Modelling stress-induced permeability alterations in sandstones using CT scan-based representations of the pore space morphology

2022 ◽  
Vol 150 ◽  
pp. 104998
Author(s):  
Karim Ehab Moustafa Kamel ◽  
Pierre Gerard ◽  
Jean-Baptiste Colliat ◽  
Thierry J. Massart
Keyword(s):  
Ct Scan ◽  
Pore Space ◽  
Permeability Alterations

Numerical modelling based saturation conductivity estimation uncertainty – influence of the quality of the pore space geometry representation based on X-ray CT images

2020 ◽  
Author(s):  
Krzysztof Lamorski ◽  
Bartłomiej Gackiewicz ◽  
Cezary Sławiński ◽  
Shao-Yiu Hsu ◽  
Liang-Cheng Chang
Keyword(s):  
Ct Scan ◽  
Cell Size ◽  
Stokes Equations ◽  
Pore Space ◽  
Ct Scanning ◽  
Ct Images ◽  
X Ray ◽  
Space Geometry ◽  
The Impact ◽  
Mesh Cell

<p>X-ray computational tomography (CT) is becoming more and more popular research tool in geosciences. Estimation of the saturated conductivity of the porous media based on X-ray CT images is an example of its application. In case of simulations for the pore media, which are approximated by the very complicated meshes, problems might arise when mesh does not follow the shape of pore-space ideally, which may happen due to limitations imposed (e.g. due to some technical constraints) on minimum mesh cell size which usually is bigger than CT scan resolution used for determination of the pore space. If this is the case, the mesh can’t be generated properly in the narrow regions of the pore-space.</p><p>The work tries to quantify the impact of the limited mesh quality on estimation of the saturated conductivity coefficient. Four mesh generation parameters, resulting in different sizes of the minimum mesh cell size, were compared. For comparison five different pore media (three sandpacks prepared from different sand fractions and two types of sandstones) were used, all of them were used in two repetitions which resulted in 10 studied samples in total. First samples were X-ray CT scanned with resolution 2um. Than images were thresholded to obtain information about pore-space. In the next step, for all of 10 3D images of pore-space, mesh was generated in four repetitions differing with minimum mesh cell size: 2.56, 3.41, 5.12 and 10.25 times greater than voxel size used for CT scanning.</p><p>Saturated conductivity was simulated based on prepared meshes using finite volume based solver of the Navier-Stokes equations. Estimated for each sample saturated conductivity differed from 12% for coarse media to 200% for fine grain media for different numerical meshes representing with different accuracy pore space geometry.</p><p>Based on samples studied, one may conclude that for optimal results of saturated conductivity numerical estimation, the smallest numerical mesh’s cell size should be of the level of pore media CT scan resolution.  </p><p> </p><p>Acknowledgments:</p><p>This work was partially supported by a grant from the Polish National Centre for Research and Development within the contract no.: PL-TW/IV/5/2017.</p>

Correlation of Pore Structure and Permeability by SEM-Image Analysis

1990 ◽  
Vol 48 (1) ◽  
pp. 428-429
Author(s):  
C. A. Callender ◽  
Wm. C. Dawson ◽  
J. J. Funk
Keyword(s):  
Image Analysis ◽  
Pore Structure ◽  
Imaging System ◽  
Pore Space ◽  
Simulation Models ◽  
Image Analyzer ◽  
Imaging Data ◽  
Sem Images ◽  
Thin Sections ◽  
Rock Types

The geometric structure of pore space in some carbonate rocks can be correlated with petrophysical measurements by quantitatively analyzing binaries generated from SEM images. Reservoirs with similar porosities can have markedly different permeabilities. Image analysis identifies which characteristics of a rock are responsible for the permeability differences. Imaging data can explain unusual fluid flow patterns which, in turn, can improve production simulation models.Analytical SchemeOur sample suite consists of 30 Middle East carbonates having porosities ranging from 21 to 28% and permeabilities from 92 to 2153 md. Engineering tests reveal the lack of a consistent (predictable) relationship between porosity and permeability (Fig. 1). Finely polished thin sections were studied petrographically to determine rock texture. The studied thin sections represent four petrographically distinct carbonate rock types ranging from compacted, poorly-sorted, dolomitized, intraclastic grainstones to well-sorted, foraminiferal,ooid, peloidal grainstones. The samples were analyzed for pore structure by a Tracor Northern 5500 IPP 5B/80 image analyzer and a 80386 microprocessor-based imaging system. Between 30 and 50 SEM-generated backscattered electron images (frames) were collected per thin section. Binaries were created from the gray level that represents the pore space. Calculated values were averaged and the data analyzed to determine which geological pore structure characteristics actually affect permeability.

1596: Lymph Node Staging in Prostate Cancer by the use of 11C-CHOLIN-PET/CT Scan Imaging

2005 ◽  
Vol 173 (4S) ◽  
pp. 432-432
Author(s):  
Georg C. Bartsch ◽  
Norbert Blumstein ◽  
Ludwig J. Rinnab ◽  
Richard E. Hautmann ◽  
Peter M. Messer ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Lymph Node ◽  
Ct Scan ◽  
Lymph Node Staging ◽  
Pet Ct ◽  
Pet Ct Scan

Synchronous celiac axis and superior mesenteric artery embolism

VASA ◽  
2011 ◽  
Vol 40 (6) ◽  
pp. 495-498 ◽  
Author(s):  
Rajkovic ◽  
Zelic ◽  
Papes ◽  
Cizmek ◽  
Arslani
Keyword(s):  
Atrial Fibrillation ◽  
Small Intestine ◽  
Abdominal Pain ◽  
Ct Scan ◽  
Superior Mesenteric Artery ◽  
Mesenteric Artery ◽  
Abdominal Cavity ◽  
Celiac Axis ◽  
Contrast Administration ◽  
Artery Embolism

We present a case of combined celiac axis and superior mesenteric artery embolism in a 70-year-old patient that was examined in emergency department for atrial fibrillation and diffuse abdominal pain. Standard abdominal x-ray showed air in the portal vein. CT scan with contrast showed air in the lumen of the stomach and small intestine, bowel distension with wall thickening, and a free gallstone in the abdominal cavity. Massive embolism of both celiac axis and superior mesenteric artery was seen after contrast administration. On laparotomy, complete necrosis of the liver, spleen, stomach and small intestine was found. Gallbladder was gangrenous and perforated, and the gallstone had migrated into the abdominal cavity. We found free air that crackled on palpation of the veins of the gastric surface. The patient’s condition was incurable and she died of multiple organ failure a few hours after surgery. Acute visceral thromboembolism should always be excluded first if a combination of atrial fibrillation and abdominal pain exists. Determining the serum levels of d-dimers and lactate, combined with CT scan with contrast administration can, in most cases, confirm the diagnosis and lead to faster surgical intervention. It is crucial to act early on clinical suspicion and not to wait for the development of hard evidence.

Successful Endovascular Repair of a Leaking Abdominal Aortic Aneurysm under Local Anesthesia

Swiss Surgery ◽  
2001 ◽  
Vol 7 (2) ◽  
pp. 86-89 ◽  
Author(s):  
Lachat ◽  
Pfammatter ◽  
Bernard ◽  
Jaggy ◽  
Vogt ◽  
...  
Keyword(s):  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Ct Scan ◽  
Local Anesthesia ◽  
Endovascular Repair ◽  
Anesthetic Management ◽  
High Risk Patient ◽  
Invasive Technique ◽  
Chronic Obstructive ◽  
Abdominal Aortic

Local anesthesia is a safe and less invasive anesthetic management for the endovascular approach to elective aortic aneurysm. We have successfully extended the indication of local anesthesia to a high-risk patient with leaking aneurysm and stable hemodynamics. Patient and methods: A 86 year old patient with renal insufficiency due to longstanding hypertension, coronary artery and chronic obstructive lung disease was transferred to our hospital with a leaking abdominal aortic aneurysm. Stable hemodynamics allowed to perform a fast CT scan, that confirmed the feasibility of endovascular repair. A bifurcated endograft (24mm x 12mm x 153mm) was implanted under local anesthesia. Results: The procedure was completed within 85 minutes without problems. The complete sealing of the aneurysm was confirmed by CT scan on the third postoperative day. Twenty months later, the patient is doing well and radiological control confirmed complete exclusion of the aneurysm. Discussion: The endoluminal treatment is a minimally invasive technique. It's feasibility can be rapidly assessed by CT scan. The transfemoral implantation can be performed under local anesthesia provided that hemodynamics are stable. This anesthetic management seems to be particularly advantageous for leaking abdominal aortic aneurysm since it doesn't change the hemodynamic situation in contrast to general anesthesia. Hemodynamic instability, abdominal distension or tenderness may indicate intraperitoneal rupture and conversion to open graft repair should be performed without delay.

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