scholarly journals Effective Exploitation Potential of Shale Gas from Lower Cambrian Niutitang Formation, Northwestern Hunan, China

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3373 ◽  
Author(s):  
Han Cao ◽  
Tianyi Wang ◽  
Ting Bao ◽  
Pinghe Sun ◽  
Zheng Zhang ◽  
...  

The marine shale in the Lower Cambrian Niutitang Formation is the dominant shale-gas reservoir in northwestern Hunan, which accounts for more than 70% of unconventional energy in Hunan province. Accurately evaluating the shale-gas exploitation potential is a key to determining whether commercial exploitation standards can be met. In the literature, most existing studies have focused on evaluating the shale-gas exploitation potential based on either accumulation conditions or the shale fracability, which will lead to a gap between the real production and proven gas reserves due to the characteristics of the shale’s low permeability and low porosity. Therefore, further studies are needed to evaluate the effective shale-gas exploitation potential. To address this need, the outcrop shale samples in the Niutitang Formation were collected from the target regions, and the geological characteristics, mechanics behavior, and microstructure performance were discussed via both field data and laboratory tests. The results revealed that the shale-gas exploitation potential in the Niutitang Formation was indicated to be comparable to that of five validated shale-gas exploitation regions in the United States. To further illustrate the effective shale-gas exploitation potential, this study suggested using a comprehensive evaluation framework for this purpose, in which both accumulation condition and the shale fracability are simultaneously considered. Therefore, the shale gas reservoir in the Niutitang Formation has highly effective shale-gas exploitation potential by considering both the accumulation conditions and the shale fracability.

2012 ◽  
Vol 524-527 ◽  
pp. 1532-1536 ◽  
Author(s):  
Jin Jun Wu ◽  
Li Cai Liu ◽  
Guo Hua Zhao ◽  
Xiao San Chu

The reserves of Chinese shale gas is very rich, but still haven’t ever formed a mature technology. According to Chinese shale gas reservoir characteristics, the development technology situation and the principle of high energy gas fracturing, the research and exploration of HEGF stimulation integrated technology which is suitable for the development of Chinese shale gas reservoir need to be carried out. Through a series of analysis and study, compositing high energy gas fracturing technology achievements, this paper discusses the research idea and feasibility of the integrated technology, formed by the liquid gunpowder fracturing technology, in-fracture deeply explosive fracturing technology in low permeability oil layers, composite perforating technology, the multi-pulse fracturing technology and the hydraulic fracturing, simultaneous fracturing ,which transforms shale gas reservoir and develops shale gas. Launching field application test is suggested, and studying the way to optimize the theory and design method of integrated technology, so as to promote the development of shale gas.


2013 ◽  
Vol 706-708 ◽  
pp. 416-419
Author(s):  
Li Jun Cheng ◽  
Hong Yu Du ◽  
Zhi Guo Xie ◽  
Pei Wu Liu ◽  
Shuai Huang

Shale gas is an important unconventional energy resource. However its only achieved successful commercial exploitation in the United States and Canada. Shale gas well QY1 was carried out in southeast Chongqing.Taking this well as a case, the fracturing design optimization workflow and its practice are described in this paper. The fracturing feasibility of well QY1 was firstly determined by referencing all the physical parameters of target formation. Then the reservoir stress model was revised and reservoir stress profile was established as well. The reservoir simulation software (Eclipse) was applied to build reservoir geological model for predicting the gas production and determine the optimized permeability enhanced area (PEA). The unconventional fracturing model (UFM) was used to optimize the fluid volume and fracturing scale. And the final fracturing plan was made based on the optimized conclusions. This optimization workflow and the good result provide reliable technique support for the development of the shale gas reservoir in this area. Key Words: Shale gas, PEA, Fracture propagation model, UFM, Production predicting model, Optimization


2014 ◽  
Vol 675-677 ◽  
pp. 1485-1489
Author(s):  
Xiang Rong Luo ◽  
Shu Zhong Wang ◽  
Ze Feng Jing ◽  
Ming Ming Lv ◽  
Zhi Guo Wang ◽  
...  

The United States has taken the lead to achieve the shale gas industrial production and created a shale gas revolution throughout the world. According to the exploitation experience of the United States, the key of shale gas business development realization is to adopt horizontal well combined with fracturing technology. At present fracturing technology used commonly include multi-stage fracturing, water fracturing, refracturing, etc. China has great potential in shale gas resource, recoverable resources has 25.08×1012m3, but they are mainly located in the drought and water lack area, and the clay mineral content for shale gas reservoir is higher, the traditional water-based fracturing fluid used for shale gas development caused a lot of water consumption and serious reservoir damage, therefore, it is not suitable for shale gas reservoir conditions in China. In the process of domestic shale gas development, exploring novel fracturing and development technology is irreversible.


Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Haicheng She ◽  
Zaiqiang Hu ◽  
Zhan Qu ◽  
Yao Zhang ◽  
Hu Guo

In reviewing Chinese shale gas reserves and national policies regarding shale gas exploitation, shale gas will be of critical importance in providing clean natural gas to China. However, compared to those in the United States, the cost of shale gas extraction and the complex problems encountered in more complex and deep drilling in China are key technologies that need to be overcome. Shale wellbore wall instability is a complex problem that often occurs during drilling. During the process of drilling in shale, the complex stress and fluid-structure interactions result in the wall rock generating a strong hydration diffusion and swelling effect, which alters the stress distribution in the rock wall and deteriorates the mechanical parameters of the rock. This results in instability damage of the shale wellbore wall. In this study, the stratigraphic stress characteristics of the Fuling Shale Gas Field were initially predicted, and the shale sample phase composition and development of bedding and microcracks were analyzed using X-ray diffraction and scanning electronic microscopy. The main driving potential difference function between the drilling fluid and shale was analyzed, and a radial adsorption diffusion model of the shale plane was established. Through a laboratory study, the space time change law of the water diffusion of the shale rock was assessed as well as the rock damage evolutionary law of the elastic modulus and compressive strength with water content. Then, combined with the shale hydration stress and strength deformation theory, a damage evolutionary equation for shale with water was derived, and the shale damage evolutionary limit equation and the method of determining the collapse cycle were established. Finally, the method was applied to the Fuling Shale Gas Field, the largest shale gas field in China, and a shale wellbore collapse cycle of approximately seven days in the field was obtained. The severity of economic loss resulting from wellbore wall instability was also determined. This study provides insight and guidance for reducing the costs of shale gas reservoir well drilling and efficient development.


Author(s):  
Teng Li ◽  
Hui Gao ◽  
Chen Wang ◽  
Zhilin Cheng ◽  
Yanning Yang ◽  
...  

AbstractShale gas reservoir is a fine-grained sedimentary rock with component of clastic particles and organic matters, and the accumulation of the organic matters would determine the effective development of shale gas. The paleoclimate, detrital influx, redox of the water and paleoproductivity are effective geochemical indicators that could help to find the favorable shale gas reservoir stratum. In this study, the shale samples collected from Niutitang Formation (Northern Guizhou, China) were launched the measurements of the content of major elements and trace elements, and the characteristics of geochemical indicators were analyzed, which can be used to discuss the accumulation model of organic matters. Besides, the pore structure of shale sample controlled by the enrichment of organic matters is also discussed. The paleoclimate is dominant cold and dry, and it changes to warm and humid at the later Niutitang period, and the detrital influx also increased at the later Niutitang period; the water environment of Niutitang Formation shale presents as reductive, and the paleoproductivity of the Niutitang Formation shale is commonly high. The enrichment of organic matters in the Niutitang Formation is dominantly controlled by the redox of the water, while the hydrothermal activity and the paleoproductivity lead to the difference enrichment of organic matters in the Niutitang Formation shale. The accumulation model of organic matters also influences the characteristics of pore structure from the Niutitang Formation shale, and the pore structure could be divided into two types. The shale with high content of organic matters also features high content of quartz and pyrite, and these minerals contribute to the preservation of pore space in the shale, while that of the clay minerals is contrary. The high content of organic matters and preferable pore characteristics indicate the Niutitang Formation favors the development of shale gas, especially that for the lower Niutitang Formation.


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