scholarly journals Determination of the Hydration Damage Instability Period in a Shale Borehole Wall and Its Application to a Fuling Shale Gas Reservoir in China

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Haicheng She ◽  
Zaiqiang Hu ◽  
Zhan Qu ◽  
Yao Zhang ◽  
Hu Guo
Keyword(s):  
Shale Gas ◽  
Drilling Fluid ◽  
Economic Loss ◽  
Wall Rock ◽  
The United States ◽  
Complex Problem ◽  
Evolutionary Equation ◽  
Gas Reservoir ◽  
Gas Field ◽  
Shale Gas Reservoir

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.

The Practice and Cognition of Hydraulic Fracturing Technique for Shale Gas Reservoir in Southeast Chongqing

2013 ◽  
Vol 706-708 ◽  
pp. 416-419
Author(s):  
Li Jun Cheng ◽  
Hong Yu Du ◽  
Zhi Guo Xie ◽  
Pei Wu Liu ◽  
Shuai Huang
Keyword(s):  
Shale Gas ◽  
Energy Resource ◽  
The United States ◽  
Simulation Software ◽  
Propagation Model ◽  
Physical Parameters ◽  
Stress Profile ◽  
Gas Reservoir ◽  
Reliable Technique ◽  
Shale Gas Reservoir

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

A Review of Shale Gas Exploitation Technology

2014 ◽  
Vol 675-677 ◽  
pp. 1485-1489
Author(s):  
Xiang Rong Luo ◽  
Shu Zhong Wang ◽  
Ze Feng Jing ◽  
Ming Ming Lv ◽  
Zhi Guo Wang ◽  
...  
Keyword(s):  
United States ◽  
Shale Gas ◽  
Mineral Content ◽  
The United States ◽  
Gas Reservoir ◽  
Shale Gas Reservoir ◽  
Multi Stage ◽  
Reservoir Conditions ◽  
Development Technology ◽  
Recoverable Resources

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.

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 ◽  
...  
Keyword(s):  
Shale Gas ◽  
Lower Cambrian ◽  
Comprehensive Evaluation ◽  
The United States ◽  
Evaluation Framework ◽  
Hunan Province ◽  
Low Permeability ◽  
Gas Reservoir ◽  
Shale Gas Reservoir ◽  
Niutitang Formation

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.

scholarly journals Experimental Research of the Influence of Microfracture Morphology on Permeability of Shale Rock

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Xiaohe Huang ◽  
Yunqian Long ◽  
Yuyi Wang ◽  
Ming Yue
Keyword(s):  
Shale Gas ◽  
Initial Permeability ◽  
Gas Reservoir ◽  
Exponential Relationship ◽  
Gas Field ◽  
Fracture Width ◽  
Fracture Length ◽  
Shale Gas Reservoir ◽  
Shale Rock ◽  
Seepage Characteristics

Hydraulic fracturing is currently one of the main technical methods of shale gas exploitation. The permeability variation of shale gas reservoir after fracturing is inevitable, while the influence of fracture length and fracture width on permeability and seepage characteristics of shale rock is a mystery. Besides, the stress sensitivity characteristics of shale rock, derived from different initial permeability, with the same permeability after fracturing are also ambiguous. To this end, a series of seepage characteristic experiments related to different fracture parameters are carried out with the black shale of the Longmaxi Formation in Sichuan gas field as the research target. The results show that the fracture length and fracture width have a good exponential relationship with the corresponding permeability of the reformed shale rock, and the contribution of the fracture width to shale permeability is much greater than that of the fracture length. In addition, the nonlinear seepage characteristics of shale rock are gradually significant with the reduction of fracture length and fracture width. Taking the primitive effective stress (10 MPa) as a critical point, the permeability of shale with large initial permeability decreased by 26.4%, which is about twice as much as that of shale rock with small initial permeability (14.9%) in the selected pressure loading stage, owing to the difference of fracture width inside the shale rock. The permeability of the shale rock with a large initial permeability is restored by 14.7%, while the shale rock with a small initial permeability is only recovered to 5.2% in the pressure unloading stage, which is attributed to the closure of fractures, especially the loss of fracture width. This research can provide some new insights for the production prediction of shale gas reservoir after fracturing.

A Probe into Branch Fracture of Shale Gas Reservoir in China

2012 ◽  
Author(s):  
Chen Mingzhong ◽  
Qian Bing ◽  
Ou Zhilin ◽  
Zhang juncheng ◽  
Jiang Hai ◽  
...  
Keyword(s):  
Shale Gas ◽  
Gas Reservoir ◽  
Shale Gas Reservoir
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