Dezhi Chu

US Patent:

8332154, Dec 11, 2012

Filed:

Mar 16, 2010

Appl. No.:

12/725062

Inventors:

Dezhi Chu - Bellaire TX, US

Assignee:

ExxonMobil Upstream Research Company - Houston TX

International Classification:

G01V 1/28
G06F 19/00

US Classification:

702 11, 367 38, 367 73, 702 14, 702 17

Abstract:

Method for deriving a reservoir property change data volume from time shifts used to time-align 4D seismic survey data (). The time alignment is performed on at least one angle stack of 4D data to determine a time-shift data volume (). When multiple angle stacks are used, the time shifts are corrected to zero offset. A running time window is defined, and within each window the time shifts are best fit to a straight-line function of time (depth), one angle stack at a time (). The slopes from the straight line fits from different angle stacks are averaged at each voxel in the data volume, which yields a reservoir properties (Δν/ν) data volume (). This data volume may be filtered with a low-pass filter to improve signal-to-noise (). The resulting data volume may be merged with the 4D data volume to expand its bandwidth (), or it may be converted into a reservoir saturation and pressure change data volume () using a rock-physics model ().

US Patent:

8451683, May 28, 2013

Filed:

Mar 8, 2010

Appl. No.:

12/719566

Inventors:

Dezhi Chu - Bellaire TX, US
Ganglin Chen - Houston TX, US

Assignee:

ExxonMobil Upstream Research Company - Houston TX

International Classification:

G01V 1/30

US Classification:

367 38

Abstract:

A method including analyzing seismic data relating to a producing hydrocarbon reservoir is disclosed. The seismic data includes first and second sets of seismic data obtained at different times. An interval composed substantially of hard rock is identified in the hydrocarbon reservoir. 4D seismic attributes for the region are calculated. Rock physics relationships are applied to seismic data related to the interval according to the permeability associated therewith. A fluid saturation change or a pressure change of the interval is inferred based on outputs of the first or second sets of rock physics relationships and the calculated 4D attributes for the interval. The inferred fluid saturation change or pressure change of the interval is outputted.

US Patent:

20100161230, Jun 24, 2010

Filed:

Nov 25, 2009

Appl. No.:

12/625809

Inventors:

Dezhi Chu - Houston TX, US

International Classification:

G01V 1/28

US Classification:

702 14

Abstract:

A method for predicting differences in subsurface conditions useful in 4D applications. In an example embodiment of the method, at least one layer is defined in a data volume representing a first subsurface condition such as shale volume fraction (). An exhaustive search methodology is then performed over a second subsurface condition such as pressure or saturation for some or all of the first subsurface condition data points () based on a data fit of synthetic geophysical data to measured geophysical data. The exemplary method may additionally comprise performing a statistical analysis to determine whether the error in data fit is significantly reduced () if one of the layers is divided into two or more layers (). The layer is divided into multiple layers () if the error is significantly reduced (). In this manner, the measured survey data are inverted to predict values of the second subsurface condition.

US Patent:

20180275303, Sep 27, 2018

Filed:

Mar 5, 2018

Appl. No.:

15/912201

Inventors:

Xin Zhan - Sugar Land TX, US
Dezhi Chu - Houston TX, US
John E. Bishop - Houston TX, US
Xinyou Lu - Bellaire TX, US
David D. McAdow - Houston TX, US
Brent D. Wheelock - Houston TX, US

International Classification:

G01V 1/30
G01V 1/28

Abstract:

A method for inversion of 4D seismic data, the method including: determining time shift between baseline and monitor geophysical datasets; determining time strain from the time shift; iteratively repeating until a stopping criteria is satisfied, performing an iterative elastic AVO inversion with a 4D difference providing an update, from an initial model including the time strain, to generate an updated time strain and an updated physical property model, wherein the stopping criteria is a misfit between synthetic data generated from the updated physical property model and the 4D difference being within a predetermined noise level, wherein for each successive iteration, the method includes generating an updated time shift from the updated time strain, generating an updated 4D difference from the updated time strain, generating a new time strain from the updated 4D difference, and repeating the AVO inversion with the updated 4D difference and the new time strain; generating final values for the physical property model; and converting, with a rock physics model or a reservoir simulation model, the final values to saturation and/or pressure changes for a subsurface region.