Dean Gackle¹, Robert Flook², and Stewart Squires²

¹Channel Petroleum Inc., 32 Mountain Laurel Dr., Littleton, CO 80127
²HS Resources, Inc, 1999 Broadway, Suite 3600, Denver, CO 80202

ABSTRACT: 3-D Seismic Investigation of the D Sand Play, Hydrocarbon Saturated Window, D-J Basin, Colorado

Adjacent to the eastern and southern boundaries of Wattenberg Field, the lower Cretaceous D Sand is productive in an area that exhibits basin-center, hydrocarbon saturated characteristics. In this geographic region, the D Sand produces from stratigraphic traps within incised valley-fill sediments. The key elements of D Sand exploration success in the hydrocarbon-saturated zone are identification of prospective channel trends and detailing the distribution of reservoir quality sandstones filling channels incised on a lowstand erosion surface. An estimated 240 MMBO and 570 BCFG have been produced from the D Sand in the D-J Basin since its discovery in 1930; approximately 24 MMBO and 133 BCFG have been produced from incised valley-fill sandstones in the hydrocarbon-saturated zone.

Since 1993, HS Resources has acquired nine 3-D seismic surveys totaling 114 sq mi of data in the D-J Basin. The area of interest for HS Resources' exploration activity is limited to that portion of the D-J Basin that lies within the hydrocarbon-saturated window. Of nine 3-D seismic surveys acquired, eight have been successful in imaging the D Sand channel. Of those eight surveys, five have been economically successful and two are still being actively evaluated. The company utilizes an integrated approach, combining geology, geophysics, and reservoir engineering in its 3-D seismic exploration efforts. This approach to the D Sand Play has resulted in the discovery of the Spenson Field (1,100 MBO, 4.5 BCFG) and extensions of the Center Pivot (375 MBO, 1.5 BCFG) and the Lanyard (875 MBO, 3.0 BCFG) fields.

Variability in valley geometry and fill across the play area defines three play types. Each sub-play has different seismic attributes that can be investigated to mitigate exploration risk. 3-D seismic has been utilized to significantly reduce the drilling risks of the D Sand Play associated with each of these three models.

The integration of the nine 3-D seismic surveys acquired over different play types within the D Sand play has provided the necessary prospect characteristics for an overall successful project. The utilization of 3-D seismic in combination with detailed regional mapping can significantly reduce the historically high risks of exploring for the D Sand channels. The result of using an integrated approach, as described in this paper, can be a profitable play for the small to mid-size independent operator.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado