New Method for Evaluating Rock Stress Sensitivity for Low-Permeability Tight Gas Reservoirs

2017 ◽  
Vol 53 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Zhaopeng Yang ◽  
Hao Yang ◽  
Heping Chen ◽  
Hongqiang Zhang
Keyword(s):  
Stress Sensitivity ◽  
New Method ◽  
Low Permeability ◽  
Tight Gas ◽  
Rock Stress ◽  
Gas Reservoirs ◽  
Tight Gas Reservoirs

scholarly journals Gas-Water Flow Behavior in Water-Bearing Tight Gas Reservoirs

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Renyi Cao ◽  
Liyou Ye ◽  
Qihong Lei ◽  
Xinhua Chen ◽  
Y. Zee Ma ◽  
...  
Keyword(s):  
Water Saturation ◽  
Flow Behavior ◽  
Stress Sensitivity ◽  
Gas Production ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Threshold Pressure Gradient ◽  
Tight Gas Reservoirs ◽  
Gas Recovery ◽  
Mobile Water

Some tight sandstone gas reservoirs contain mobile water, and the mobile water generally has a significant impact on the gas flowing in tight pores. The flow behavior of gas and water in tight pores is different than in conventional formations, yet there is a lack of adequate models to predict the gas production and describe the gas-water flow behaviors in water-bearing tight gas reservoirs. Based on the experimental results, this paper presents mathematical models to describe flow behaviors of gas and water in tight gas formations; the threshold pressure gradient, stress sensitivity, and relative permeability are all considered in our models. A numerical simulator using these models has been developed to improve the flow simulation accuracy for water-bearing tight gas reservoirs. The results show that the effect of stress sensitivity becomes larger as water saturation increases, leading to a fast decline of gas production; in addition, the nonlinear flow of gas phase is aggravated with the increase of water saturation and the decrease of permeability. The gas recovery decreases when the threshold pressure gradient (TPG) and stress sensitivity are taken into account. Therefore, a reasonable drawdown pressure should be set to minimize the damage of nonlinear factors to gas recovery.

scholarly journals Pre-acid system for improving the hydraulic fracturing effect in low-permeability tight gas reservoir

2021 ◽  
Vol 11 (4) ◽  
pp. 1761-1780
Author(s):  
Nianyin Li ◽  
Fei Chen ◽  
Jiajie Yu ◽  
Peihong Han ◽  
Jia Kang
Keyword(s):  
Hydraulic Fracturing ◽  
Filter Cake ◽  
Low Permeability ◽  
Tight Gas ◽  
Acid System ◽  
Fracturing Fluid ◽  
Gas Reservoirs ◽  
Tight Gas Reservoirs ◽  
Acid Fracturing ◽  
Performance Requirements

AbstractHydraulic fracturing is an important technical means to improve the development effect of low-permeability oil and gas reservoirs. However, for low pressure, low-permeability, tight, and high-clay sandstone gas reservoirs, conventional propped fracturing can cause serious damage to the reservoir and restrict the fracturing effect. The pre-acid fracturing technology combines acid treatment technology with sand-fracturing technology. A pre-acid system that meets special performance requirements is injected before fracturing. The pre-acid reduces the formation fracture pressure and removes clay damage. During acid flowback, the fracturing fluid is promoted to break the gel, dissolve the fracturing fluid residue and polymer filter cake, clean the supporting cracks, and effectively improve the fracturing effect. This study analyzes the process principle and technical advantages of the pre-acid fracturing technology based on the laboratory evaluation of the fracturing damage mechanism of low-permeability tight gas reservoirs. To meet the performance requirements of low-permeability tight gas reservoirs and pre-acid fracturing technology, a set of polyhydrogen acid system with long-lasting slow reactivity, low damage, and low corrosion was developed and used as the pre-fracturing acid. The acid system is mainly composed of the main agent SA601 and the auxiliary agent SA701. Then, on the basis of laboratory experiments, this acid system is used as the fracturing pre-acid to evaluate the fracturing improvement effect. The results show that the fracturing fluid system can better dissolve the fracturing fluid filter cake and remove the fracturing fluid damage.

scholarly journals Well Testing Model of Multiple Fractured Horizontal Well with Consideration of Stress-Sensitivity and Variable Conductivity in Tight Gas Reservoirs

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Zhongwei Wu ◽  
Chuanzhi Cui ◽  
Zhen Wang ◽  
Yingfei Sui ◽  
Peifeng Jia ◽  
...  
Keyword(s):  
Early Time ◽  
Stress Sensitivity ◽  
Late Time ◽  
Well Testing ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Pressure Derivative ◽  
Tight Gas Reservoirs ◽  
Fractured Horizontal Wells ◽  
Variable Conductivity

Multiple fractured horizontal wells have been widely used to develop unconventional tight gas reservoirs. Currently, many well testing models were established to study the performance of fractured horizontal wells in tight gas reservoirs. However, none of these models thoroughly takes stress-sensitivity of natural fractures and variable conductivity of artificial fractures into consideration. Based on the consideration of stress-sensitivity of natural fractures and variable conductivity of artificial fractures, a novel well testing model for fractured horizontal well in tight gas reservoirs is proposed. And the semianalytical solution of this new model is obtained by dividing the artificial fracture into different segments under the integrative methods of Laplace transformation, point source function, perturbation theory, superposition principle, and Stehfest numerical inversion. After validation, the semianalytical solution is consistent with that of Zerzar’s model (2004). Also, typical pressure and pressure derivative curves are plotted. According to typical curves, seven regimes can be derived, namely, bilinear flow, linear flow, early-time pseudoradial flow, biradial flow, intermediate-time pseudoradial flow, and pseudo-steady state interporosity flow, and late-time pseudoradial flow can be identified. In addition, this paper analyzes the impact on pressure and pressure derivative curves exerted by variable conductivity and stress-sensibility. The results show that variable conductivity mainly affects the early flow regimes, including bilinear flow, linear flow, and early-time radial flow, while the stress-sensitivity mainly affects the later flow regimes, including intermediate-time pseudoradial flow, pseudo-steady state interporosity flow, and late-time pseudoradial flow. The typical curves will ascend with the increasing of stress-sensitivity coefficient. The research provides a method for precise prediction of formation parameters and has a significant impact on the tight gas reservoir development.

scholarly journals Rock stress sensitivity in low-permeability gas reservoirs and its impact on productivity

2020 ◽  
Vol 570 ◽  
pp. 022021
Author(s):  
Jian Xiong ◽  
Haiying Wang ◽  
Linlin Huang ◽  
Hui Zhang ◽  
Xiangjun Liu ◽  
...  
Keyword(s):  
Stress Sensitivity ◽  
Low Permeability ◽  
Rock Stress ◽  
Gas Reservoirs

Effect of connate water on stress sensitivity of tight gas reservoirs

2019 ◽  
pp. 1-15
Author(s):  
Yang Zhaopeng ◽  
Wu Zhiwei ◽  
Li Yinghua ◽  
Yang Heng ◽  
Lu Tianyuan
Keyword(s):  
Stress Sensitivity ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Gas Reservoirs ◽  
Connate Water

Productivity calculating method in tight gas reservoirs considering the stress sensitivity

2022 ◽  
Vol 15 (2) ◽  
Author(s):  
Jie He ◽  
Xiangdong Guo ◽  
Hongjun Cui ◽  
Kaiyu Lei ◽  
Yanyun Lei ◽  
...  
Keyword(s):  
Stress Sensitivity ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Gas Reservoirs ◽  
Calculating Method
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