The Eva South Morrow Sand Unit is located in western Texas County, Oklahoma. The field produces from an upper Morrow sandstone, termed the Eva sandstone, deposited in a transgressive valley-fill sequence. The field is defined as a combination structural stratigraphic trap; the reservoir lies in a convex up -dip bend in the valley and is truncated on the west side by the Teepee Creek fault. Although the field has been a successful waterflood since 1993, reservoir heterogeneity and compartmentalization has impeded overall sweep efficiency. A 4.25 square mile high-resolution, three component three-dimensional (3C3D) seismic survey was acquired in order to improve reservoir characterization and pinpoint the optimal location of a new horizontal producing well, the ESU 13-H. Extensive modeling was conducted prior to seismic acquisition to predict the seismic response and define acquisition parameters. Although the seismic did not define any new undeveloped reservoir compartments, the P-wave data was successful in providing excellent detail of the structural configuration of the field and adequate resolution of reservoir extents and geometry. The PSV converted-wave data appears to have defined reservoir extents and geometry, although with a probable overprint from acquisition geometry and principle stress fields. In general, the P-wave data proved to be a valuable exploration and development tool, though not capable of defining all reservoir complexities for detailed reservoir engineering. The PSV converted-wave data showed promise for future applications of this evolving technology. The seismic data were utilized to locate the ESU 13-H horizontal well parallel to, and within 200 feet of the Teepee Creek fault in an area thought to contain additional reserves. The reservoir development was as expected, although only approximately 1000 feet of the planned 2800 feet of horizontal drilling was achieved prior to the well becoming permanently stuck. Despite this setback, the well was successful in adding 122 MBO of incremental reserves, representing 1.7% of the original oil in place (OOIP) in the field; targeted incremental reserves were 150 MBO, or 2.0% of the OOIP. Conclusions are that high-resolution 3C3D seismic and horizontal wells are effective tools for improving reservoir characterization and sweep efficiency in Morrow and other (DOE) Class 1 reservoirs.