# US 10,768,324 B2 · Method to predict pore pressure and seal integrity using full wavefield inversion

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- Number: US 10,768,324 B2
- Document ID: US10768324B2
- Status: Granted
- Kind: B2
- Application number: 15/485,395
- Filed: 2017-04-12
- Published: 2017-11-23
- Granted: 2020-09-08
- Earliest claimed: 2016-05-19
- Assignees: ExxonMobil Upstream Research Company
- Applicants: Stan Lee; Prajnajyoti Mazumdar; Ratnanabha Sain
- Inventors: Stan Lee; Prajnajyoti Mazumdar; Ratnanabha Sain
- Web page: https://patentgrep.com/patent/US10768324B2

## CPC

- G01V 1/306: {for determining physical properties of the subsurface, e.g. impedance, porosity or attenuation profiles}
- G01V 1/282: {Application of seismic models, synthetic seismograms}
- G01V 1/303: {for determining velocity profiles or travel times}
- G01V 2210/614: Synthetically generated data
- G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02)

## Abstract

A method, including: generating a velocity model for a subsurface region of the Earth by using a full wavefield inversion process; generating an impedance model for the subsurface region of the Earth by using a full wavefield inversion process; and estimating pore pressure at a prediction site in the subsurface region by integrating the velocity model and the impedance model with a velocity-based pore pressure estimation process.

## Claims

### Claim 1

A method, comprising:
generating a velocity model for a subsurface region of the Earth by using one or more full wavefield inversion processes;
generating an impedance model for the subsurface region of the Earth by using one or more full wavefield inversion processes;
estimating pore pressure at a prediction site in the subsurface region by integrating the velocity model and the impedance model with a velocity-based pore pressure estimation process, wherein the prediction site includes a reservoir rock, and wherein the velocity-based pore pressure estimation process comprises:
identifying, within the impedance model, the reservoir rock;
using the velocity model to determine or estimate shale pore pressure at a base of the reservoir rock in the impedance model;
determining a buoyancy pressure of a fluid assumed to fill a column height of the reservoir rock; and
the estimating the pore pressure for the reservoir rock includes combining the shale pore pressure at the base of the reservoir rock and the buoyancy pressure;
charactering a mechanical seal integrity of the subsurface region using the estimated pore pressure; and
managing hydrocarbons in the subsurface region using the estimated pore pressure and mechanical seal integrity.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
predicting a lithology volume for the subsurface geologic formation from the impedance model;
determining Poisson's ratio within the reservoir rock based on the lithology volume and P-wave velocity from the velocity model generated using the full wavefield inversion process; and
determining a full wavefield inversion lithology-based minimum horizontal stress from the Poisson's ratio.

### Claim 3 (depends on 2)

The method of claim 2, further comprising:
analyzing seal integrity of the reservoir rock based on a difference between the estimated pore pressure and the minimum horizontal stress.

### Claim 4 (depends on 3)

The method of claim 3, wherein the reservoir rock is sand.

### Claim 5 (depends on 2)

The method of claim 2, wherein the predicting the lithology volume includes using impedance values from an offset well.

### Claim 6 (depends on 1)

The method of claim 1, wherein the fluid is one of oil, gas, or water.

### Claim 7 (depends on 1)

The method of claim 1, wherein managing hydrocarbons comprises extracting hydrocarbons from the reservoir rock.