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METHOD FOR DETERMINING VOLUME OF MUD FILTRATE PENETRATED INTO FORMATION USING CALIPER DATA

IP.com Disclosure Number: IPCOM000173596D
Publication Date: 2008-Aug-15
Document File: 4 page(s) / 57K

Publishing Venue

The IP.com Prior Art Database

Abstract

Physical properties of near-wellbore zone change during drilling and other jobs in the well. Due to pressure overbalance while drilling,formation fluids in a near-wellbore zone are displaced by drilling mud filtrate, which leads to the creation of invaded zone. The dynamics of this invasion is controlled by the formation of mudcake on the surface of borehole wall and the volume of mud filtrate penetrated into the formation. Due to different mobility of oil and water invasion zone has complex structure. It can be divided into the flushed zone (containing only mud filtrate having constant salinity) and low-resistivity zone – transition zone (as a rule, with increased content of mineralized formation water) in oil and water saturated reservoirs. We have developed the methodology to determine the parameters of invasion zone, such as saturation profiles, invasion depth, and total volume of mud filtrate penetrated into formation. The latter can be determined by using the data of caliper measurements, which provides the thickness of the mudcake, which, in turn, is directly related to the total volume of mud filtrate penetrated into reservoir. This invention presents the methodology based on a one dimensional axisymmetric model of formation fluids displacement. The model was developed based on the following: 1) the displacement of formation fluids by mud filtrate is described by Buckley-Leverett model; 2) elastic formation properties are taken into account via variable distance between the borehole wall and virgin part of the formation. We have carried out a series of numerical calculations for the developed model. It was concluded that calculated mudcake thickness for layers with different petrophysical properties conforms best to experimental caliper data and result of hydrodynamic inversion.

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Record Number: 2407 Invention Infoview Form

A. INVENTION OVERVIEW

BHI File Number: Division/Business Unit:

584-46415-US BAKER ATLAS


Division Technology/Product Line:
BA - GEOSCIENCE GROUP
Title of Invention:
METHOD FOR DETERMINING VOLUME OF MUD FILTRATE PENETRATED INTO FORMATION USING CALIPER DATA Abstract of the Invention:
Physical properties of near-wellbore zone change during drilling and other jobs in the well. Due to pressure overbalance while drilling,

formation fluids in a near-wellbore zone are displaced by drilling mud filtrate, which leads to the creation of invaded zone. The dynamics of

this invasion is controlled by the formation of mudcake on the surface of borehole wall and the volume of mud filtrate penetrated into the

formation. Due to different mobility of oil and water invasion zone has complex structure. It can be divided into the flushed zone (containing

only mud filtrate having constant salinity) and low-resistivity zone - transition zone (as a rule, with increased content of mineralized formation

water) in oil and water saturated reservoirs. We have developed the methodology to determine the parameters of invasion zone, such as

saturation profiles, invasion depth, and total volume of mud filtrate penetrated into formation. The latter can be determined by using the data

of caliper measurements, which provides the thickness of the mudcake, which, in turn, is directly related to the total volume of mud filtrate

penetrated into reservoir. This invention presents the methodology based on a one dimensional axisymmetric model of formation fluids

displacement. The model was developed based on the following: 1) the displacement of formation fluids by mud filtrate is described by

Buckley-Leverett model; 2) elastic formation properties are taken into account via variable distance between the borehole wall and virgin part

of the formation. We have carried out a series of numerical calculations for the developed model. It was concluded that calculated mudcake

thickness for layers with different petrophysical properties conforms best to experimental caliper data and result of hydrodynamic inversion. Product/Service Name (if known):
Hydrodynamoc modeling of invaded zone

B. THE INVENTOR(S)

FirstName LastName MiddleName CostCenter EmployeeNumber WorkEmail Status

Aleksandr Kashevarov A 410200601 00102593 Aleksandr.Kashevarov@bakeratlas.com Approved

Igor Eltsov N 410200601 00101000 Igor.Eltsov@bakeratlas.com Approved

Alexander Makarov I 00100984 AlexanderI.Makarov@bakeratlas.com Approved

Non BHI Employee Inventor(s):

C. CONCEPTION, CONSTRUCTION, AND OWNERSHIP OF INVENTION:

1. When did you first conceive the invention?

Date: 07/11/2005

2. Have you described the invention to someone else (internally or externally)? YES

Date: 04/12/2006

To Whom: conferantion

3. When did you make the first written description (today or earlier)?

Date: 06/07/2006

Location of Description: Russia, Novosibi...