VARIABLE SCALES OF SEDIMENTATION IN THE WOLFCAMP FORMATION, MIDLAND BASIN, TX

The Wolfcamp Formation in the Midland basin of Texas contains complex depositional fabrics and styles that vary from the basin to centimeter scale. This variability implies multiple depositional mechanisms that are dependent on the complex interplay of basinal architecture and proximity to carbonate platforms. Since 2008, hydrocarbon production from the Wolfcamp Formation in the Midland basin has skyrocketed in large part due to horizontal completions. Completing within optimal formation targets maximizes potential hydrocarbon recovery from individual wells within the Midland Basin. In this study, core description was coupled with traditional wireline well log analysis and handheld x-ray fluorescence (XRF) techniques to high-grade target intervals within the Wolfcamp Formation.

Stratigraphic architecture across the basin is established using wireline log correlations. These correlations provide a basinal-scale context into which stratigraphic and sedimentological interpretations are placed. Core observations of several wells document key lithological characteristics and define resultant lithofacies. Within these identified lithofacies, a wide range of physical mechanisms of sediment transport and deposition are inferred. Depending on location within the basin, individual depositional processes have increased importance – mega-breccias are most common adjacent to high angle carbonate platforms, while traction current deposits are more common distal to carbonate platforms. Patterns in lithologic heterogeneity observed in core are also observed in elemental concentration measurements. Intervals that chemostratigraphically imply enhanced preservation potential of organic matter occur episodically throughout the cored sections, indicating a sequence stratigraphic relationship. Various lithofacies assemblages are interbedded to form play-defining source/reservoir coupling styles. Ongoing work will examine ideal completion methods for different source/reservoir couplings (e.g. in situ reservoirs versus micro-coupled reservoirs).