Characterizing Induced Fractures Using Trapped Waves – What Do We Want to Know? What Can We Learn?

Abstract:

It has been said in the oil and gas industry that fracture modeling and prediction can tell us everything we want to know about the characteristics of hydraulically induced fractures – except their width, length, height, and conductivity. In other words, classical models fail in almost every regard to provide unambiguous knowledge that would enable better predictions of production and better design of stimulation practices. With the advent of microseismic monitoring of stimulations the industry has been given hope that that this may soon change, however information gleaned from these records about the locations, timing, and characteristics of induced events is almost equally ambiguous. Recent analyses are beginning to suggest that energy radiated from fractures as they propagate, usually episodically, and resonate due to pressure pulses, flow turbulence and other sources of energy within the fluid-filled fracture and the wellbore may provide information to determine length, compliance, surface roughness, and other attributes from which the effective length of fractures can be determined both while injecting and after closure as fluid leaks off. This talk highlights the key issues facing the oil and gas and geothermal industries, and provides some examples from recent work to illustrate the extent to which it may be possible to use radiated energy for fracture characterization.