonly >25 m 3 /t. In the Neogene-Quaternary, the VSC was variable for different faults. For the faults with low VSC, they would gradually lead to low gas content. The results showed that the VSC positively correlated with the current gas contents near the faults in the Zhengzhuang field, southern Qinshui Basin, North China. [ABSTRACT FROM AUTHOR]

In view of the growing demand of resources in China, it has started looking towards the faraway land to fulfil its needs. The presence of hundreds of skyscrapers in large cities of China show the clear picture of the increased demand for resources, especially the energy resources, in the country. The Central Asian region has become a desired destination for the source of energy in the recent times for China. The proximity to these countries, ethnic connection of Xinjiang region of China to Central Asia, presence of large energy resources and regional stability are some of the reasons behind it. The link between these two regions are there from the times of the presence of ancient Silk Road. The revival of this route in recent years is one of the way to increase the economic benefits of both the regions. So the objective of this paper is to highlight the recent demands of resources in China because of the pressure mounted by inner peripheral regions and the increased need of the country for the new sources of energy security. The policy adopted by the country to deal with the Central Asian nations and the development of new routes will be discussed. The bilateral trade pattern will also be discussed to show the effect of the development of close transport links between China and Central Asian region. [ABSTRACT FROM AUTHOR]

Abstract: Based on analysis of the characteristics of unconventional hydrocarbon resources, this paper assesses the potential for unconventional hydrocarbons in China, summarizes the key technical progress in exploration and development, and discusses the prospects and developing strategies of unconventional hydrocarbons. The resources of unconventional oil and gas in China are abundant. The recoverable tight gas ranges from 8.8×1012 m3 to 12.1×1012 m3, the recoverable shale gas is from 15×1012 m3 to 25×1012 m3, the recoverable coalbed methane 10.9×1012 m3, the recoverable tight oil from 13×108 t to 14×108 t, and the recoverable shale oil 160×108 t. There is also some resource potential for oil sand. Such key techniques as the full-digital seismic exploration, low permeability and low resistivity reservoirs identification have been developed and their applications in oil and gas fields have achieved good results. Tight gas and tight oil are the most realistic resources to develop in China and the development and utilization of coalbed methane and shale gas are at a pioneer stage. In the next ten or twenty years, the production of unconventional hydrocarbon in China will increase considerably and play a major role in national hydrocarbon resources. [Copyright &y& Elsevier]

Abstract: Natural gas exploration and discovery of hydrocarbons in the Xujiahe Formation in the Sichuan Basin are mainly concentrated in the Xu-2, 4 and 6 Members. The discovered gas reservoirs are characterized by a low filling degree, high water saturation in lower intervals, low levels of produced reserves and a limited number of gas-bearing reservoirs. The Xu-1, 3 and 5 Members are identified as source rocks. Based on the study of natural gas accumulations and several gas production wells in the Xu-1, 3 and 5 Members, this paper proposes that large scale sand bodies are developed in the Xu-1, 3 and 5 Members in the northwest, southwest and central parts of the Sichuan Basin. In each member, the favorable gas bearing area is about 5 000-11 000 km2, the reservoir rocks have good continuity with single layer extensions of up to 15-20 km. It is believed that these sand bodies have favorable conditions for gas accumulation within source kitchens to form lithologic or structural-lithologic gas reservoirs and have better accumulation potential and higher gas-bearing abundance than that of the Xu-2, 4 and 6 Members. Exploration practices have revealed that economic gas reserves may be generated. It is suggested that more efforts be made to study the gas accumulation conditions in the Xu-1, 3 and 5 Members (especially the Xu-3 and Xu-5 Members) and more exploration work be conducted in these strata. [Copyright &y& Elsevier]

Abstract: With Sichuan Basin as focus, this paper introduces the depositional environment, geochemical and reservoir characteristics, gas concentration and prospective resource potential of three different types of shale in China: marine shale, marine-terrigenous shale and terrigenous shale. Marine shale features high organic abundance (TOC: 1.0%–5.5%), high-over maturity (R o: 2%–5%), rich accumulation of shale gas (gas concentration: 1.17–6.02 m3/t) and mainly continental shelf deposition, mainly distributed in the Paleozoic in the Yangtze area, Southern China, the Paleozoic in Northern China Platform and the Cambrian-Ordovician in Tarim Basin; Marine-terrigenous coalbed carbonaceous shale has high organic abundance (TOC: 2.6%–5.4%) and medium maturity (R o: 1.1%–2.5%); terrigenous shale in the Mesozoic and Cenozoic has high organic abundance (TOC: 0.5%–22.0%) and mid-low maturity (R o: 0.6–1.5%). The study on shale reservoirs in the Lower Paleozoic in Sichuan Basin discoveried nanometer-sized pores for the first time, and Cambrian and Silurian marine shale developed lots of micro- and nanometer-sized pores (100–200 nm), which is quite similar to the conditions in North America. Through comprehensive evaluation, it is thought that several shale gas intervals in Sichuan Basin are the practical targets for shale gas exploration and development, and that the Weiyuan-Changning area in the Mid-South of Sichuan Basin, which is characterized by high thermal evolution degree (R o: 2.0%–4.0%), high porosity (3.0%–4.8%), high gas concentration (2.82–3.28 m3/t), high brittle mineral content (40%–80%) and proper burial depth (1500–4500 m), is the core area for shale gas exploration and development, the daily gas production for Well Wei 201 is 1×104–2×104 m3. [Copyright &y& Elsevier]

Abstract: The Yuka depression is located in the north margin in Qaidam Basin, Qaidam Basin is an interior formed primarily in the Mesozoic and Cenozoic. There are extensive distribution of good source rocks of middle Jurassic, which have undergone non-uniform uplift, twisting and deep burying. There are different hydrocarbon generation (HG) evolutions. We have studied the history of burying, heating, and hydrocarbon generation of the Jurassic source rocks not just on the basis of tectonic disturbance and deep burying in detail. Meanwhile, Combining with fluid inclusion measurements and the numerical simulation of EASY%Ro, We analysis the evolution process, the tectonic stages and the intensity of the HG of middle Jurassic source rock. The hydrocarbon generation occurred in Yanshanian and Early Himalayan since the middle Jurassic formation. The paper discusses tarp formation and destroys of the oil & gas in Yuka depression. At last, we suggest that the thrust fault of Late Himalayan must be pay more attention, .and the middle or small sizes of oil & gas fields will be discovered in the future exploration. [Copyright &y& Elsevier]