scholarly journals The study on experimental method of fluid stress sensitivity of low permeability in tight reservoir

2021 ◽  
Author(s):  
Xiao Lin ◽  
Liu Xue-wei ◽  
Shao Long-kan ◽  
Wang Shao-peng ◽  
Xiao Pu-fu ◽  
...  
Keyword(s):  
Axial Stress ◽  
Fluid Pressure ◽  
Axial Loading ◽  
Stress Sensitivity ◽  
Low Permeability ◽  
Production Test ◽  
Sensitivity Curve ◽  
Tight Reservoir ◽  
Opening Stage ◽  
Field Production

AbstractAccording to the industry standard, low permeability and tight reservoir are highly stress-sensitive in laboratory tests. However, this phenomenon has not been effectively confirmed in the field production test. For this reason, a method to measure stress sensitivity by axial loading is proposed. By loading fixed axial stress, the measurement method achieves the effect of equivalent preloading fluid pressure. Meanwhile, the equivalent theoretical curve can be obtained by translating the curve. Through this method, the stress sensitivity of the core with microfracture is studied. According to the results, the stress sensitivity of the cores can be divided into two stages: the first stage is the non-opening stage of microfractures, in which the stress sensitivity is weak; the second stage is the opening stage of microfractures, in which the stress sensitivity increases sharply. When the permeability changes significantly, the corresponding pressure is the microfracture's opening pressure. In addition, if the abscissa of the experimental results corresponds to the field production data, the field stress sensitivity curve of the field reservoir can be obtained. Conventional stress sensitivity test shows that the four cores in the study block exhibit medium to strong stress sensitivity. According to the stress sensitivity curve analysis after curve translation, the stress sensitivity of the reservoir is about 25% in the elastic production stage, which is classified as weak stress sensitivity. This conclusion can effectively support the phenomenon of the unobvious stress sensitivity in the field production of low permeability and tight reservoirs.

Experimental Comparison Study of Stress Sensitivity at Different Levels of Permeability Core

2012 ◽  
Vol 594-597 ◽  
pp. 76-79
Author(s):  
Yong Chao Xue ◽  
Lin Song Cheng ◽  
Chen Li
Keyword(s):  
Loss Rate ◽  
Stress Sensitivity ◽  
Laboratory Simulation ◽  
Experimental Comparison ◽  
Type Model ◽  
Low Permeability ◽  
Sensitivity Curve ◽  
High Permeability ◽  
Low Permeability Reservoir ◽  
Bottom Hole Flowing Pressure

Whether the stress sensitivity in the mid-high permeability is stronger than that in the low permeability reservoir is current hot debate, aimed at this question. 14 samples are selected to calculate the permeability loss rate separately in the laboratory simulation experiment, the results show that the absolute value of loss rate of the mid-high permeability core is higher than that of low permeability core, but the relative permeability loss rate is lower than that of low permeability core, which, namely, means the low-permeability reservoir has stronger stress sensitivity. The stress sensitivity curve in the high permeability reservoirs could be classified into the type model of "gentle", while the stress sensitivity curve in the low permeability reservoir could be concluded as the "first steep then slow " mode. Hence the bottom-hole flowing pressure must be controlled reasonably in order to keep the productivity well.

scholarly journals Emplacement and biodegradation of oil in fractured basement: the ‘coal’ deposit in Moinian gneiss at Castle Leod, Ross-shire

2016 ◽  
Vol 107 (1) ◽  
pp. 23-32 ◽  
Author(s):  
John Parnell ◽  
Mas'ud Baba ◽  
Stephen Bowden
Keyword(s):  
Lower Devonian ◽  
Fluid Pressure ◽  
Low Permeability ◽  
Coal Deposit ◽  
Basin Inversion ◽  
Mineral Phases ◽  
Metamorphic Basement ◽  
Major Fault ◽  
High Fluid ◽  
Transfer Faults

ABSTRACTBitumen veins were formerly mined as ‘coal’ from Moinian metamorphic basement at Castle Leod, Strathpeffer, Ross-shire. The abundance and spatial concentration of hydrocarbons implies generation of a large volume of oil that exerted a fluid pressure great enough to open veins to 1+ m width. Biomarker characteristics, including β-carotane and a high proportion of C28 steranes, correlate the bitumen to Lower Devonian non-marine shales separated from the Moinian basement by a major fault. Bitumen in the Moinian basement has higher diasterane/sterane ratios than bitumen in the Devonian sequence, indicating greater levels of biodegradation, which may reflect more interaction with water in the basement. Replacive bitumen nodules in the Moinian basement, containing thoriferous/uraniferous mineral phases, are comparable with bitumen nodules in basement terrains elsewhere. Formation of the nodules represents hydrocarbon penetration of low-permeability basement, consistent with high fluid pressure. Bitumen veins are particularly orientated E–W, and may be associated with E–W transfer faults attributed to Permo-Carboniferous basin inversion.

Advance Water-Flooding to Reduce the Stress Sensitivity Affect on Low Permeability Reservoir Development

2011 ◽  
Vol 361-363 ◽  
pp. 520-525
Author(s):  
Jun Feng Yang ◽  
Han Qiao Jiang ◽  
Han Dong Rui ◽  
Xiao Qing Xie
Keyword(s):  
Physical Simulation ◽  
Physical Property ◽  
Stress Sensitivity ◽  
Water Flooding ◽  
Low Permeability ◽  
Formation Pressure ◽  
Exponential Relationship ◽  
Low Permeability Reservoir ◽  
Reservoir Development ◽  
Water Cut

Physical simulation experiments were made to research on the stress sensitivity on physical property of low permeability reservoir rocks. The experimental results shown that effective pressure had good exponential relationship with reservoir permeability. Combining with materaial balance method, reservoir engineering and rational deducation was made to reserach on water-flooding timing of low permeability reservoir development. Several production targets were obtained by these method, such as formation pressure, water and oil production, water cut and so on. The results shown that advanced water-flooding was very important in low permeability reservoir development to reduce the bad impact of stress sensitivity on formation permeability and maintain formation pressure.

Mechanical Properties of Kevlar® KM2 Single Fiber

2005 ◽  
Vol 127 (2) ◽  
pp. 197-203 ◽  
Author(s):  
Ming Cheng ◽  
Weinong Chen ◽  
Tusit Weerasooriya
Keyword(s):  
Isotropic Material ◽  
Axial Stress ◽  
Axial Loading ◽  
Strain Range ◽  
Transversely Isotropic ◽  
Axial Direction ◽  
Strain Response ◽  
Transversely Isotropic Material ◽  
Stress Strain ◽  
Strain Behavior

Kevlar® KM2 fiber is a transversely isotropic material. Its tensile stress-strain response in the axial direction is linear and elastic until failure. However, the overall deformation in the transverse directions is nonlinear and nonelastic, although it can be treated linearly and elastically in infinitesimal strain range. For a linear, elastic, and transversely isotropic material, five material constants are needed to describe its stress-strain response. In this paper, stress-strain behavior obtained from experiments on a single Kevlar KM2 fiber are presented and discussed. The effects of loading rate and the influence of axial loading on transverse and transverse loading on axial stress-strain responses are also discussed.

A Novel Model for Well Production Performance Estimate in Low-Permeability and Tight Reservoirs Considering Stress Sensitivity

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Mingda Dong ◽  
Xuedong Shi ◽  
Jie bai ◽  
Zhilong Yang ◽  
Zhilin Qi
Keyword(s):  
Pressure Gradient ◽  
Effective Stress ◽  
Stress Sensitivity ◽  
Production Performance ◽  
Low Permeability ◽  
Threshold Pressure ◽  
Threshold Pressure Gradient ◽  
Vertical Well ◽  
Tight Reservoirs ◽  
Rock Compressibility

Abstract Stress sensitivity phenomenon is an important property in low-permeability and tight reservoirs and has a large impact on the productivity of production wells, which is defined as the effect of effective stress on the reservoir parameters such as permeability, threshold pressure gradient, and rock compressibility change accordingly. Most of the previous works are focused on the effect of effective stress on permeability and threshold pressure gradient, while rock compressibility is critical of stress sensitivity but rarely noticed. A series of rock compressibility measurement experiments have been conducted, and the quantitative relationship between effective stress and rock compressibility is accurately described in this paper. In the experiment, the defects in previous experiments were eliminated by using a new-type core holder. The results show that as the effective stress increases, the rock compressibility becomes lower. Then, a stress sensitivity model that considers the effect of effective stress on rock compressibility is established due to the experimental results. The well performance of a vertical well estimated by this model shows when considering the effect of effective stress on the rock compressibility, the production rate and recovery factor are larger than those without considering it. Moreover, the effect of porosity and confining pressure on the productivity of a vertical well is also studied and discussed in this paper. The results show that the productivity of a vertical well decreases with the increase in overburden pressure, and increases with the increase in the porosity.

Design of a Micro Tensile Testing Structure to Restrain Non-Axial Alignment Errors

2007 ◽  
Author(s):  
Duanqin Zhang ◽  
Jinkui Chu ◽  
Hongyuan Shen
Keyword(s):  
Tensile Test ◽  
Tensile Testing ◽  
Axial Stress ◽  
Vertical Direction ◽  
Axial Loading ◽  
Axial Direction ◽  
Tensile Specimen ◽  
Spring Constant ◽  
Uniaxial Tensile ◽  
Axial Alignment

Accurate mechanical properties measurements in the micro scale are very important for the design and the fail-safe analysis of MEMS. And the tensile test, as one of the micromechanical experimental techniques, has the advantage of uniform stress and strain fields. In this paper, a new tensile testing structure is presented to solve the non-axial alignment problem in microscale tensile test. The testing structure integrates the specimen and the suspended spring beams on a chip. The function of the additional spring beams is to balance the non-axial loading component and so the specimen is uniaxial tensile. As the spring constant of the tensile specimen in the axial direction is much smaller than the spring constant of the testing structure in the vertical direction, the spring beams could specimen caused by non-axial force. Meanwhile, the spring constant of the specimen in axial direction is much larger than that of the spring beams in the same direction so that the loading shared in the spring beams can be ignored. The performance of the tensile testing structure is confirmed by FE simulations. When the loading force has 2° angle with the axial direction, the stress distribution of the specimen is almost identical with that of under axial loading. The axial stress of the specimen is considerably uniform. That is to say the specimen is uniaxially tensile, although the loading direction is offset the axial. And the force shared in the suspended spring beams is below 3.2% of the loading force. The tensile testing structure could greatly weaken the errors caused by disalignment, and would have big potential to be used in the microscale tensile test.

Elastic Follow-Up Factor for Cruciform Plate Under Bi-Axial Loading

2011 ◽  
Author(s):  
Kuk-Hee Lee ◽  
Yun-Jae Kim ◽  
Robert A. Ainsworth ◽  
David Dean ◽  
Tae-Eun Jin
Keyword(s):  
Finite Element ◽  
Power Law ◽  
Analytical Solutions ◽  
Axial Stress ◽  
Axial Loading ◽  
Finite Element Analyses ◽  
Structural Discontinuity ◽  
Stress States ◽  
Power Law Creep

This paper derives analytical solutions of the elastic follow-up factor for power-law creeping cruciform plates under bi-axial displacements to investigate the effect of multi-axial stress states on elastic follow-up behaviors. Validity of the proposed solutions is checked against the results from finite element analyses using power-law creep material. Based on proposed solutions, effects of the biaxiality, geometry, Poisson’s ratio and creep exponent on elastic follow-up factors are discussed. Present results show that the elastic follow-up factor for structure with structural discontinuity can be significantly affected by the multi-axial stress states.

Dynamic Thermo-Mechanical Properties of Shape Memory Alloy Nanowires Upon Multi-Axial Loading

2011 ◽  
Author(s):  
Rakesh P. Dhote ◽  
Roderick V. N. Melnik ◽  
Jean W. Zu
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Axial Stress ◽  
Phase Field Model ◽  
Axial Loading ◽  
Ginzburg Landau ◽  
Bending Load ◽  
Loading Case

In this paper, we study the behavior of shape memory alloy (SMA) nanowires subjected to multi-axial loading. We use the model developed in our earlier work to study the microstructure and mechanical properties of finite length nanowires. The phase field model with the Ginzburg-Landau free energy is used to model the phase transformation based on the chosen order parameter. The governing equations of the thermo-mechanical model are solved simultaneously for different loading cases. We observe that nanowire behaves in a stiff manner to axial load with complete conversion of the unfavorable martensite to the favorable one. The bending load aids the phase transformation by redistributing the martensitic variants based on the local axial stress sign. The nanowire behavior to multi-axial (axial and bending together) is stiffer axially than the axial loading case. The understanding of the behavior of nanowire to multi-axial loading will be useful in developing better SMA-based MEMS and NEMS devices.

Effect of Gas/Oil Capillary Pressure on Minimum Miscibility Pressure for Tight Reservoirs

SPE Journal ◽  
2019 ◽  
Vol 25 (02) ◽  
pp. 820-831 ◽  
Author(s):  
Kaiyi Zhang ◽  
Bahareh Nojabaei ◽  
Kaveh Ahmadi ◽  
Russell T. Johns
Keyword(s):  
Capillary Pressure ◽  
Hyperbolic Equations ◽  
Fluid Pressure ◽  
Gas Oil ◽  
Minimum Miscibility Pressure ◽  
Tight Reservoir ◽  
Tie Lines ◽  
Tight Reservoirs ◽  
Shale Reservoirs ◽  
The Impact

Summary Shale and tight reservoir rocks have pore throats on the order of nanometers, and, subsequently, a large capillary pressure. When the permeability is ultralow (k < 200 nd), as in many shale reservoirs, diffusion might dominate over advection, so that the gas injection might no longer be controlled by the multicontact minimum miscibility pressure (MMP). For gasfloods in tight reservoirs, where k > 200 nd and capillary pressure is still large, however, advection likely dominates over diffusive transport, so that the MMP once again becomes important. This paper focuses on the latter case to demonstrate that the capillary pressure, which has an impact on the fluid pressure/volume/temperature (PVT) behavior, can also alter the MMP. The results show that the calculation of the MMP for reservoirs with nanopores is affected by the gas/oil capillary pressure, owing to alteration of the key tie lines in the displacement; however, the change in the MMP is not significant. The MMP is calculated using three methods: the method of characteristics (MOC); multiple mixing cells; and slimtube simulations. The MOC method relies on solving hyperbolic equations, so the gas/oil capillary pressure is assumed to be constant along all tie lines (saturation variations are not accounted for). Thus, the MOC method is not accurate away from the MMP but becomes accurate as the MMP is approached when one of the key tie lines first intersects a critical point (where the capillary pressure then becomes zero, making saturation variations immaterial there). Even though the capillary pressure is zero for this key tie line, its phase compositions (and, hence, the MMP) are impacted by the alteration of all other key tie lines in the composition space by the gas/oil capillary pressure. The reason for the change in the MMP is illustrated graphically for quaternary systems, in which the MMP values from the three methods agree well. The 1D simulations (typically slimtube simulations) show an agreement with these calculations as well. We also demonstrate the impact of capillary pressure on CO2-MMP for real reservoir fluids. The effect of large gas/oil capillary pressure on the characteristics of immiscible displacements, which occur at pressures well below the MMP, is discussed.

scholarly journals Applicability Analysis of Klinkenberg Slip Theory in the Measurement of Tight Core Permeability

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2351 ◽  
Author(s):  
Jirui Zou ◽  
Xiangan Yue ◽  
Weiqing An ◽  
Jun Gu ◽  
Liqi Wang
Keyword(s):  
High Pressure ◽  
Gas Permeability ◽  
Fluid Dynamic ◽  
Dynamic Parameter ◽  
Low Pressure ◽  
Low Permeability ◽  
Apparent Permeability ◽  
Tight Reservoir ◽  
Gas Seepage ◽  
The Relationship

The Klinkenberg slippage theory has widely been used to obtain gas permeability in low-permeability porous media. However, recent research shows that there is a deviation from the Klinkenberg slippage theory for tight reservoir cores under low-pressure conditions. In this research, a new experimental device was designed to carry out the steady-state gas permeability test with high pressure and low flowrate. The results show that, unlike regular low-permeability cores, the permeability of tight cores is not a constant value, but a variate related to a fluid-dynamic parameter (flowrate). Under high-pressure conditions, the relationship between flowrate and apparent permeability of cores with low permeability is consistent with Klinkenberg slippage theory, while the relationship between flowrate and apparent permeability of tight cores is contrary to Klinkenberg slip theory. The apparent permeability of tight core increases with increasing flowrate under high-pressure conditions, and it is significantly lower than the Klinkenberg permeability predicted by Klinkenberg slippage theory. The difference gets larger when the flowrate becomes lower (back pressure increases and pressure difference decreases). Therefore, the Klinkenberg permeability which is obtained by the Klinkenberg slippage theory by using low-pressure experimental data will cause significant overestimation of the actual gas seepage capacity in the tight reservoir. In order to evaluate the gas seepage capacity in a tight reservoir precisely, it is necessary to test the permeability of the tight cores directly at high pressure and low flowrate.

Sign in / Sign up

Export Citation Format

Share Document