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Title: Numerical simulations of depressurization-induced gas production from gas hydrates using 3-D heterogeneous models of L-Pad, Prudhoe Bay Unit, North Slope Alaska

Gas production potential is estimated using a three-dimensional reservoir model based on gas hydrate deposits located in the Prudhoe Bay region of the Alaska's North Slope. The model incorporates two hydrate-bearing sand units using detailed reservoir geological and structural information obtained from past and recent drilling programs. Geostatistical porosity models, conditioned to log data from 78 wells drilled in the vicinity of the Prudhoe Bay “L-Pad,” were developed, providing 3D heterogeneity in porosity, porosity-dependent hydrate saturation, and intrinsic permeability. The simulations utilize both vertical and inclined wellbores to induce depressurization of the reservoir at a constant bottom-hole pressure. The results show the superior performance of the inclined well design. Average gas production rates during the first five years were ~6.0 × 10 4 ST m 3/day (~2.1 MMSCF/day) and ~2.7 × 10 4 ST m 3/day (~1.0 MMSCF/day) for incline and vertical wells, respectively. After 30 years 5.3 × 10 8 - 5.7 × 10 8 ST m 3 (18.6–20.2 BSCF) and 6.2 × 10 8 - 6.4 × 10 8 ST m 3 (22.0–22.7 BSCF) gas were produced using the vertical and inclined well configurations, respectively. The analysis reveals that 2D reservoir models with homogeneous representations for porosity andmore » hydrate saturation significantly underestimate production potential. The heterogeneity implemented in this work provides complex porous network and preferential pathways for mobile phase flow to a producing well. Consequently, no secondary hydrate formation around a wellbore is predicted in contrast to models that utilize uniform porosity and hydrate saturation distributions.« less
Authors:
 [1] ; ORCiD logo [2] ;  [2] ;  [3] ;  [3]
  1. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); AECOM, Pittsburgh, PA (United States)
  2. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); West Virginia Univ., Morgantown, WV (United States)
  3. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
Publication Date:
Grant/Contract Number:
FE0004000
Type:
Accepted Manuscript
Journal Name:
Journal of Natural Gas Science and Engineering
Additional Journal Information:
Journal Volume: 35; Journal Issue: PA; Journal ID: ISSN 1875-5100
Publisher:
Elsevier
Research Org:
National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR (United States)
Sponsoring Org:
USDOE Office of Fossil Energy (FE)
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; 58 GEOSCIENCES
OSTI Identifier:
1478208

Myshakin, Evgeniy M., Ajayi, Taiwo, Anderson, Brian J., Seol, Yongkoo, and Boswell, Ray. Numerical simulations of depressurization-induced gas production from gas hydrates using 3-D heterogeneous models of L-Pad, Prudhoe Bay Unit, North Slope Alaska. United States: N. p., Web. doi:10.1016/j.jngse.2016.09.070.
Myshakin, Evgeniy M., Ajayi, Taiwo, Anderson, Brian J., Seol, Yongkoo, & Boswell, Ray. Numerical simulations of depressurization-induced gas production from gas hydrates using 3-D heterogeneous models of L-Pad, Prudhoe Bay Unit, North Slope Alaska. United States. doi:10.1016/j.jngse.2016.09.070.
Myshakin, Evgeniy M., Ajayi, Taiwo, Anderson, Brian J., Seol, Yongkoo, and Boswell, Ray. 2016. "Numerical simulations of depressurization-induced gas production from gas hydrates using 3-D heterogeneous models of L-Pad, Prudhoe Bay Unit, North Slope Alaska". United States. doi:10.1016/j.jngse.2016.09.070. https://www.osti.gov/servlets/purl/1478208.
@article{osti_1478208,
title = {Numerical simulations of depressurization-induced gas production from gas hydrates using 3-D heterogeneous models of L-Pad, Prudhoe Bay Unit, North Slope Alaska},
author = {Myshakin, Evgeniy M. and Ajayi, Taiwo and Anderson, Brian J. and Seol, Yongkoo and Boswell, Ray},
abstractNote = {Gas production potential is estimated using a three-dimensional reservoir model based on gas hydrate deposits located in the Prudhoe Bay region of the Alaska's North Slope. The model incorporates two hydrate-bearing sand units using detailed reservoir geological and structural information obtained from past and recent drilling programs. Geostatistical porosity models, conditioned to log data from 78 wells drilled in the vicinity of the Prudhoe Bay “L-Pad,” were developed, providing 3D heterogeneity in porosity, porosity-dependent hydrate saturation, and intrinsic permeability. The simulations utilize both vertical and inclined wellbores to induce depressurization of the reservoir at a constant bottom-hole pressure. The results show the superior performance of the inclined well design. Average gas production rates during the first five years were ~6.0 × 104 ST m3/day (~2.1 MMSCF/day) and ~2.7 × 104 ST m3/day (~1.0 MMSCF/day) for incline and vertical wells, respectively. After 30 years 5.3 × 108 - 5.7 × 108 ST m3 (18.6–20.2 BSCF) and 6.2 × 108 - 6.4 × 108 ST m3 (22.0–22.7 BSCF) gas were produced using the vertical and inclined well configurations, respectively. The analysis reveals that 2D reservoir models with homogeneous representations for porosity and hydrate saturation significantly underestimate production potential. The heterogeneity implemented in this work provides complex porous network and preferential pathways for mobile phase flow to a producing well. Consequently, no secondary hydrate formation around a wellbore is predicted in contrast to models that utilize uniform porosity and hydrate saturation distributions.},
doi = {10.1016/j.jngse.2016.09.070},
journal = {Journal of Natural Gas Science and Engineering},
number = PA,
volume = 35,
place = {United States},
year = {2016},
month = {9}
}