US2014379265A1PendingUtilityA1
Real-time method for determining the porosity and water saturation of an underground formation using gas and mud logging data
Est. expiryOct 24, 2031(~5.2 yrs left)· nominal 20-yr term from priority
E21B 49/003G01V 1/50
12
PatentIndex Score
0
Cited by
0
References
0
Claims
Abstract
Real-time method for determining the porosity and water saturation of an underground formation using gas and mud logging data A method and a computer program product for determining the porosity (PHI) and water saturation (Sw) of an underground formation while drilling a borehole, using gas and mud logging data obtained while drilling.
Claims
exact text as granted — not AI-modified1 . A method of determining the porosity (PHI) and water saturation (Sw) of an underground formation while drilling a borehole, which comprises:
I. calculating the Perforability Index (PI) as the inverse of the Rate of Penetration (ROP) normalized which is solved as the mathematical correction of the mud logging parameters obtained while drilling that affect the Rate of Penetration (ROP); II. normalizing the methane (C1) data as a mathematical correction for variation in drilling parameters III. plotting the methane (C1) normalized data versus Perforability Index (PI) in a double logarithmic plot; and the Perforability Index (PI) versus depth in linear scale; IV. using the plots above to determine
i. the Gw baseline representing the 100% Sw;
ii. the PI 0line representing the line in shale or zone with 0% porosity;
V. determining the Sw_Gas from the determined Gw baseline obtained in step IV and determining the porosity using E-log data of a reference well (PHI_LOG) or from the determined PI 0line obtained in step IV when no reference well is available (PHI_ML).
2 . The method according to claim 1 , wherein in step I the Perforability Index (PI) is calculated from the equation 1
PI
=
1
[
Log
ROP
RPM
Log
3
·
WOB
14
·
BS
]
wherein ROP is the Rate of Penetration, RPM is the Revolutions per Minute, WOB is the Weight on Bit, BS is the Bit Size; and the mud logging data are obtained while drilling.
3 . The method according to claim 1 , wherein in step II the normalization of the C1 data is calculated from the equation 2
C
1
Norm
=
11.6
·
C
1
·
FLOW
ROP
·
(
BS
)
2
wherein C1 is methane, FLOW is the Flow in, ROP is the Rate of Penetration and BS is the Bit Size; and the gas and mud logging data are obtained while drilling.
4 . The method according to claim 1 , wherein the Gw baseline is a linear line passing throught the topmost data points of shale and water zone on the double logarithmic plot of the C1 normalized data vs Perforability Index (PI).
5 . The method according to claim 1 , wherein the determination of the water saturation (Sw) using the Gw baseline step is calculated from the equation 3
Sw_Gas
=
Gw
Gh
wherein Gh, are the C1 normalized values for each depth points of the borehole
6 . The method according to claim 1 , wherein the determination of the porosity is carried out using E-log data of a reference well (PHI_LOG) or without any reference well data (PHI_ML).
7 . The method according to claim 6 , wherein the determination of the porosity (PHI_LOG) is carried out using E-log data of a reference well by derivation of the correlation between PHI and PI plotting in linear scale the PI versus total porosity obtained from E-log data in a calibration well.
8 . The method according to any of the claims 6 - 7 , wherein the estimation of the PHI_LOG is obtained using the Reduced Major Axis (RMA) regression formula derived by plotting, in linear scale the PI versus the Total Porosity obtained from Density/Neutron Log data (PHINDX) of the reference well.
9 . The method according to claim 6 , wherein the determination of the porosity (PHI_ML) is carried out without any reference well data, and is calculated by plotting, in a linear scale, the PI versus the depth to define a PI baseline in shale or zone with 0% porosity (PI 0line ); and deriving the PHI_ML from the equation 4
PHI_ML
=
{
{
PI
-
PI
0
line
PI
0
line
}
+
K
}
M
wherein
PI=Perforability Index;
PI 0line =PI baseline in shale or zone with 0% porosity; and
0.2<K<1, and 0.05<M<0.5
10 . A computer program product comprising program instructions for causing a computer to perform the method as defined in claim 1 .
11 . The computer program product according to claim 10 , embodied on a storage medium.
12 . (canceled)
13 . A system of determining the porosity (PHI) and water saturation (Sw) of an underground formation while drilling a borehole, the system characterized in that comprises computing means for calculating the Perforability Index (PI) as the inverse of the Rate of Penetration (ROP) normalized which is solved as the mathematical correction of the mud logging parameters obtained while drilling that affect the Rate of Penetration (ROP), using the mud logging data Rate of Penetration (ROP), Revolution per Minute (RPM), and Weight on Bit (WOB) obtained while drilling; computing means for normalizing the C1 data as the mathematical correction of the mud logging parameters that affect gas shows; computing means for plotting the C1 normalized data versus Perforability Index (PI) in a log log cross plot; and the PI versus depth in linear scale; computing means for using the plots above to determine the Gw baseline representing the 100% Sw and the PI baseline in shale or zone with 0% porosity; and computing means for determining the porosity and water saturation using the Gw baseline or the Perforability Index baseline (PI 0line ) obtained above.
14 . A system of determining the porosity (PHI) and water saturation (Sw) of an underground formation while drilling a borehole, the system comprising a memory and a processor, embodying instructions stored in the memory and executable by the processor, the instructions comprising functionality to:
I. calculating the perforability index (PI) as the inverse of the Rate of Penetration (ROP) normalized which is solved as the mathematical correction of the mud logging parameters obtained while drilling that affect the ROP; II. normalizing the methane C1 data as the mathematical correction for variation in drilling parameters II. plotting the C1 normalized data versus Perforability Index (PI) in a double logarithmic plot; and the PI versus depth in a linear scale; IV. using the plots above to determine
i. the Gw baseline representing the 100% Sw;
ii. the PI 0line representing the line in shale or zone with 0% porosity;
V. determining the Sw_Gas from the determined Gw baseline obtained in step IV and determining the porosity using Elog data of a reference well (PHI_LOG) or from the determined PI 0line obtained in step IV when no reference well is available (PHI_ML).
15 . Method for identifying and evaluating an underground formation of interest while drilling a borehole which comprises:
a) determining the porosity and water saturation obtained while drilling a borehole according to claim 1 ; b) determining the total amount of hydrocarbon in the reservoir from the equation
T =(1−Sw)PHI·Vt
wherein T is the Total amount of hydrocarbon, Sw and PHI are the water saturation and porosity taken over the entire reservoir, and Vt is the total volume of the reservoir.Join the waitlist — get patent alerts
Track US2014379265A1 — get alerts on status changes and closely related new filings.
We store only your email — no account needed. See our privacy policy.