The goal of this project is to develop a high-resolution single-well seismic survey and monitoring system to efficiently and correctly 3D/4D image, characterize, and monitor sub-surface geological formations, structures, and properties at both large and small scales. Overall, this project is developing a multi-reservoir attribute mapping and monitoring system to provide a new level of understanding of shale reservoirs.

Paulsson, Inc. - Van Nuys, CA 91406

In the U.S., very large unconventional oil and gas (UOG) resources are found in shale deposits. According to a 2018 estimate in the Annual Energy Outlook 2020 by the Energy Information Administration (EIA), the volume of technically recoverable gas from gas shale is 2,829 trillion cubic feet (TCF) – enough for 92 years of consumption at the 2018 level of 31 TCF. EIA also estimates that in 2018 the U.S. possessed 44 billion barrels of technically recoverable shale oil. However, production of these shale gas and oil resources is often inefficient, with UOG oil recovery rates reported being as low as 5 – 8%. If an improved recovery can be designed and implemented a tremendous additional resource is available at known locations. The first step in this process is to generate better images that will lead to an improved understanding of these complex reservoirs.

Using borehole seismic receivers to record the data will improve the resolution by 2 – 4 times over the resolution provided by surface seismic sources and receivers since the seismic data only needs to penetrate the near surface attenuating formation once. The single-well seismic system developed in this project consists of clamped multi-component high-frequency vibratory seismic sources and high-fidelity receivers. The seismic data from this novel borehole seismic system will allow for both efficient and environmentally prudent development of UOG by simultaneously deploying two break-through seismic technologies in single UOG wells. The first technology is an ultra-sensitive, large-bandwidth, large-aperture, fiber-optic-based borehole 3C seismic vector sensor array that can be deployed in both vertical and horizontal wells to image the fracturing process and the location of the proppant in the fractures using data from passive and active seismic sources. The second technology is comprised of an ultra-large bandwidth, clamped borehole vector seismic source which is simultaneously deployed with the downhole receivers. This combined technology will image and monitor the geological formation and the hydraulic fractures with an ultra-high resolution.

This new borehole seismic, multi-reservoir attribute mapping and monitoring system would provide a new level of understanding of shale reservoirs that will increase production and resource recovery rates, while making the shale gas and oil production processes more sustainable and safer for surrounding communities through improvements in production efficiency and process control.

• Performed extensive modeling of several options for the downhole vibrator, leading to an understanding of the optimal size of the reaction mass and Terfenol actuator preload.
• Successfully completed a laboratory bench-scale test of the Downhole Vibratory Seismic Source (DVSS) prototype in conjunction with the FOSVS and demonstrated the compatibility of the two technologies.
• Designed and built a test fixture for the first prototype axial vibrator.
• The concept design of the 3C downhole seismic sources was completed.
• Completed the design of the appropriate power amplifier for the laboratory testing.
• The project team has determined the geophysical requirements for the seismic source actuators utilized in a high-resolution seismic system that records wide frequency band, and high- fidelity data in wells with different casing programs.

The clamped multi-component seismic vibratory source system has been designed and an axial prototype has been built. The prototype downhole seismic source was tested in a laboratory setting and in a small-scale field. The project team expects to be able to achieve a force in excess of 2,248 lbf (10,000 N) in the same broad frequency band during the next phase of the development project.

Additional directional seismic sources that will be included in the future will use torsional and radial source motions that generates complimentary radiation patterns.

$2,250,000

$0

NETL – Stephen Henry (stephen.henry@netl.doe.gov or 304-285-2083)
Paulsson – Björn Paulsson (bjorn.paulsson@paulsson.com or 310-780-2219)