Reservoir pressure maintenance has strongly influenced ultimate cumulative recovery at Richview Field. The Cypress Formation has produced 200 million bbls of oil from 4,000 wells in Lawrence field since 1907. Its sandstone geometries were formed in a near-shore, shallow marine setting. In the central portion of the field, five distinct sandstone intervals are separated by thin impermeable shales. Although the total sand package is up to 60 ft thick, individual sandstones average only 10 ft thick.
Oil production is primarily from the middle three sandstones.
Tightly-cemented calcareous intervals less than one foot thick occur within the sandstones and act as barriers to fluid flow. Compartmentalization also occurs at a smaller scale where discontinuous shale layers that are a fraction of an inch thick form oil trapping compartments. Waterflooding Case Study Upper Cypress sandstone waterflood success at Sailor Springs Consolidated field is highly dependent on flow unit identification. Examples show that sandstone bodies mapped and defined by gross sandstone isopachs do not necessarily flood successfully. Offsetting wells drilled on ten-acre spacing may also appear to produce from grossly correlative sandstones although no communication is established during water injection.