Events

Dr. Carl Sondergeld, Professor and the Mewbourne Chair in the Mewbourne School of Petroleum and Geological Engineering, will give a talk entitled "Shale Heterogeneity…a Surprise?" as part of the Claude R. Hocott Graduate Seminar Series.

Bio: Dr. Carl Sondergeld is Professor and the Mewbourne Chair in the Mewbourne School of Petroleum and Geological Engineering. He has been at OU for 11 years. He worked at Amoco Research for 19 years and is author or coauthor on 14 US Patents. He was most recently the Society of Exploration Geophysicists Distinguish Lecturer for the Fall of 2010. His current research focuses on petrophysics and seismic rock physics as it applies to gas shales. His research leads to improved ways of identifying and exploiting natural gas, the bridging fuel for America. He currently operates an industrial sponsored research consortium on "Experiment Rock Physics" with his colleague of 30 years, Dr. Chandra Rai. Together they have also initiated an internationally sponsored industrial research effort for gas shale, the "Shale Gas Consortium."

Abstract:
Shale is defined based on grain size (~4μm); there is no restriction on coposition. Often associated with this particle size are clays and organics. World average mineralogies suggests shales are dominated by quartz and clays. Clearly, the Eagle Ford and Niobrara are notable exceptions. Drilling and completion activity indicates that only 25-30% of shale acreage is "core." Furthermore, in those core areas, rock quality as reflected in production appears quite variable. Analysis of the stage efficiency suggests 30-40% of stages are ineffective. A recent EIA shale study has downgraded the reserves of a number of resource plays in recognition of the impact of "shale heterogeneity." Imagine an operator with a 2000 well program where each completion involves 10 stages but only 7 out of 10 are actually productive. If each stage costs about $100,000, he is wasting roughly $600,000,000. If we could save on average 1 stage per well, he would save $200,000,000 and the attendant lost time to complete 2000 stages. Shale heterogeneity occurs at all scales: basin wide, seismic, outcrop, wellbore, core, plugs, thin section and SEM and TEM scales. Furthermore heterogeneity is manifest in matrix composition, fractures, hydrocarbon volumes and petrophysical properties. Heterogeneity presents challenges in its assessment and quantification as well in completion strategies. These challenges are exacerbated by the need to reduce costs, reluctance to retrieve core, and the limited logging executed in horizontal boreholes. It would be useful to assess heterogeneity as the drillbit progresses; however, the resulting cuttings, a byproduct of drilling, are compromised by the widespread use of PDC bits. The cuttings are extremely small and mechanically compromised rendering them almost useless for petrophysical and mechanical studies. So then, how can we assess shale heterogeneity in a time frame to impact decisions? A partial answer lies in the growing suite of downhole measurement tools. After examining examples of heterogeneity, I will discuss technologies and strategies which with minor modifications can address this issue. Coupling new drillbit technologies with classical petrophysical measurement techniques as well as new techniques can take us a long way in addressing the shale variability which could factor directly into completion strategies.