Maturity Indicator Measurement using Novel Electron Paramagnetic Resonance Sensor

Abstract

Electron Paramagnetic Resonance (EPR) sensor systems can be used to measure free radicals and transitional metals in certain oxidation states, such as Mg2+ ,Mn2+,Co2+, Cu2+, Ni2+, and Fe2+. Organic free radicals are present in asphaltenes and in kerogen. Free radical concentration can be used as a maturity indicator for kerogen/oil. Traditionally, EPR sensors use a resonant electromagnetic cavity and a permanent magnet for measurements, which limits their size and makes them difficult to be miniaturized. In current EPR sensors the sample size is limited to several millimeters. In this work, we demonstrate an EPR sensor without the traditional transmission resonant cavity. An EPR measurement can be used as a maturity indicator for kerogen/oil, since it responds to free radicals present in organic matter. The advantage of the EPR sensor is that it can be designed to respond to kerogen material present in the source rock. Our EPR sensor is manufactured out of materials capable of withstanding borehole conditions. We intend to package this device in a small form factor such that it can be deployed into a 1 inch logging tool. Using such an EPR logging tool, we can identify sweet spots in horizontal wells and optimize the unconventional play. We will present data for several oil samples, as an example of oil maturity, and vanadyl porphyrin measurements. We will demonstrate that the EPR signal can be uniquely attributed to kerogen and can be easily correlated to a Hydrogen Index. The EPR imaging has a spatial resolution of 0.3 mm and can be used for heterogeneous samples such as source rocks. We will discuss the implementation of an EPR imaging system which could be used for core scanning/well logging.

Keywords

• optical sensors
• cmos sensors
• arduino
• fluorescence
• downhole tool
• oil density