A rock core wettability index using NMR T measurements

Al-Garadi, Karem; El-Husseiny, Ammar; Elsayed, Mahmoud; Connolly, Paul R. J.; Mahmoud, Mohamed; Johns, Michael L.; Adebayo, Abdulrauf R.

doi:10.1016/j.petrol.2021.109386

Cited by 28 publications

(17 citation statements)

References 49 publications

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“…Similarly, much shorter T 2,mean values were observed for the samples aged with 10 wt % (Figure b), 5 wt % (Figure c), and 1 wt % HCl (Figure d) (35, 58, and 78 ms, respectively), compare Figure . Here, the T 2 values have aligned far from that of bulk brine (1260 ms), indicating that surface relaxation strongly contributed toward achieving much shorter relaxation times for higher acid concentrations ( T 2 , 15% wt HCl < T 2 , 10% wt HCl < T 2 , 5% wt HCl < T 2 , 1% wt HCl ≪< T 2 , bulk ) …”

Section: Resultsmentioning

confidence: 85%

“…Studies have suggested that NMR detects three different modes of relaxations, namely, bulk relaxation, surface relaxation, and the relaxation instigated by molecular diffusion in a gradient field . Therefore, the T 2 response time is expressed as a function of these three elements as follows ,, Here, T 2 refers to the overall relaxation time, T 2,surface is the surface relaxation time, T 2,bulk is the bulk relaxation time, and T 2,diffusion is the molecular diffusion relaxation.…”

Section: Resultsmentioning

confidence: 99%

“…Here, bulk relaxation is an inherent property of the fluid caused by molecular movement and molecular interactions, whereas in surface relaxation, a magnetized molecule is demagnetized by the solid rock surface. , T 2,diffusion is minimal and can be neglected since the background magnetic field gradients which arise due to the susceptibility differences between the fluid and the rock matrix are minimal. − Therefore, surface and bulk relaxations are considered to be the dominant modes of relaxations; the measured relaxation spectrum is a combination of these two parameters …”

Section: Resultsmentioning

confidence: 99%

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Effect of Inorganic Acid Concentration on Sandstone Surface Chemistry Examined via Nuclear Magnetic Resonance

et al. 2022

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Despite rock surface charge being a critical component in predicting the reservoir behavior, the subsurface characteristics are still poorly understood, specially, those of sandstones, which are of key economic importance in the oil and gas industry. Even though a rock surface is originally considered to be neutrally charged, surface charges are created in the presence of water and dissolved ions. Moreover, a major proportion of sandstone reservoirs are composed of silica which creates surface charges through dissociation of silanols in the presence of water and/or acids. Rock subsurface chemistry is a primary factor that determines the variability of several key reservoir parameters (e.g., capillary pressures or residual saturations). Nuclear magnetic resonance (NMR) is a well-established tool with which such rock surface chemistry can be measured in situ. For example, surface charge is a vital characteristic with which single-phase and multiphase fluid flow behavior can be predicted (e.g., it determines colloidal stabilities or streaming potentials); the surface charge/surface potential is thus highly significant for a wide range of applications and processes, for example, enhanced oil/gas recovery, hydrogen/CO 2 geo-storage, or contaminant transport. This study provides novel insights into fundamental rock surface chemistry and how this is influenced by the acidity of the aqueous phase in the subsurface. Specifically, we systematically examined sandstone surface chemistry as a function of mineral acid concentration via NMR T 2 response measurements. For this, Bentheimer sandstone samples were treated with aqueous hydrochloric acid solutions of different concentrations, and NMR T 2 distribution measurements were performed for the initial and treated samples. The results indicated that higher concentrations of hydrochloric acid (and thus more surface protonation) yielded much shorter T 2 relaxation times compared to lower concentrations. This work thus provides fundamental information about in situ sandstone surface chemistry and therefore aids in the basic understanding and implementation of key geologic questions and engineering projects.

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Section: Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Effect of Inorganic Acid Concentration on Sandstone Surface Chemistry Examined via Nuclear Magnetic Resonance

et al. 2022

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“…NMR petrophysical core analysis is a non-invasive, powerful, and reliable tool for the routine core analysis (RCA) as it provides accurate determination for porosity, pore size distribution, fluids saturation, and permeability (Arnold et al 2006;Elsayed et al 2021a;Freedman et al 2001;Howard and Kenyon 1992;Mitchell et al 2015;Mitchell and Fordham 2014). Moreover, special core analysis (SCA) experiments such as wettability, capillary pressure, and clay minerals analysis can be determined using NMR (Al-Garadi et al 2022;Connolly et al 2017;Elsayed et al 2020a;Freedman et al, 2003a;Newgord et al 2020;Tandon et al 2020;Tandon and Heidari 2018;Worden and Morad 1999). Numerous EOR methods including acid and fracture stimulation, thermochemical fluids for gas condensate removal, miscible gas injection (huff 'n' puff), CO 2 injection, and thermal-EOR have been evaluated with the use of different NMR measurements (Adebayo et al 2020a, b;Chen et al 2018a, b;Dang et al 2019;Elsayed et al 2021bElsayed et al , 2020bHassan et al 2020;Mukhametdinova et al 2020).…”

Section: Introductionmentioning

confidence: 99%

“…water and oil saturations, respectively The introduced NMR index was tested for carbonated samples of AH wettability values ranging from − 0.6 to 0.5 Needs more input parametersAl-Garadi et al, (2022) …”

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confidence: 99%

A review on the applications of nuclear magnetic resonance (NMR) in the oil and gas industry: laboratory and field-scale measurements

Elsayed

Isah

Hiba

et al. 2022

J Petrol Explor Prod Technol

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This review presents the latest update, applications, techniques of the NMR tools in both laboratory and field scales in the oil and gas upstream industry. The applications of NMR in the laboratory scale were thoroughly reviewed and summarized such as porosity, pores size distribution, permeability, saturations, capillary pressure, and wettability. NMR is an emerging tool to evaluate the improved oil recovery techniques, and it was found to be better than the current techniques used for screening, evaluation, and assessment. For example, NMR can define the recovery of oil/gas from the different pore systems in the rocks compared to other macroscopic techniques that only assess the bulk recovery. This manuscript included different applications for the NMR in enhanced oil recovery research. Also, NMR can be used to evaluate the damage potential of drilling, completion, and production fluids laboratory and field scales. Currently, NMR is used to evaluate the emulsion droplet size and its behavior in the pore space in different applications such as enhanced oil recovery, drilling, completion, etc. NMR tools in the laboratory and field scales can be used to assess the unconventional gas resources and NMR showed a very good potential for exploration and production advancement in unconventional gas fields compared to other tools. Field applications of NMR during exploration and drilling such as logging while drilling, geosteering, etc., were reviewed as well. Finally, the future and potential research directions of NMR tools were introduced which include the application of multi-dimensional NMR and the enhancement of the signal-to-noise ratio of the collected data during the logging while drilling operations.

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Quantifying acid diversion efficiency through NMR tortuosity measurements

Elsayed

BinGhanim

Aljawad

et al. 2022

J Petrol Explor Prod Technol

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The diversion efficiency measures the acid capacity to change its flow direction to the lower permeability reservoir sections. A good acid diverter creates a tortuous (zigzagged) wormhole within the acidized core sample in a laboratory setup. Here, we studied two different acid diverters compared to the conventional hydrochloric acid (HCl) to investigate their efficiency in changing the wormhole direction inside the rock core. Nuclear magnetic resonance (NMR) can be used to measure the 3D tortuosity of a rock sample; hence, we propose it as a tool to measure acid diversion efficiency because it can be applied in the field and in the laboratory. Two acid systems were utilized: straight 15 wt.% HCl acid and gelled acid consisting of 15 wt.% HCl acid and polyacrylamide polymer (PAM). Four coreflooding experiments were conducted on 1.5 inch-diameter × 3 inch-length Indiana limestone samples, two with straight HCl acid and two with gelled HCl acid at different PAM concentrations. NMR was utilized to measure the T2 distribution of the rock samples and diffusion tortuosity in two orthogonal directions. Also, X-ray computed tomography (CT) of the acidized samples was taken to visualize the wormholes. Results showed that the polymer-based acid-created zigzagged paths, and more acid volume was consumed to create the wormholes using CT. NMR diffusion tortuosity measurements showed that the tortuosity was reduced along the wormhole direction in all experiments. Nevertheless, the gelled acid treatments showed a significant reduction of the tortuosity orthogonal to the main wormhole path. The diversion efficiency of the 50 lbm/ 1000 gal PAM-gelled acid was 35% higher compared to the straight HCl acid. On the contrary, the 30 lbm/ 1000 gal PAM-gelled acid gave only 10% improvement in the diversion. The index could screen quantitatively which diverting acid is more efficient. We introduced a new diversion index based on the NMR diffusion measurements in this study to quantify the diversion capacity of an acid system in carbonate rock.

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A rock core wettability index using NMR T measurements

Cited by 28 publications

References 49 publications

Effect of Inorganic Acid Concentration on Sandstone Surface Chemistry Examined via Nuclear Magnetic Resonance

Effect of Inorganic Acid Concentration on Sandstone Surface Chemistry Examined via Nuclear Magnetic Resonance

A review on the applications of nuclear magnetic resonance (NMR) in the oil and gas industry: laboratory and field-scale measurements

Quantifying acid diversion efficiency through NMR tortuosity measurements

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