A Novel Method To Assess Stimulation of Sandstone Cores Damaged by Fines Migration

SPE Journal ◽  
2021 ◽  
pp. 1-23
Author(s):  
Ahmed Hanafy ◽  
Hisham A. Nasr-El-Din ◽  
Zoya Heidari
Keyword(s):  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Deionized Water ◽  
Formation Damage ◽  
Fines Migration ◽  
The Core ◽  
Well Stimulation ◽  
Stimulation Of

Summary Sandstone stimulation remains challenging because of formation heterogeneity and the sensitivity of clay minerals to acids such as hydrochloric acid (HCl) and mud acid [HCL/hydrofluoric acid (HF)]. Fines migration complicates the well-stimulation process and reduces formation productivity. Multiple field studies show that some stimulation methods can result in permanent damage to the rock matrix near the wellbore because of fines migration. This study aims to locate, quantify, and describe the damage resulting from fines migration after the stimulation of sandstone formations, and examine the composition of clay content in the formation and its effects on the stimulation process and subsequent fines migration. This work evaluates the fines-migration damage during well stimulation in Bandera, Gray Berea, and Kentucky Sandstones. Fines migration was induced by injecting deionized water between brine stages to trigger the mobilization of the clay minerals in sample cores. HCl, formic acid (HCOOH), and HF stimulation stages were then injected after the fines-migration induction. The new formation-damage-evaluation method proposed in this work uses computed-tomography (CT) scanning and nuclear-magnetic-resonance (NMR) measurements before and after the fines-migration induction and experimental stimulation. The CT and NMR data were then combined and processed to generate a 3D representation of the pore structure throughout the core samples, which yields insight on how the clay composition affects the stimulation process and changes the pore system. The developed technique exhibited an excellent ability to visualize the pore-size distribution and the changes in the pore structure after the fines-migration damage and the acid treatment. The mapping of the pore-size distribution using CT and its comparison with the rock mineralogy of Bandera, Gray Berea, and Kentucky Sandstones successfully predicted the changes in the pore structure of these formations upon induction of fines-migration damage using deionized water. These changes in pore structure prevailed as a controlling variable of the acidizing process. The stimulation of the damaged cores at 150 and 250°F resulted in aluminosilicate deposition toward the core outlet. These deposits are attributed to the acid leaching of aluminum (Al) and iron (Fe) ions from the aluminosilicate structures. The higher temperature resulted in the deposition of aluminosilicates closer to the injection point. However, an enhancement in permeability was noticed in all of the sampled formations, which was because of the propagation of narrow channels between heavily deformed pore structures. This work adds to the understanding of sandstone-stimulation technology and contributes a new process to assess the effects of acid stimulation on fines-migration damage. The high level of resolution in visualizing the changes in the pore structure facilitates the optimization of treatments to reduce costs while improving production from clay-rich sandstone formations. This technique offers further potential as a formation-evaluation tool for real-time assessment of a variety of formation-damage mechanisms, such as fracturing fluids and water blockage.

scholarly journals Construction of pore structure and lithology of digital rock physics based on laboratory experiments

2021 ◽  
Vol 11 (5) ◽  
pp. 2113-2125
Author(s):  
Chenzhi Huang ◽  
Xingde Zhang ◽  
Shuang Liu ◽  
Nianyin Li ◽  
Jia Kang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Laboratory Experiments ◽  
Rock Physics ◽  
Reconstruction Method ◽  
Digital Rock Physics ◽  
Digital Rock ◽  
The Core

AbstractThe development and stimulation of oil and gas fields are inseparable from the experimental analysis of reservoir rocks. Large number of experiments, poor reservoir properties and thin reservoir thickness will lead to insufficient number of cores, which restricts the experimental evaluation effect of cores. Digital rock physics (DRP) can solve these problems well. This paper presents a rapid, simple, and practical method to establish the pore structure and lithology of DRP based on laboratory experiments. First, a core is scanned by computed tomography (CT) scanning technology, and filtering back-projection reconstruction method is used to test the core visualization. Subsequently, three-dimensional median filtering technology is used to eliminate noise signals after scanning, and the maximum interclass variance method is used to segment the rock skeleton and pore. Based on X-ray diffraction technology, the distribution of minerals in the rock core is studied by combining the processed CT scan data. The core pore size distribution is analyzed by the mercury intrusion method, and the core pore size distribution with spatial correlation is constructed by the kriging interpolation method. Based on the analysis of the core particle-size distribution by the screening method, the shape of the rock particle is assumed to be a more practical irregular polyhedron; considering this shape and the mineral distribution, the DRP pore structure and lithology are finally established. The DRP porosity calculated by MATLAB software is 32.4%, and the core porosity measured in a nuclear magnetic resonance experiment is 29.9%; thus, the accuracy of the model is validated. Further, the method of simulating the process of physical and chemical changes by using the digital core is proposed for further study.

Magnetic-Resonance Imaging of Fines Migration in Berea Sandstone

SPE Journal ◽  
2017 ◽  
Vol 22 (05) ◽  
pp. 1385-1392 ◽  
Author(s):  
Armin Afrough ◽  
Mohammad Sadegh Zamiri ◽  
Laura Romero-Zerón ◽  
Bruce J. Balcom
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Aqueous Phase ◽  
Resonance Imaging ◽  
Fines Migration ◽  
Clay Particles ◽  
The Core

Summary Fines migration is a phenomenon of practical importance in the petroleum-production and drilling industry. The movement of clay particles, induced by incompatible aqueous-phase chemistry or high flow rate, obstructs pore throats downstream of the fluid flow, leading to permeability reductions that can be as large as two orders of magnitude. Magnetic-resonance-imaging (MRI) methods derived from the Carr-Purcell-Meiboom-Gill (CPMG) method (Meiboom and Gill 1958) can map T2 distributions in porous rocks, hence showing the spatial variation of the pseudo-pore-size distribution. In this work, the traditional water-shock experiment was used to mobilize clay particles in the aqueous phase flowing in Berea core plugs. Spin-echo single-point imaging (SE-SPI), a phase-encoding MRI method derived from the CPMG method, was used to determine spatially resolved T2 spectra of the samples, and therefore the pseudo-pore-size distributions. The shift in the T2 spectra of the core inlet and outlet showed opposite trends. The pore-size distribution of the inlet and outlet, inferred from T2 distributions, were shifted to larger and smaller values, respectively. Therefore, the average pore size was increased at the inlet of the core and reduced at the outlet of the core. This MRI method provides a new analytical approach to screen reservoirs for potential fines-migration problems.

scholarly journals Experimental investigation on pore size distribution and drying kinetics during lyophilization of sugar solutions

2018 ◽  
Author(s):  
Petra Foerst ◽  
M. Lechner ◽  
N. Vorhauer ◽  
H. Schuchmann ◽  
E. Tsotsas
Keyword(s):  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Freeze Drying ◽  
Three Dimensional ◽  
Drying Kinetics ◽  
Process Efficiency ◽  
Freeze Dried ◽  
Pore Size Distributions

The pore structure is a decisive factor for the process efficiency and product quality of freeze dried products. In this work the two-dimensional ice crystal structure was investigated for maltodextrin solutions with different concentrations by a freeze drying microscope. The resulting drying kinetics was investigated for different pore structures. Additionally the three-dimensional pore structure of the freeze dried samples was measured by µ-computed tomography and the pore size distribution was quantified by image analysis techniques. The two- and three-dimensional pore size distributions were compared and linked to the drying kinetics.Keywords: pore size distribution; freeze drying; maltodextrin solution; freeze drying microscope   

scholarly journals Ink-bottle Effect and Pore Size Distribution of Cementitious Materials Identified by Pressurization–Depressurization Cycling Mercury Intrusion Porosimetry

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1454 ◽  
Author(s):  
Yong Zhang ◽  
Bin Yang ◽  
Zhengxian Yang ◽  
Guang Ye
Keyword(s):  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Mercury Intrusion Porosimetry ◽  
Cementitious Materials ◽  
Limestone Powder ◽  
Accurate Estimation ◽  
Mercury Intrusion ◽  
Pore Size Distributions

Capturing the long-term performance of concrete must be underpinned by a detailed understanding of the pore structure. Mercury intrusion porosimetry (MIP) is a widely used technique for pore structure characterization. However, it has been proven inappropriate to measure the pore size distribution of cementitious materials due to the ink-bottle effect. MIP with cyclic pressurization–depressurization can overcome the ink-bottle effect and enables a distinction between large (ink-bottle) pores and small (throat) pores. In this paper, pressurization–depressurization cycling mercury intrusion porosimetry (PDC-MIP) is adopted to characterize the pore structure in a range of cementitious pastes cured from 28 to 370 days. The results indicate that PDC-MIP provides a more accurate estimation of the pore size distribution in cementitious pastes than the standard MIP. Bimodal pore size distributions can be obtained by performing PDC-MIP measurements on cementitious pastes, regardless of the age. Water–binder ratio, fly ash and limestone powder have considerable influences on the formation of capillary pores ranging from 0.01 to 0.5 µm.

scholarly journals Comprehensive characterization of nano-pore system for Chang 7 shale oil reservoir in Ordos Basin

2020 ◽  
pp. 014459872097067
Author(s):  
Hui Gao ◽  
Jie Cao ◽  
Chen Wang ◽  
Teng Li ◽  
Mengqing He ◽  
...  
Keyword(s):  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Ordos Basin ◽  
Oil Reservoir ◽  
Shale Oil ◽  
Size Distributions ◽  
Group I ◽  
Group Ii

Detailed study on the pore structure of shale oil reservoir is significantly for the exploration and development, and the conventional single pore structure measurement method cannot accurately describe the pore structure characteristics of the shale oil reservoir. In this paper, the Field Emission Scanning Electron Microscope (FESEM), low-pressure nitrogen adsorption (LP-N2A) and mercury injection porosimetry (MIP) techniques are used to comprehensive evaluate the pore structure of Chang 7 shale oil reservoir. The FESEM results show that inter pores, inner pores, organic pores and micro-cracks are developed in Chang 7 shale oil reservoir, and the pore structure can be divided into two groups from the LP-N2A and MIP. A new pore structure comprehensive evaluation method was promoted according to the connection points from the pore sizes distribution curves of LP-N2A and MIP. With this comprehensive analysis of the pore size distribution, the pore size distribution of various shale samples feature as triple-peak pattern. Due to the heterogeneity of the shale oil samples, the corresponding pore apertures of the connection points are various, and the overall pore size distribution of shale oil reservoir samples can also be divided into two types. In Group I, the size distributions exhibited a bimodal feature in a narrow range from 1.71 to 100 nm. The trimodal feature of size distributions was captured in Group II with the pore diameter ranges from 1.71 to 1426.8 nm. Group I features smaller sorting coefficient and good pore connectivity. However, the trimodal corresponds to the complex pore structure and larger sorting coefficient for Group II.

Mechanical Properties and Pore Size Distribution in Athermal Porous Glasses

Soft Matter ◽  
2021 ◽  
Author(s):  
Sucharita Niyogi ◽  
Bhaskar Sen Gupta
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Porous Glass ◽  
Three Dimensional ◽  
Dynamics Model ◽  
Porous Glasses

In this paper, we study the mechanical properties and pore structure in a three-dimensional molecular dynamics model of porous glass under athermal quasistatic shear. The vitreous samples are prepared by...

scholarly journals In-Situ Pore Structure Analysis During Aging and Drying of Gels

1990 ◽  
Vol 180 ◽  
Author(s):  
Douglas M. Smith ◽  
Pamela J. Davis ◽  
C. Jeffrey Brinker
Keyword(s):  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Pore Fluid ◽  
Structure Evolution ◽  
High Ph ◽  
Drying Rates

ABSTRACTThe use of NMR relaxation measurements for the in-situ study of pore structure evolution during gel aging and drying is illustrated. The change in the pore size distribution and surface area of both wet and dried gels is examined as a function of aging conditions including temporal aging, thermal aging, changing pH, and changing pore fluid. The effect of pore fluid pH on dissolution/reprecipitation in ordered packings of monodisperse silica spheres is also examined as a model system for particulate gels. As expected, the pore size distribution narrows with increasing time of treatment in high pH pore fluids. Interpretation of high pH results for the wet state is complicated by a microporous layer which forms on colloidal silica resulting in significantly larger wet surface area as compared to the final dried material. Narrowing of the pore size distribution, which is of interest for maximizing drying rates, is maximized in the least time by using either high pH or repeated ethanol washes for the base-catalyzed gel (B2) used.

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