Image-based petrophysical parameters: CT imaging of chalk cuttings and experimental comparisons by plug-size upscaling

TY - JOUR

T1 - Image-based petrophysical parameters

T2 - CT imaging of chalk cuttings and experimental comparisons by plug-size upscaling

AU - Noe-Nygaard, Jakob

AU - Engstrøm, Finn

AU - Sølling, Theis Ivan

AU - Roth, Sven

PY - 2017

Y1 - 2017

N2 - In the present study, the focus is on two 2- to 3-mm cuttings-scale reservoir chalk samples chosen such that the resolution of the pore space is challenging the state of the art and the permeability differs by a factor of four. We compare the petrophysical parameters that are derived from nano-computed-tomography (nano-CT) images of trim sections and cuttings. Moreover, the trim-section results are upscaled to trim size to form the basis of an additional comparison. The results are also benchmarked against conventional core analysis (CCAL) results on trim-size samples. The comparison shows that petrophysical parameters from CT imaging agree reasonably well with those determined experimentally. The upscaled results show some discrepancy with the nano-CT results, particularly in the case of the low-permeability plug. This is probably because of the challenge in finding a representative subvolume. For the cuttings, the differences are significant for the low-permeability plug. For the two-phase-flow data, the predicted relative permeability endpoints differ significantly. The root cause of this again is attributed to the more-complex structure of the pore network in the low-permeability carbonate. The experiment was also run directly from the micro-CT results on a cutting measured on an in-house instrument; the results clearly show that micro-CT measurements on chalk do not capture the pore space with sufficient detail to be predictive. Overall, with the appropriate resolution, the present study shows that it is indeed feasible to obtain petrophysical parameters from imaging experiments on cuttings.

AB - In the present study, the focus is on two 2- to 3-mm cuttings-scale reservoir chalk samples chosen such that the resolution of the pore space is challenging the state of the art and the permeability differs by a factor of four. We compare the petrophysical parameters that are derived from nano-computed-tomography (nano-CT) images of trim sections and cuttings. Moreover, the trim-section results are upscaled to trim size to form the basis of an additional comparison. The results are also benchmarked against conventional core analysis (CCAL) results on trim-size samples. The comparison shows that petrophysical parameters from CT imaging agree reasonably well with those determined experimentally. The upscaled results show some discrepancy with the nano-CT results, particularly in the case of the low-permeability plug. This is probably because of the challenge in finding a representative subvolume. For the cuttings, the differences are significant for the low-permeability plug. For the two-phase-flow data, the predicted relative permeability endpoints differ significantly. The root cause of this again is attributed to the more-complex structure of the pore network in the low-permeability carbonate. The experiment was also run directly from the micro-CT results on a cutting measured on an in-house instrument; the results clearly show that micro-CT measurements on chalk do not capture the pore space with sufficient detail to be predictive. Overall, with the appropriate resolution, the present study shows that it is indeed feasible to obtain petrophysical parameters from imaging experiments on cuttings.

U2 - 10.2118/183634-PA

DO - 10.2118/183634-PA

M3 - Journal article

AN - SCOPUS:85012942121

SN - 1086-055X

VL - 22

SP - 42

EP - 52

JO - SPE Journal

JF - SPE Journal

IS - 1

ER -