Improvement of Water Flood Performance of Low- Permeability Sandstone Reservoirs

Tong, Zhengxin¹, Peigui Yin¹, Norman R. Morrow¹, Dennis J. Brabec² (1) University of Wyoming, Laramie, WY (2) Nerd Gas Company, LLC, Casper,

Frontier sandstones are among the major oil producers in Wyoming but oil recovery is low. Water flooding is not widely practiced because water injectivity is low. The present work concerns improved oil recovery through a combination of reservoir description and laboratory experiments. The sandstone samples used in this study are characterized by low permeability (from 1.9 to 4.2 md) and moderate porosity (from 13.6% to 16.1%). Kaolinite and chlorite are abundant in these sandstones, and porosity is dominated by poorly-connected dissolution pores and micropores within clay minerals and chert grains. Laboratory tests indicated that Frontier sandstone cores are strongly water-wet. Oil recovery by laboratory water flooding was about 50%; however, reservoir recovery is less than 20% in current waterflooding operations in the field. Improvement of water injectivity is proposed as a cost effective way to increase oil recovery from these low-permeable sandstones.

AAPG Search and Discovery Article #90055©2006 AAPG Rocky Mountain Section Meeting, Billings, Montana