scholarly journals Stress sensitivity evaluation of ultra-low permeability sandstone reservoir and its influence on oilfield development

2021 ◽  
Vol 292 ◽  
pp. 01027
Author(s):  
Xin Bai ◽  
Chunfen Guo ◽  
Xingli Yang ◽  
Xi Liu
Keyword(s):  
Water Injection ◽  
Confining Pressure ◽  
Stress Sensitivity ◽  
Low Permeability ◽  
Oil Well ◽  
Pressure Stage ◽  
Bottom Hole ◽  
Sensitivity Evaluation ◽  
Permeability Damage ◽  
Sandstone Reservoir

Luohe ultra-low permeability sandstone reservoir is a hot block in Yanchang oilfield, which is a potential point for increasing production and reservoir. In view of the current situation that there is no unified stress sensitivity evaluation standard for ultra-low permeability sandstone in the study area, taking the ultra-low permeability sandstone in Luohe district as the research object, the stress sensitivity evaluation of ultra-low permeability sandstone is carried out by using experimental analysis as the main means. The results show that it is more accurate to evaluate porosity by using pore stress sensitivity coefficient instead of pore compressibility coefficient. With the increase of net overburden pressure, the porosity stress sensitivity decreases gradually; the permeability stress sensitivity is evaluated by variable confining pressure. With the increase of confining pressure, the permeability damage decreases. With the decrease of confining pressure, the permeability damage increases, but it can not recover to the original value, so the permeability damage is irreversible; in the low bottom hole pressure stage, stress sensitivity has a greater impact on oil well productivity, while in the high bottom hole pressure stage, stress sensitivity has a smaller impact on oil well productivity; advanced water injection can reduce the adverse effect of stress sensitivity on the development of ultra-low permeability sandstone and maximize the economic benefits. The research results clarify the method of stress sensitivity evaluation, and provide guidance for efficient water injection in the next step.

Research on Stress Sensitivity of Low Permeability Sand Stone Reservoir

2011 ◽  
Vol 317-319 ◽  
pp. 2432-2435
Author(s):  
Yu Xue Sun ◽  
Fei Yao ◽  
Jing Yuan Zhao
Keyword(s):  
Plastic Deformation ◽  
In Situ Stress ◽  
Stress Sensitivity ◽  
Oil Field ◽  
Low Permeability ◽  
High Permeability ◽  
Permeability Changes ◽  
Loading And Unloading ◽  
Sandstone Reservoir

In the process of low-permeability sandstone reservoir exploitation, stress sensitivity takes place with the effective stress rises gradually, which will cause permeability decline. Allowing to the condition of in-situ stress, the study and experiment on the rock core in Jilin oil field Fuxin326 oil layer are presented. The experimental results show that the stress sensitivity of this oil layer is small; the regularity of permeability changes is in accordance with exponential function. The stress sensitivity of high permeability core is larger than that of low permeability core. Moreover, experimental and theoretical analysis shows that low permeability core has a larger permeability loss than high permeability core in loading and unloading process where elastic plastic deformation of rock will happen, which is the major reason that permeability loss can not return completely.

A Study of Influential Factors of Advance Water Injection in Extra-Low Permeability Reservoir

2014 ◽  
Vol 487 ◽  
pp. 255-258
Author(s):  
Jin Gang He ◽  
Kao Ping Song ◽  
Jing Yang ◽  
Bao Gang Sun ◽  
Si Chen ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Early Stage ◽  
Retention Rate ◽  
Water Injection ◽  
Stress Sensitivity ◽  
Influential Factors ◽  
Low Permeability ◽  
Formation Pressure ◽  
Low Permeability Reservoir ◽  
Start Up

This paper study on the permeability, start-up pressure gradient and stress sensitivity of advance water injection in extra-low permeability reservoir in Fuyu Oil layer of Daqing Oilfield. Experimental results show that the reasonable formation pressure level should be at about 120% in the advance water injection experiment, advanced water injection in the the early stage have higher oil production, the water breakthrough, earlier than synchronous water injection has certain inhibitory effect of water cut rise; Under the premise of advance water injection can overcome the start-up pressure, the lower the level of the reservoir permeability, the higher improve recovery efficiency of the proportion; permeability retention rate increase by about 22% with 5×10-3μm2 core and effectively overcome the stress sensitivity of low permeability reservoir damage; Advanced water injection can overcome stress sensitivity and restoring formation pressure, all that influence the start-up pressure gradient, which significantly reduce the start-up pressure gradient.

Effect of Test Mode on Stress Sensitivity Evaluation of Full-Diameter Volcanic Rock

2013 ◽  
Vol 718-720 ◽  
pp. 525-531
Author(s):  
Juan Wang ◽  
Ping Guo ◽  
Cai Zhen Peng ◽  
Fang Wang
Keyword(s):  
Internal Pressure ◽  
Volcanic Rock ◽  
Confining Pressure ◽  
Stress Sensitivity ◽  
The Other ◽  
High Permeability ◽  
Pore Connectivity ◽  
Test Mode ◽  
Sensitivity Evaluation ◽  
Study Results

some reservoir property change which occurs during reservoir development has been studied, however, the study about the effect of test mode on stress sensitivity evaluation of full-diameter volcanic rock is few since the volcanic gas reservoir in Da-qing is buried deeply and the properties and flow mechanics are extremely complex. Therefore, there are two different test modes for stress sensitivity to study the effect of test mode on stress sensitivity evaluation. One of the test modes is to keep the internal pressure constant and change the confining pressure and the other is to change the internal pressure and keep the confining pressure constant. The study results are as follows: (a) the permeabilitys variation law at different test mode is similar when the net stress varies. There are two type, one is sensitive with high permeability since for well development of micro-fracture and pore connectivity, the other is not sensitive with high permeability since for the weak pore connectivity and micro-fracture; (b) the permeability could decrease with times of pressure cycling , so, the times of flow/shut in operation should be decreased as few as possible; (c) the relative variation of permeability in the mode of changing confining pressure is smaller than it in changing internal pressure, which means the stress sensitivity of changing confining pressure is weaker; (d) the results of changing internal pressure should be used since the test mode is more similar with the actual operation. The results are significant for gas-water RPs accurate determination and efficient development of volcanic reservoirs.

scholarly journals Research on optimization of development technology policy for low-permeability and low-pressure reservoir in Yangbaishan Block

2019 ◽  
Vol 118 ◽  
pp. 01029
Author(s):  
Xiulan Zhu ◽  
Yanlong Ran ◽  
Yidong Yuan
Keyword(s):  
Technology Policy ◽  
Water Injection ◽  
Low Pressure ◽  
Energy Deficit ◽  
Low Permeability ◽  
Oil Well ◽  
Production Ratio ◽  
Natural Energy ◽  
Well Pattern ◽  
Development Technology

There are poor physical properties and insufficient natural energy in the low-permeability and low-pressure reservoir of the Yangbaishan Block. Early this reservoir was mined by natural energy with a serious producing energy deficit. Subsequently, it was developed with mild water injection. During the water injection development, water quickly slid into the oil well along the crack, oil production decreased sharply and water content increased rapidly in the oil well, the water flooded well and the ineffective well gradually increased. Therefore, based on the reservoir geological characteristics, principle of injection and production balance is used to optimize reasonably for the development technology policy. Research indicates that the square inverted nine spot flooding pattern is recommended with a reasonable injection well direction of NE 72°and technical well spacing of 150 m. Reasonable injection-production ratio should be 2.16, reasonable technical well pattern density is 23 wells per square kilometer, and the average daily water injection rate of single well should be 11 m3. When injection-production system and injection proration are improved, water drive controlled degree is expected to increase by 16 %. This research can provide reference for the efficient development and safety management of other similar reservoirs.

Geological Characteristics and Waterflooding Strategy for Yuanshi Low Permeability Sandstone Reservoir

2012 ◽  
Vol 594-597 ◽  
pp. 134-139
Author(s):  
Wei Zhu ◽  
Zi Jian Cao
Keyword(s):  
Development Strategy ◽  
Flow Behavior ◽  
Water Injection ◽  
Low Permeability ◽  
Well Spacing ◽  
The Development Strategy ◽  
Engineering Measures ◽  
Pressure Water ◽  
Sandstone Reservoir ◽  
Development Result

Core test data from 10 wells indicate that the sandstone reservoir in Yuanshi oilfield is characterized by low permeability, thin pore throat, high clay mineral content, and strong sensitivity, which are likely to cause reservoir damage and affect development result. Based on the characteristics of water-sensitive, velocity-sensitive low permeability reservoir as well as non-Darcy flow behavior, the development strategy of high pressure water injection and cyclic water injection has been formulated with the assistance of engineering measures such as fracturing and reducing well spacing.

A New Mathematical Model of Tight Formation for Productivity Transient Analysis with Additional Gas Driving

2021 ◽  
Author(s):  
Xiaoliang Zhao ◽  
Jiali Zhang ◽  
Xinwei Liao
Keyword(s):  
Transient Analysis ◽  
Phase Distribution ◽  
Gas Injection ◽  
Stress Sensitivity ◽  
Carbonate Reservoir ◽  
Low Permeability ◽  
Analysis Model ◽  
Damage Coefficient ◽  
Single Well ◽  
Permeability Damage

Abstract During the gas injection development of low-permeability carbonate reservoirs, due to the complexity of the reservoir and the complexity of the fluid phases, the current productivity evaluation methods are no longer applicable. In this paper, considering factors such as fracture characteristics, stress sensitivity, and phase distribution, a low-permeability carbonate reservoir gas injection development productivity transient analysis model is established. The results of the study show that the larger the value of permeability damage coefficient, the stronger the curve of the production curve will bend toward the pressure axis. This is because the larger the value of permeability damage coefficient, the more severe the stress sensitivity of the formation is, which shows that rock deformation has an important impact on production. When two phases appear at the bottom of the well, the seepage resistance increases due to the two-phase flow, which in turn causes the productivity of a single well to rapidly decrease. With the decrease of bottom hole pressure, this resistance will increase significantly and the productivity of a single well will decline rapidly.

Stress-sensitive permeability of matrix cores and artificially fractured cores with non-proppant-filled fractures under high-pressure conditions

Geophysics ◽  
2021 ◽  
pp. 1-102
Author(s):  
Ren-Shi Nie ◽  
Zheng Wang ◽  
Zhangxin Chen ◽  
An-Cheng Wang ◽  
Chang-Hong Zhou ◽  
...  
Keyword(s):  
High Pressure ◽  
Internal Pressure ◽  
Confining Pressure ◽  
Stress Sensitivity ◽  
Curve Analysis ◽  
Test Method ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Permeability Damage ◽  
Fractured Sandstone

Stress-sensitive permeability (SSP) influences gas well productivity and is a crucial element influencing gas reservoir development. SSP for high-pressure fractured gas reservoirs with an initial reservoir pressure of more than 20 MPa has never been comprehensively evaluated to the best of our knowledge. SSP experiments with special procedures were designed by adopting the variable confining pressure (VCP) and variable internal pressure (VIP) methods. VCP is a test method in which confining pressure is altered and a constant internal pressure is maintained for the experimental core holder. VIP is a test method in which internal pressure is changed and a constant confining pressure is maintained. A four-stage curve analysis method was developed to perform regressions on semi-logarithmic curves and exponential curves of experimental data. A method to evaluate the SSP was presented using stress sensitivity coefficients obtained via regressions. A calculation approach for determining the degrees of permeability damage and permeability recovery was also proposed. Six matrix cores and six cores with artificial fractures from a high-pressure fractured sandstone gas reservoir were tested using the two methods. The SSP curves for high-pressure reservoirs were characterized by four-stage variation trends, which differentiated with low-pressure reservoirs with an initial reservoir pressure less than 20 MPa. The stress sensitivity of the VCP method was stronger than that of the VIP method. The core samples mainly showed a “Medium” / “Medium-Strong” stress sensitivity under low/high effective stress conditions. Compared with matrix cores, fractured cores showed stronger stress sensitivity owing to its strong plasticity and weak elasticity. The maximum permeability damage degree reached 99.67% and the minimum permeability recovery was only 6.9%. The presented method of experimental design, four-stage curve analysis, stress sensitivity evaluation and the summarized findings in this paper can provide references for future studies on SSP in high-pressure fractured sandstone gas reservoirs.

scholarly journals HYDRAULIC FRACTURING OF AN ARENITIC RESERVOIR BASED IN THE PERKINS-KERN MODEL USING A STIMPLAN SIMULATOR

2021 ◽  
Vol 15 (1-2) ◽  
pp. 1-12
Author(s):  
G. B. Silva ◽  
L. O. A. Rojas ◽  
J. A. Soares
Keyword(s):  
Hydraulic Fracturing ◽  
Oil Wells ◽  
Reservoir Rock ◽  
Fracture Model ◽  
Low Permeability ◽  
Oil Well ◽  
Geological Model ◽  
Depth Of Penetration ◽  
Sandstone Reservoir ◽  
Over Time

Hydraulic fracturing consists of a technique capable of stimulating oil wells that have suffered a decline in production over time. It also allows the production in reservoirs that have low permeability through the creation of a network of channels in the rock. In this context, this article aims to numerically simulate the hydraulic fracturing applied in a sandstone reservoir according to data extracted from an oil well located in the Aracaju City field of the Sergipe-Alagoas Basin. To complete this study, a geological model of the reservoir was generated. Subsequently, a fracture was created in the rock-reservoir in a controlled manner using the Perkins and Kern fracture model. Results show that the fracture takes a satisfactory proportion in the reservoir rock, reaching a depth of penetration equivalent to 695.7 meters.

Analysis of the channeling of water injection in low permeability reservoirs with interlayer considering the seepage–stress coupling

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ji Youjun ◽  
K. Vafai ◽  
Huijin Xu ◽  
Liu Jianjun
Keyword(s):  
Water Injection ◽  
Simulation Method ◽  
Stress Sensitivity ◽  
Injection Rate ◽  
Water Flooding ◽  
Low Permeability ◽  
Content Type ◽  
Main Injection ◽  
Low Permeability Reservoirs ◽  
The Impact

Purpose This paper aims to establish a mathematical model for water-flooding considering the impact of fluid–solid coupling to describe the process of development for a low-permeability reservoir. The numerical simulation method was used to analyze the process of injected water channeling into the interlayer. Design/methodology/approach Some typical cores including the sandstone and the mudstone were selected to test the permeability and the stress sensitivity, and some curves of the permeability varying with the stress for the cores were obtained to demonstrate the sensitivity of the formation. Based on the experimental results and the software Eclipse and Abaqus, the main injection parameters to reduce the amount of the injected water in flowing into the interlayer were simulated. Findings The results indicate that the permeability of the mudstone is more sensitive to the stress than sandstone. The injection rate can be as high as possible on the condition that no crack is activated or a new fracture is created in the development. For the B82 block of Daqing oilfield, the suggested pressure of the production pressure should be around 1–3MPa, this pressure must be gradually reached to get a higher efficiency of water injection and avoid damaging the casing. Originality/value This work is beneficial to ensure stable production and provide technical support to the production of low permeability reservoirs containing an interlayer.

scholarly journals Study on the sensitivities and damage mechanisms of ultra-low permeability sandstone reservoirs: taking Chang 6 reservoir in Jingbian oilfield as an example

2020 ◽  
Vol 194 ◽  
pp. 01037
Author(s):  
Xiulan Zhu ◽  
Yanlong Ran ◽  
Zhanjun Chen ◽  
Tai Xu ◽  
Shengling Jiang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Ordos Basin ◽  
Small Hole ◽  
Low Permeability ◽  
Thin Sections ◽  
Acid Sensitivity ◽  
Water Sensitivity ◽  
Sensitivity Evaluation ◽  
Sandstone Reservoir ◽  
Sandstone Reservoirs

This paper takes the ultra-low permeability sandstone reservoir of Jingbian oilfield in Ordos Basin as the research object, analyzes the petrological characteristics, diagenesis, physical characteristics and pore structure characteristics of the reservoir, and carries out reservoir sensitivity evaluation by using rock casting thin sections, X-ray diffraction, and sensitive flow experiments. The research results show that the ultra-low permeability Chang 6 sandstone reservoir has weak velocity sensitivity, medium-weak water sensitivity, weak salt sensitivity, weak alkali sensitivity and strong acid sensitivity; the damage mechanism of reservoir sensitivity mainly depends on the composition of clay minerals and pore structure after diagenesis. The clay mineral content from high to low is chlorite, illite, a small amount of illite / smectite layer, and kaolinite, of which the chlorite content is as high as 75 %; the reservoir has poor physical properties, the types of small hole-thin throat and small hole-fine throat. The reservoir is prone to blockage such as bridge plugging. Therefore, ultra-low permeability sandstone reservoirs are prone to different degrees of sensitivity. The reservoir characteristics are consistent with the reservoir sensitivity evaluation results.

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