TY - JOUR
T1 - An evaluation of pore pressure diffusion into a shale overburden and sideburden induced by production-related changes in reservoir fluid pressure
AU - Ricard, Ludovic
AU - MacBeth, Colin
AU - HajNasser, Yesser
AU - Schutjens, Peter
PY - 2012/6
Y1 - 2012/6
N2 - It is commonplace in the simulation of reservoir fluid flow induced by hydrocarbon production to regard shales as barriers to flow. Whilst this appears correct for fluid exchange, this is not the case for the fluid pressure component of this process. Indeed, the authors observe that pore pressure reduction due to reservoir depletion can propagate significant distances into the shale overburden or sideburden over the production time scale. Shales may deplete their pore pressures by more than 10% of that experienced in the reservoir sand for distances of tens of metres to kilometres into the shale, depending on the production history, duration and the specific shale properties. An important factor controlling these results is heterogeneity of the shale sediments, and the pressure diffusion process can be considerably enhanced by the presence of silt laminations and streaks. These results suggest a possible risk to drillers when advancing towards the top of a depleting reservoir or when drilling a well alongside an already depleted reservoir. Our analyses conclude that pore pressure diffusion should be considered as a factor in geomechanical and fluid flow reservoir modelling, and in mud weight determination during infill drilling.
AB - It is commonplace in the simulation of reservoir fluid flow induced by hydrocarbon production to regard shales as barriers to flow. Whilst this appears correct for fluid exchange, this is not the case for the fluid pressure component of this process. Indeed, the authors observe that pore pressure reduction due to reservoir depletion can propagate significant distances into the shale overburden or sideburden over the production time scale. Shales may deplete their pore pressures by more than 10% of that experienced in the reservoir sand for distances of tens of metres to kilometres into the shale, depending on the production history, duration and the specific shale properties. An important factor controlling these results is heterogeneity of the shale sediments, and the pressure diffusion process can be considerably enhanced by the presence of silt laminations and streaks. These results suggest a possible risk to drillers when advancing towards the top of a depleting reservoir or when drilling a well alongside an already depleted reservoir. Our analyses conclude that pore pressure diffusion should be considered as a factor in geomechanical and fluid flow reservoir modelling, and in mud weight determination during infill drilling.
U2 - 10.1088/1742-2132/9/3/345
DO - 10.1088/1742-2132/9/3/345
M3 - Article
VL - 9
SP - 345
EP - 358
JO - Journal of Geophysics and Engineering
JF - Journal of Geophysics and Engineering
SN - 1742-2132
IS - 3
ER -