INTEGRATION OF NEW TECHNOLOGIES TO IMPROVE STIMULATION TREATMENTS IN SHALE GAS PLAYS: COUPLING MICROSEISMIC MAPPING, IMAGE AND ELECTRIC LOGS IN THE BARNETT SHALE FORMATION

Considerable volumes of gas are currently being produced from unconventional Mississippian shale reservoirs such as the Barnett Shale in Texas and the Fayetteville Shale in Arkansas. Similarly, the organic-rich shale gas fields underlying the Appalachian, Illinois and Michigan basins could potentially become the most productive source of natural gas in the northeast United States. These plays are partly technology driven and partly economics-driven. Traditional and more modern well log evaluation techniques and completion methods are required to economically produce these types of plays. Among many, two main geologic factors govern the production from these gas-bearing formations: ultra-low matrix porosity and permeability as well as fracture-induced permeability. These shales are extremely low porosity reservoirs that must be effectively hydraulically fracture stimulated. Additionally, analysis of these gas fields illustrates how structural geology (by the means of basement structure influence, differential shortening effect, etc.) as well as sequence stratigraphy and depositional history yields stress field variations both laterally and with depth.

To avoid making too many assumptions as to the induced fracture geometry and to better understand the created fracture geometry for various completion designs, monitoring of the induced microseismic activity may be used. Advanced processing algorithms and transmission techniques allow an on-site geophysicist to process large amount of data and to deliver microseismic hypocentral locations in a matter of seconds to a viewer located anywhere in the world. Integration of mapped induced microseismic activity, wellbore images and sonic logs can bring additional valuable information to help understand the nature of the reservoir and the hydraulic treatment behavior. Using examples from the Barnett Shale play, this paper highlights the use of real-time microseismic monitoring of hydraulic fracture treatments to allow on-the-fly changes in fracture design as well as changes in perforation strategy and re-stimulation designs to maximize the reservoir volume effectively contacted by the stimulation treatment. This paper further correlates microseismic activity to log data and illustrates how logs can be used to estimate fracture geometry.