EP-4735917-A2 - SUBSURFACE FLUID DETECTION

Abstract

A method of detecting subsurface conditions conducive to fluid transfer can include obtaining microseismic resonance signals from multiple surface locations over a subsurface region of interest using a resonance sensor, wherein for at least a plurality of the multiple surface locations, multiple microseismic resonance signals are obtained at different times to generate signal stacks. In some examples, the method can also include amplifying the microseismic resonance signals, filtering out the high frequencies at least above about 7,500 Hz leaving low frequencies at least as low as about 4 Hz for evaluation, and using these low frequencies to identify subsurface fracture zones where subsurface fluid may be present. In some examples, subsurface fluids can be detected and/or mapped using gamma radiation count and/or magnetometric density data collected using appropriate equipment.

Inventors

• JESSOP, Michael, L.
• LUKER, David, J.
• COOK, Justin, A.
• KOFOED, Val, O.

Assignees

• Willowstick Technologies LLC

Dates

Publication Date

20260506

Application Date

20240701

Claims (20)

1. CLAIMS What Is Claimed Is: 1. A method of detecting subsurface conditions conducive to fluid transfer, comprising: obtaining microseismic resonance signals from multiple surface locations over a subsurface region of interest using a resonance sensor, wherein for at least a plurality of the multiple surface locations, multiple microseismic resonance signals are obtained at different times to generate signal stacks; amplifying the microseismic resonance signals; filtering out the high frequencies at least above about 7,500 Hz leaving low frequencies at least as low as about 4 Hz for evaluation; using the low frequencies, identifying subsurface fracture zones where subsurface fluid may be present.
2. 2. The method of claim 1, wherein signal stacks are processed to generate modified microseismic resonance signal that represents the multiple microseismic resonance signals.
3. 3. The method of claim 1, wherein the signal stacks are processed to generate a mean microseismic resonance signal, an arithmetic mean microseismic resonance signal, a geometric mean microseismic resonance signal, a median microseismic resonance signal, a mid-point microseismic resonance signal, a microseismic resonance signal with outlier signal filtered out, or a combination thereof.
4. 4. The method of claim 1, wherein the signal stacks are based on 2 to 10 sequentially obtained microseismic resonance signals.
5. 5. The method of claim 4, wherein the 2 to 10 individually obtained microseismic resonance signals are obtained within about 15 minutes. 10 minutes.
6. 6. The method of claim 1, wherein the resonance sensor is placed directly on the multiple surface locations where microseismic resonance emissions are measurable.
7. 7. The method of claim 1, wherein a spike is driven through the multiple surface locations and into the subsurface region of interest at a depth ranging from at least one inch to a depth where microseismic resonance emissions are reliably measurable.
8. 8. The method of claim 1, wherein amplifying the microseismic resonance signal includes amplification with a multi-stage amplifier.
9. 9. The method of claim 8, wherein the multi-stage amplifier provides multiple levels of amplification up to at least 16:1 gain.
10. 10. The method of claim 8, wherein the multi-stage amplifier provides multiple levels of amplification up to at least 64:1 gain.
11. 11. The method of claim 1, wherein filtering the microseismic resonance signal is carried out using a maximally flat magnitude filter.
12. 12. The method of claim 1, wherein individual microseismic resonance signals are obtained onboard a microseismic resonance detector which also collects onboard location data.
13. 13. The method of claim 12, wherein the onboard location data collected on the microseismic resonance detector is from an onboard receiver adapted for use with a global navigation satellite system.
14. 14. The method of claim 12, wherein the onboard location data collected on the microseismic resonance detector includes using an onboard receiver adapted to receive RF signal from a terrestrial base station source and a second reference signal.
15. 15. The method of claim 12, wherein the onboard location data collected on the microseismic resonance detector includes an on-board receiver adapted for real-time kinematic positioning.
16. 16. The method of claim 1, wherein the resonance sensor has a sensitivity suitable for sensing frequencies within the range of about 4 Hz to about 800 Hz.
17. 17. The method of claim 1, wherein amplifying the microseismic resonance signals and filtering out the high frequencies is carried out as analog signals to obtain the low frequencies, and wherein the low frequencies are converted to a digital signal for digital processing.
18. 18. The method of claim 1, wherein at least some of the digital processing occurs onboard a microseismic resonance detector.
19. 19. The method of claim 1, wherein at least some of the digital processing occurs remotely after transfer to a computer or a network.
20. 20. The method of claim 1, wherein filtering out the high frequencies includes retaining all low frequencies below the high frequencies that are filtered out.

Description

SUBSURFACE FLUID DETECTION BACKGROUND Current techniques for tracking groundwater or subsurface fluids typically involve geophysical methods such as various forms of galvanic resistivity, electromagnetic conductivity, nuclear magnetic resonance, or the drilling of many observation wells for monitoring. Other forms of tracking and monitoring rely on the measurement of magnetic fields created by electric currents flowing through underground water pathways, often referred to as the magnetometric approach. Drilling is an option for identifying and/or tracking subsurface water, but this can be a lengthy and expensive process with much guesswork involved. BRIEF DESCRIPTION OF THE DRAWINGS FIG.1 schematically illustrates an example device or system for detecting subsurface water from microseismic resonance (MSR) in accordance with the present disclosure; FIG.2 schematically illustrates an example device or system for detecting subsurface water based on near-surface gamma radiation emission in accordance with the present disclosure; FIG.3 schematically illustrates an example device or system for detecting subsurface water using magnetometric density (MMD) in accordance with the present disclosure; FIG. 4 illustrates example subsurface signal collected from a region of land using microseismic resonance technology in accordance with the present disclosure; FIG.5 illustrates example subsurface signal collected from a region of land using gamma radiation technology in accordance with the present disclosure; FIG.6 illustrates example subsurface signal collected from a region of land using magnetometric density technology in accordance with the present disclosure; FIG.7 is a schematic drawing depicting a subsurface cross-sectional area of interest showing information that can be ascertained by the use of multiple subsurface detection technologies in accordance with the present disclosure; and FIG.8 provides comparative subsurface microseismic resonance measurements which illustrates enhanced resolution that can be obtained by using signal stacking. DETAILED DESCRIPTION The technology described herein can use the detection of one or more of microseismic resonance, gamma radiation, and/or magnetometric field to detect subsurface fluids, particularly water, with reasonable accuracy. As an initial note, when referring to “detecting” subsurface fluids herein, this includes fluid discovery, fluid mapping, fluid monitoring, and/or detecting conditions highly conducive to fluid transport which may enable extension of the typical wellbore reach and thereby increase production. In some instances where other fluids, such as oil or methane or the like, are being targeted even for deep discovery, microseismic resonance can be a particularly useful tool. Furthermore, when referring to “subsurface” fluids or “subsurface body of” fluid, e.g., water, oil, gas, etc., this includes any fluid content beneath the surface being tested, including reservoirs of subsurface fluids, flowing subsurface fluids, subsurface springs under pressure, subsurface moisture content contained with earth material such as fields of rock, gravel, sand, clay, etc., subsurface reservoirs of hydrocarbons, e.g., oil or gas, or any other subsurface dispersed or pooled collection of fluids that may be found beneath a surface of the earth or other large structure, e.g., industrial underground water channels, fluids coursing through a dam, etc. In accordance with this, a method of detecting subsurface conditions conducive to fluid transfer can include obtaining microseismic resonance signals from multiple surface locations over a subsurface region of interest using a resonance sensor or sensors, e.g., piezoelectric sensor(s) or other sensors suitable for use with geophones. For at least a plurality of the multiple surface locations, multiple microseismic resonance signals can be obtained at different times to generate signal stacks. This method can also include amplifying the microseismic resonance signals, filtering out the high frequencies at least above about 7,500 Hz leaving low frequencies at least as low as about 4 Hz for evaluation, and using these low frequencies to identify subsurface fracture zones where subsurface fluid may be present. In some examples, filtering out the high frequencies may include retaining all low frequencies below the high frequencies that are filtered out, e.g., everything below 7,500 Hz is kept. In another example, a method of detecting subsurface water or conditions conducive to subsurface water can include obtaining a gamma radiation count from multiple surface locations over a subsurface region of interest using a gamma radiation detector having an inorganic scintillation detector selected from a cesium halide crystal, cerium halide crystal, lanthanum halide crystal, or bismuth germinate crystal. This method can also include determining a background gamma radiation count over at least a portion of the subsurface region of intere