Method and apparatus for evaluating multiple stage fracturing or earth formations surrounding a borehole
AssigneeDresser Industries, Inc.
InventorsWalter H. Fertl, Donald W. Oliver
Life of this patent
Estimating the term…
Abstract
A multiple stage formation fracturing operation is conducted with separate radioactive tracer elements injected into the well during each stage of the fracturing operation. After completion of the fracturing operation the well is logged using natural gamma ray logging. The resulting signals are sorted into individual channels or energy bands characteristic of each separate radioactive tracer element. The results of the multiple stage fracturing operation are evaluated based on dispersement of the individual tracer elements.
Claims8
A method for evaluating the artificial fracturing of earth formations traversed by a borehole, comprising the steps of:
- successively delivering into said borehole a fracture fluid, each successive delivery containing a radioactive tracer element having a unique gamma radiation energy characteristic;
- traversing said borehole with a gamma ray detector system;
- and
- selectively measuring radiations having energies characteristic of each of said tracer elements, said measurements indicating the profile of said artificial fracturing.
A method for evaluating multiple stage fracturing of earth formations traversed by a borehole, comprising the steps of:
- repeatedly injecting into said borehole a fracture fluid containing radioactive tracer elements, each injecting step having a tracer element emitting radiations of an energy different from the energies of radiations emitted by the other tracer elements;
- traversing said borehole with a logging instrument containing a natural gamma radiation detector;
- generating signals functionally related to the energy and frequency of gamma radiation detected by said detector;
- and
- separating said signals into a plurality of energy regions corresponding to the radiation produced by each of said radioactive tracer elements, said signals being indicative of the profile of said multiple stage fracturing.
A method of determining the distribution of radioactive tracer elements injected into subsurface earth formations during multiple stage fracturing, comprising:
- traversing a borehole penetrating said earth formations with a natural gamma radiation detector system;
- detecting natural gamma radiations emitting from said earth formations;
- and
- separating said detected radiations into energy regions functionally related to each of said tracer elements, said energy regions being representative of the distribution of said tracer elements in said subsurface formations.
A method for evaluating an artificial fracture in a subsurface earth formation traversed by a borehole, comprising the steps of:
- injecting a first fracture fluid containing a first radioactive tracer element into said formation;
- injecting a second fracture fluid containing a second radioactive tracer element into said formation;
- traversing said borehole with a natural gamma radiation detector;
- generating signals functionally related to natural gamma radiation detected by said detector;
- and
- separating said signals into two energy regions corresponding to the radiation produced by each of said first and second radioactive tracer elements.
Dependencies are inferred from the claim text.