System and method for determining fluid viscosity of a fluid in a rock formation

Patent metadata

Field	Value
Publication number	US-9835609-B2
Application number	US-201514668361-A
Country	US
Kind code	B2
Filing date	Mar 25, 2015
Priority date	Mar 25, 2015
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

A system and a method are provided for determining a viscosity of a fluid in a rock formation. The method includes determining a Stoneley mobility using a Stoneley wave measurement in a rock formation containing a fluid; determining a wireline formation tester (WFT) downhole fluid analysis (DFA) mobility by using a wireline formation tester in the rock formation; and determining a viscosity of the fluid based on the Stoneley mobility and the wireline formation tester (WFT) downhole fluid analysis (DFA) mobility.

First claim

What is claimed is:

1. A method of determining viscosity of a fluid in a rock formation, the method comprising:
using a sonic logging tool to perform a Stoneley wave measurement in a rock formation containing a fluid;
using one or more computer processor units to determine a Stoneley mobility by inversion using Stoneley complex phase velocity equations and the Stoneley wave measurement;
using a wireline formation tester to perform downhole fluid analysis in the rock formation wherein the wireline formation tester pumps a flushed zone fluid from a flushed zone surrounding a borehole traversing the rock formation into the borehole and the wireline formation tester records pressure with time in the borehole during the downhole fluid analysis;
using one or more computer processor units to determine a wireline formation tester (WFT) downhole fluid analysis (DFA) mobility from integration of the pressure with time recorded by the wireline formation tester; and
using one or more computer processor units to determine a viscosity of the fluid by calculating a difference between the Stoneley mobility and the wireline formation tester (WFT) downhole fluid analysis (DFA) mobility or a ratio of the Stoneley mobility to the wireline formation tester (WFT) downhole fluid analysis (DFA) mobility.

2. The method according to claim 1 , wherein the ratio of the Stoneley mobility to the wireline formation tester (WFT) downhole fluid analysis (DFA) mobility is further multiplied by a viscosity of mud-filtrate within the rock formation.

3. The method according to claim 1 , wherein the rock formation comprises a carbonate rock formation.

4. The method according to claim 1 , wherein the viscosity of the fluid in the rock formation is determined for oil in a virgin zone surrounding the flushed zone.

5. The method according to claim 1 , further comprising comparing the Stoneley mobility and the wireline formation tester downhole formation analysis mobility and differentiating pay zone from wet zone in the rock formation if there is a difference between the Stoneley mobility and the wireline formation tester downhole formation analysis mobility.

6. The method according to claim 1 , further comprising using the viscosity to estimate and forecast production of recoverable and commercially developable hydrocarbons in the rock formation.

7. The method according to claim 1 , wherein the viscosity is determined without the use of lab measurements of oil samples obtained by a wireline formation tester or nuclear magnetic resonance data.

8. A system of determining a viscosity of a fluid in a rock formation, the system comprising:
a sonic logging tool configured to perform a Stoneley wave measurement in a rock formation containing a fluid;
a wireline formation tester configured to pump a flushed zone fluid from a flushed zone surrounding a borehole traversing the rock formation into the borehole and measure varying pressure with time in the borehole during a downhole fluid analysis; and
a computer system comprising one or more computer processor units configured to:
determine a Stoneley mobility by inversion using Stoneley complex phase velocity equations and the Stoneley wave measurement;
determine a wireline formation tester (WFT) downhole fluid analysis (DFA) mobility from integration of the varying pressure with time measured by the wireline formation tester; and
determine a viscosity of the fluid by calculating a difference between the Stoneley mobility and the wireline formation tester (WFT) downhole fluid analysis (DFA) mobility or a ratio of the Stoneley mobility to the wireline formation tester (WFT) downhole fluid analysis (DFA) mobility.

9. The system according to claim 8 , wherein the ratio of the Stoneley mobility to the wireline formation tester (WFT) downhole fluid analysis (DFA) mobility is further multiplied by a viscosity of mud-filtrate within the rock formation.

10. The system according to claim 8 , wherein the computer system is further configured to compare the Stoneley mobility and the wireline formation tester downhole formation analysis mobility and to differentiate a pay zone from a wet zone in the rock formation if there is a difference between the Stoneley mobility and the wireline formation tester downhole formation analysis mobility.

Assignees

• Chevron Usa Inc

Inventors

• Liu Chengbing
• Newton Stephen

Classifications

• E21B49/0875

  determining specific fluid parameters · CPC title

• E21B49/08

  Obtaining fluid samples or testing fluids, in boreholes or wells · CPC title

• G01N33/2823 Primary

  Raw oil, drilling fluid or polyphasic mixtures · CPC title

• G01N11/02

  by measuring flow of the material · CPC title

• G01N2011/0073

  acoustic properties · CPC title