A Reconfigurable Ultra Low Frequency Triaxial Induction Tool for Fracture Diagnostics

Hydraulic fractures must be contained within the target formation so that they do not contact and potentially contaminate sources of drinking water. To mitigate this risk, research is needed to develop technologies that will advance our ability to diagnose, quantify, and map hydraulic fractures and thus help mitigate the danger that hydraulic fracturing results in the contamination of subsurface potable water reservoirs. Specifically, the challenge is to develop a new technology to more accurately and cost effectively characterize the dimensions, orientation, and proppant distribution of hydraulic fractures in near real time as well as provide long-term monitoring capabilities of these same parameters in cased wells. Currently, induction tools that are placed in the wellbore to make measurements are severely limited in sensing and resolution capabilities. In this project, we will adopt and integrate signal processing technologies to design an extremely low-frequency triaxle induction tool with improved aggregate receiver sensitivity and greater noise rejection. Compared to current downhole induction based measurements, the proposed tool will achieve greater range and resolution when measuring fractures generated with electrically conductive proppant in open holes. Based on the findings recently published, it should be anticipated that improving sensitivity and noise performance will allow for the (i) detection of larger fractures by facilitating increased spacing between the transmit and receive elements of the tool, (ii) differentiation of fracture sizes with higher resolution (and also detection of smaller fractures), (iii) detection of propped regions that have lower contrast (are less electrically conductive) with the background shale, and (iv) identification of dipping fractures with smaller dip angles by copolarized rather than coaxial measurements. The primary objective of the Phase I effort was to demonstrate the feasibility of utilizing the existing proprietary core signal processing technologies to improve the efficacy of Low Frequency Electromagnetic Induction (LFEI) based propped fracture length measurements. This capability is valuable to achieve because it will significantly enhance the ability to collect data associated with hydraulic fracturing operations of shale gas plays and improve our ability to identify and remediate potential ground water contamination outcomes. In Phase II, a prototype tool will be fully designed and operationally deployed.