Airborne Measurement of Transient Pulses Locates Hydrocarbon Reservoirs
Leonard A. LeSchack1 and John R. Jackson2
1 Hectori Inc, Calgary, AB
2 Pinemont Technologies Inc, Littleton, CO
Author Jackson recently patented a passive geophysical prospecting method and apparatus that both in its ground-borne mode, as well as in its airborne configuration, have successfully identified, in blind tests, hydrocarbon reservoirs previously located by author LeSchack using independent geophysical surveys. LeSchack's surveys have been described earlier in the literature. The Jackson method—especially in its airborne configuration—can reduce the cost of exploration by high-grading prospective land for further on-the-ground geochemical and geophysical surveys. It works over land and water. Areas along the Gulf Coast, and East and South Texas were flown identifying promising locations for drilling. To date, 15 productive wells have been drilled largely on the basis of this method.
The Jackson method is based on the following theory. A primary magnetic field of electromagnetic energy is generated by the earth. It can be sensed at the earth's surface, and from low-flying aircraft. Within vertical components of this primary field, there exist random impulses of energy manifested in the audio-frequency range. Secondary magnetic fields associated with the microseepage plumes over hydrocarbon reservoirs (Pirson Redox cells), interact with the random impulses in the primary field and generate secondary impulses. Although speculative, it is widely believed that the impulses are related to lightning activity around the Earth. Regardless of their source, however, the existence of random occurring impulses is recognized. The number of impulses per second over any area is related to the strength of the hydrocarbon-induced secondary magnetic fields. Count rate increases exceeding 100 counts/second have been observed over hydrocarbon reservoirs. The local impulse density together with associated GPS data can be mapped easily, permitting direct interpretation by the geologist.