Reservoir assessment of the Pennsylvanian Hartshorne sandstone, central Arkoma Basin, Arkansas

The objective of this study is to assess the reservoir characteristics of the Hartshorne Formation for potential production in the Paris syncline, central Arkoma basin. This was accomplished through extensive subsurface investigation of well logs and delineation of formational and facies trends within the study area. Reservoir quality parameters porosity and saturation were calculated from well log data. Surface work involved fracture orientation mapping and observation of facies at outcrop on the periphery of the Paris syncline. Three surface to subsurface cross sections were made in order to project observed facies in outcrop into the subsurface.; The Hartshorne Formation displays a shoestring sandstone trend typical of a channel body in the study area. The high vertical and lateral variability of this deposit introduces a level of risk in reservoir geometry prediction. Saturation calculation was inconclusive with available data. Porosity values are low in the Hartshorne Formation, with relatively porous intervals mostly confined to basal sandstone beds. The Hartshorne is highly fractured. Fractures have a dominant northern strike on both Prairie View and Pine Ridge anticline, suggesting that these fractures may propagate into the subsurface, creating a degree of secondary porosity. The Hartshorne fits into the tight gas unconventional play category with stratigraphic style trapping, low porosity and low permeability. Cross-over in bulk density-neutron combination logs suggests the presence of gas, but reservoir stimulation techniques would be necessary for production.