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Supercharging Assessment in Formation Pressure Measurements Made While

Drilling by Deliberately Pulsed Circulation in a Carbonate Reservoir

Conference Paper · January 2017

DOI: 10.2118/187987-MS

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 SPWLA 57th Annual Logging Symposium, June 25-29, 2016

SUPERCHARGING ASSESSMENT IN FORMATION PRESSURE

MEASUREMENTS MADE WHILE DRILLING BY DELIBERATELY
PULSED CIRCULATION IN A CARBONATE RESERVOIR
Adil G. Ceyhan, Maria Bravo, Schlumberger, Kenny Walrond University of Stavanger

Copyright 2016, held jointly by the Society of Petrophysicists and Well Log horizontal section drilled in to the chalk reservoir.
Analysts (SPWLA) and the submitting authors.
This paper was prepared for presentation at the SPWLA 57th Annual Logging Pressure tests were evenly distributed to evaluate
Symposium held in Reykjavik, Iceland June 25-29, 2016. possible faults, depletion, and pressure barriers, and,
more importantly, to calibrate the flow model for the
ABSTRACT future drilling campaigns. Manipulating drilling fluid
circulation rates provided a series of deliberately
Forward modelling was applied to correct formation influenced tests as per the pre job modelling at a given
pressures measured while drilling on a wiper run for the depth. Three tests acquired at same depth interval with
effects of supercharging. Supercharging is increased different circulation rates were used as primary the
sand face pressure caused by drilling fluid filtrate leak- calibration point for the forward model calibration. A
off. The study is carried on one of the well-known secondary calibration point was obtained by from two
carbonate reservoir of the North Sea. This reservoirs, in consecutive tests, during which first circulation was kept
general, exhibit good porosity; however they have poor off, and then turned on. Over 300 numerical iterations
permeability because of small pores. This study was were carried out during the modelling process. These
unique in considering deliberately altered wellbore simulations are also applicable to exploring system
conditions based on pre-job modelling. behavior and responses when planning and executing the
job, assessing the feasibility and suitability of the
Pressure variations near the wellbore are primarily methodology to check that assumptions are satisfied, and
influenced by near-wellbore drilling fluid filtrate building some expectations about the likely measured
invasion and filter-cake formation. In general, the lower pressures and their behavior over time.
the sand-face permeability, the higher the variations.
Considerable progress has been made towards
understanding how filter cake forms and how it INTRODUCTION
influences the near-wellbore pressure stability.
Available analytical and numerical models in generally It has been long recognized that supercharging is one of
focus on dealing with “initial spurt loss” only, the the key fact geoscientists will live with for low
transition time to the dynamic period, and the dynamic permeability formations. Low permeability formation
period itself are assumed to be negligible. Recent studies in general described within the range of 5 to 10 mD.
suggest the transition time is complex, and it is not well Since WFT (Wireline Formation Testing) and FPWD
understood. However the dynamic period, which (Formation Pressure While Drilling) tools only
incorporates possible erosion, plastering, clogging, and measures mobility which is a function of viscosity of the
other implications, can be modelled if the sand-face mud filtrate, assuming 0.5 to 0.7 cP mud-filtrate
(near-wellbore) is exposed to controllable and viscosity this translate in to 10 to 20 mD/cP. Historical
quantifiable influences. The greater number of planned supercharging publications either heavily involved with
quantifiable influences, the better the forward modelling mathematical modelling or stayed tune solely into
and calibration for the sand-face will be. The coupled practical way to estimate the level of pressure elevation
filter cake growth and formation pressure model caused by supercharging.
incorporates; the geometry of the well and the drilling
assembly, the time sequence of the drilling or wiper One of the very early study (R. Parkes, A. Carnegie, T.
operation, and drilling fluid and formation properties. Neville, and S. Hookway) introduced “Step Over
Balance Method”. Key objective of this study was to
A total of 56 formation pressures were acquired in two change the hydrostatic pressure in an incremental rate
different wellbore, across several thousands of while measuring sand-face pressure by WFT. It showed
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SPWLA 57th Annual Logging Symposium, June 25-29, 2016

to be effective to evaluate the effect of overbalance to conduct test with same circulation rate, if not pumps
change over sand-face pressure, however it required off can be conducted, and further test with a higher
additional rig equipment to pressurize the annulus and it circulation rate.
also needed to accommodate safety precautions at the
well site. So it has not been utilized in large extend, but Aim of mathematical governing a software tool
it had proved the effect of changing overbalance on published by (R. Banerjee, R.K.M. Thambynayagam,
sand-face pressure measurement. and J. Spath) modelled the pressure response of a WFT
in a reservoir subjected to fluid invasion. They have
Another extensive study (A. K. Sarkar, J. Lee, E. Kasap) validated their model against numerical simulation
involved WFT in OBM (Oil Base Mud), low model. Although the model’s aim was to produce
permeability formations, and leaky mud-cakes. They reservoir horizontal and vertical permeability, well
have developed simple procedure for estimating mud- productivity index by using reliable inversion results
cake permeability and the supercharge pressure. Study within a timeframe suitable for correcting pressure
specified “Supercharge pressure is shown to be a during drilling process, however it did not focus on
product of apparent overbalance pressure, the mud- drilling practices, and insitu circulation effects on mud-
cake-to-formation permeability ratio, and an invasion cake properties.
factor representing the distance up to which
supercharging extends. The methodology requires good One of the recent publication (Zaher A., Sirju C)
knowledge of invasion factor, which involves time lapse developed IMPES modelling to incorporate two-phase
resistivity surveying, and this is not very practically with immiscible radial flow coupled with mud-cake growth
wireline logging. to consider only static filtration behavior. Model also
included gravity terms. Study concluded the most
One of the earlier study (J. Wu, M. Meister, B. Li) influential parameters for supercharging with its ranking
developed a coupled analytical method for mud cake from the highest as follows; (1) Permeability, (2) Mud
growth and formation interaction. Methodology Viscosity, (3) Overbalance, (4) Porosity, (5) Fluid
considered inverted five model parameters including; viscosity, and (6) Invasion Time. The Study
initial formation pressure, compaction factor, mud-cake demonstrated the effects of capillary pressure and rock
permeability, mud-cake thickness at the time before wettability on wireline formation testing.
testing, and skin (as internal mud-cake). They showed
based on field cases that estimated initial formation The study, we have presented here, integrates all
pressure agrees with time-lapse measurements, if a possible uncertainties and focuses on minimizing
proper exponent in the mud-cake growth model is assumptions by measuring several parameters at in-situ
selected. conditions. FPWD acquisition program tailored such a
way that deliberately pulsed sand-face properties
The later study (J.J. Pop, H. Laastad, K. O. Eriksen, M. measured spatially and timely distributed according to
O’Keefe, J. M. Follini, T. Dahle) introduced the the plan.
operational aspect of FPWD, as well as presented the
field test results of the recently introduced FPWD tool. Lately the methodology has been published by (Y. C.
One of the key result was also on evaluating Chang, P. S. Hammond, and J.J. Pop), (P. S. Hammond,
Supercharging. Interesting attempt made is to group the J.J Pop) has found practical ground to be applied in the
data according drilling practices, and what was field. The approached became the main ground of our
evidently clear that there was no strong correlation with study. Critical comments from the study that wrong
circulation rate within a particular well grouping, expect superstition on supercharging pressures decaying with
that clear benefit to perform FPWD test with pumps off. time. This is usually the case at wireline time, when
They also exhibited that depending on the quality of the drilling fluid circulation has ceased, a static mud-cake is
mud system and the drilling practices employed still growing, and filtrate- leak off rates are declining.
very good measurements were taken while circulating Studied simulation proved that this not the case while
at stations having mobilities between 0.3 to 0.9 mD/cP. drilling. Coupled simulations of filtrate leak off and
Finally, they have suggested; (1) it is not always safe to formation pressure have shown that supercharging
assume that the supercharging effect decrease with time levels can vary significantly as a well is drilled. The
after drilling, (2) pumps off tests halved the amount of prediction of supercharging while drilling and its
supercharging mobilities lower than 2 mD/cP, and (3) to variation with time requires a simulation framework
investigate sensitivity to supercharging, it is beneficial within which full history of fluid circulation and drilling
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 SPWLA 57th Annual Logging Symposium, June 25-29, 2016

operations can be captured. Pre-operation sensitivities drilling pressure taught to be required before entering
needed to be conducted to be able to achieve successive Reservoir B (which is expected to have low pressure) to
postmortem analysis. In this case study, several minimize drilling risks. Data quality and drilling risks
consideration is being made to appraise; BHA (Bottom had to be balanced during execution phase.
Hole Assembly) configuration, near horizontal wellbore Henceforward, in the real-operation will be discussed
buildup angle before entering the reservoir, pressure below, increasing time after drilling will greatly helped
transmission in Reservoir A, and effect of commination to minimize supercharging based on valuable sensitivity
between Reservoir A and B, effect of main fault on studies.
pressure. Hundreds of sensitivity runs being conducted
prior to applying methodology to the field case. These EXECUTION PHASE
simulations allowed to explore likely system behavior
and responses when planning the job, to assess the In-situ calibrated mud cake parameters was the key step
feasibility and suitability of the methodology, to check to determine actual sand-face pressure response after,
that assumptions upon which it is based are likely to be flow circulation rate intentionally induced. This is also
satisfied, and to build expectation about likely measured used for forward model match on hydraulic responses to
pressures and their behavior over time. reproduce the pressure disturbance after updating mud
parameters. Firstly three pretests were taken at same
PLANNING PHASE depth at three different mud circulation rates. This is
used as primary constrain for forward modelling; (1)
The case study carried out in the carbonates known to “wellbore hydraulic calculation”, and (2) “optimizing
have “High porosity, however low matrix permeability”. coupled filter-cake growth” on sand-face pressure.
Porosity could be as high as 45 Pu, however expected
permeability is around 0.2 to 3.0 mD . Figure 1 plots the Second constrain was applied to further improve the
case study wellbore, and its expected static and dynamic confidence was consist of acquiring two tests at the same
status. depth; one with nominal circulation rate, and second was
without circulation (inferring the static WFT) condition.
The modelling methodology used to simulate
supercharging has been published and details can be The followed calibration then required matching the
found in the literature (P. S. Hammond, J.J Pop). The modelled pressure response to the measurement one. In-
purpose of supercharging simulator is to; (1) design and situ mud parameter model created based on first
evaluate various measurement scenarios, (2) provide a constrains tests group, is then applied onto the second
qualitative or possible quantitative assessment on the constrain tests, and adjusted until all the responses fit
uncertainty of the pressure measurement in response to with the model. Figure 7 summarizes the workflow.
the drilling environment, (3) help to design and verify the Figure 8 and 9 displays the time-depth curve details for
interpretation of supercharging. Figure 2 exhibits the the Well # 1 and 2 respectively. Around 250 hrs of
workflow and required inputs for the modelling. progress has been considered for calculations.

Input parameters used for the forward modelling Over 300 numerical iterations were carried out during
presented in Table 1. Planning phase considered several the modelling process to infer the 56 measured test
possible sceneries while drilling, and the aim was to responses at given time and space. Key workflow steps;
capture and minimize uncertainties for the post run
analysis. Figure 3 exhibits the additional operational 1. Define initial estimate of the formation
parameters which goes in to the modelling to produce pressure,
sensitivities against Time after Drilling (TAD), and 2. Introduce mud parameters from planning
Dynamic Circulation. One of the typical sensitivity run phase and offset wells,
result can be seen at Figure 4. Figure 5 combined 3. Apply pressure perturbation while measuring
display of sensitivity analysis for time and circulation sand-face pressure,
rate effect on the tests. 4. Check annular hydraulic/pressure model and
compare with simulated one (first iteration
Figure 6 displays the pre-made typical flow chart for loop that needs to be close before continuing),
decision making during real-time while drilling and 5. Run simulation and compare final stabilized
testing. After reviewing what is achievable soon after pressure, if not match, redefine in-situ mud
drilling, operational details has laid down. Early after parameters to estimate formation pressure,
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SPWLA 57th Annual Logging Symposium, June 25-29, 2016

6. Compare modelled pressure with second set between the tools and the borehole, it was easy to deduce
of in-situ measurements, that either a turbulent or linear flow model could produce
7. Determine supercharging level. Figure 10 a good fit. Subsequently a linear flow model was applied
through 14 emphasis the each key steps. with few adjustments to the first well and the model
fitted very well the calibration points for the second well.
Therefore it is a fair assumption to use same hydraulic
Figure 10 zooms in to time during in-situ calibration tests
model for different wells providing that mud and
with different circulation rates. Corresponding forward
formation properties are alike.
model match for sand-face pressure vs time is shown at
Figure 11. Figure 12 and 13 exhibits the simulated test
CONCLUSION
and real-measured test at given depth respectively.
Figure 14 is the final in-situ calibrated and secondary
Values for the true far field formation pressure can be
constrained with pumps on and off test sand face
obtained from sand-face measurements via FPWD tool.
pressure for additional tests performed. The figure
The method requires some changes to normal drilling
models both sand-face pressure as well as dynamic
operations, but these are limited to, for example, changes
filtration change over time.
in the fluid circulation rate lasting for only minutes, at
most, while the formation pressure data is being
POST RUN ANALYSIS AND LESSON LEARNT
collected.
Post run sensitivities indicated impact of “Time after
Drilling” (TAD) reduces with increasing formation It was very helpful to use the “Forward Model” to
permeability. It was found that if TAD increases beyond simulate the filtration process and sand-face pressure,
6 hours, supercharging becomes half of the very soon both when planning and when performing the
after drilling under investigated conditions. It is believed interpretation. Modelling process has carried out with
that this was due to the effect of ongoing filtration and over 300 simulations runs. These simulations allow the
filter-cake building up. user to explore likely system behavior and responses
when planning the job, to assess the feasibility and
Investigated kv/kh sensitivity became negligible for the suitability of the methodology to check that assumptions
given formation environment of 0.5 to 7 mD/cP. satisfied, and to build some expectation about likely
measured pressures and their behavior over time. The
The results represent the relationship between more that is known about the filtration properties of the
supercharging and mobility (Figure 15). As expected drilling fluid, especially under dynamic conditions, the
lower the mobility the higher the supercharging more accurate these simulations and the better the testing
elevation. This is due to the fact that the low sequence can be designed.
permeability slows down the filtration process, and
increasing the fluid pressure on the sand-face that is The most important step on the model is the formation
translate into supercharging pressure calibration using the three pretests at three
different rates. Having a second point for calibration
Additional discussion might be useful to understand the
with a combination of two pretests with pumps on/off
outliers in Figure 15. The most bottom points in the
helped to confirm the validity of the model. Measured
green circle are pressure points taken with pumps off,
observations of sand-face pressure transients in response
hence supercharging amount is reduced due to the
to changes in the wellbore pressure are consistent with
absence of dynamic circulation. The pressure point on
the prediction of the model for compactable filter-cake
the top of the trend line are pressure points taken with
behavior.
early time after drilling compare to the other test taken
around similar mobility later in drilling. Note that these
Similar formation types can be group within the same
pressure points (in the red circle) were taken with a time
model if mud type and properties are kept similar.
after drilling under 15 hours, while the rest pressure
points are analyzed with a time after drilling of over 100
Time after drilling is an important parameter to drive the
hours.
pressure testing acquisition in LWD and to guarantee the
dissipation and equilibrium of the sand-face pressure
Initially a turbulent flow model was applied to account
after mud cake has formed. We believe that capability
for the mud circulation around the toolstring.
to simulate filtrate leak-off and formation pressures in
Considering that there is diverted loop of about 3in
details is a valuable aid in planning, understanding and
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 SPWLA 57th Annual Logging Symposium, June 25-29, 2016

interpreting formation pressured while drilling or after SPE ATCE held in Anaheim, California, USA 11-14
drilling. November 2007.
P. S. Hammond, J.J Pop. 2005. Correcting
Supercharging in Formation-Pressure Measurements
ACKNOWLEDGMENTS Made While Drilling. SPE 95710. Presented at SPE
ATCE held in Dallas, 2005.
The authors would like to thank Schlumberger for
R. Parkes, A. Carnegie, T. Neville, S. Hookway. 1998.
allowing the opportunity to publish this paper. Thanks
New Technique in Wireline Formation Testing in Tight
are also due to Simon Benard, Tony Quintal and Karl
Reservoirs. SPE 50128, presented at Perth, SPE Asia
Adam for help on the execution of the work.
Pacific OGC&E
R. Banerjee, R.K.M. Thambynayagam, J. Spath. A
NOMENCLATURE method for Analysis of Pressure Response with a
Formation Tester Influenced by Supercharging. SPE
BHA: Bottom Hole Assembly 102413 presented at Russian Oil and Gas Technical
Conference and Exhibition held in Moscow, 3-6 October
FPWD: Formation Pressure While Drilling
2006.
WFT: Wireline Formation Tester
Y. C. Chang, P. S. Hammond, J.J. Pop, 2008. When
TAD: Time After Drilling should we worry about Supercharging in Formation
Pressure While Drilling Measurements? SPE 92380,
published SPE Reservoir Evaluation & Engineering Feb,
2008.
SI METRIC CONVERSION FACTOR
Zaher A., Sirju C. Quantifying the Effects of Rock and
cP x 1.0 E+00 = mPas Fluid Properties on Point Probe Formation Pressure
Measurements. SPWLA paper presented at 55 th Annual
degF (F-32)/1.8 E+00 =K
Logging Symposium held in Abu Dhabi, UAE May 18-
ft x 0.3048 E+00 =m 22, 2014.
g/cm3 x 1.0 E+03 = kg/m3
gpm x 6.309 E-05 = m3/s
ABOUT THE AUTHORS
in x 2.54 E-02 =m
Adil G. Ceyhan is a Schlumberger Senior Reservoir
psi x 6.894757 E+00 = kPa
Engineer, currently Regional
mD x 9.869233 E-10 = m2 Drilling & Measurements
Reservoir Domain based in
Al Khobar, Saudi Arabia
since Aug-2015. He has 18
REFERENCES
yrs. experience with
Schlumberger in Formation
A. K. Sarkar, J. Lee, E. Kasap. Adverse Effects of Poor
Testing and Sampling,
Mudcake Quality: A Supercharging and Fluid Sampling
Production logging and
Study. SPE 48958, published SPE Reservoir Eval. &
various cased-hole and open-
Eng. 3, June 2000.
hole measurements to
J.J. Pop, H. Laastad, K. O. Eriksen, M. O’Keefe, J. M. address well and near
Follini, T. Dahle. 2004 Operational Aspects of wellbore problems. He started his carrier as Wireline
Formation Pressure Measurements While Drilling. Field Support Engineer and worked in the field for a year
SPE/IADC 92494, presented at SPE/IADC 2004 held in then joined the Interpretation Development Group, and
Amsterdam. worked in various assignments in Oman, Dubai, Kuwait,
Angola, Congo, Eq. Guinea, Iran and the North-Sea
J. Wu, M. Meister, B. Li. New Method for
mainly in Formation testing and sampling. Mr. Ceyhan
Supercharging Estimation. SPE 110389, presented at
was previously based in Stavanger, Norway where he
5
SPWLA 57th Annual Logging Symposium, June 25-29, 2016

was involved within Drilling Group to support Denamark, Netherlands and Romania.
Formation Pressure and Sampling While Drilling
operation design, execution and field testing. Mr Ceyhan
has a Bachelor Science and Master of Science Degree in Kenny Walrond is a reservoir engineer currently
Petroleum Engineering both from Istanbul Technical working at the Smart Water
University, Turkey Lab (EOR) at University of
Stavanger. He earned a
Bachelors in petroleum
Maria Cecilia Bravo is a Sclumberger Senior reservoir engineering from
engineer, currently Drilling Universidad Central de
& Measurements Associate Venezuela, and a MSc
Reservoir Domain Champion degree in petroleum
for Norway and Denmark engineering form
since April-2015, where she Montanuniversitat Leoben.
is involved within the He worked for over 4 years
Drilling Group to support as Reservoir and Production
Formation Pressure and engineer with Schlumberger analyzing production logs,
Sampling While Drilling well testing data (PTA), and formation testing and
operations. She completed a sampling in Venezuela (East and West fields including
BSc degree in the Simon the Orinoco Belt), Trinidad & Tobago and the North
Bolivar Univerisity in Sea.
Venezuela and obtained
Master of Science Degree in Petroleum Engineering
from Heriot-Watt University in Scotland. She started in
Schlumberger in 2008 as an L/MWD Field Engineer then
joined the Reservoir Engineering Data Services team
supporting downhole pressure and fluid sampling
analysis for offshore operations in Norway, UK,

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 SPWLA 57th Annual Logging Symposium, June 25-29, 2016

Table 1. Forward modelling input parameters for sensitivities to design the operational flow chart.

Table 1a. Formation Parameters Table 1b. Planned Mud Rheology

Formation Parameters Unit Value Mud Rheology Column1

Pressure psia X100 Hydraulics Model Herschel-Bulkley Mud Model
Temperature degF 150 Input Data Fann Data
Porosity fraction 20 Mud Density, ppg 9.200
Viscosity cP 0.5 Mud Compresibility, 1/psi 3.22E-06
Horizontal Permeability mD 0.5 Consistency Index (K) 120.6
Vertical Permeability mD 0.05 Behavior Index (n) 0.780
Total Compresibility 1/psi 1.0E-05 Yield Point 4.210

Table 1c. Drilling Bottom Hole Assembly Table 1d. Lab measured expected Fann Data
Bottom Hole Assembly
Configuration Diameter, in Length, ft Mud Fann Data Column1
Bit 8.490 0.990 Fann 3 5
Collar 8.120 13.460 Fann 6 6
Collar 8.375 6.600 Fann 100 18
FPWD 8.250 31.000 Fann 200 27
Tool 6.890 24.689 Fann 300 38
Tool 8.250 25.190 Fann 600 60
Tool 6.750 14.990
Tool 6.750 59.990
Pipe 6.500 158.990
Pipe 6.500 35.330
Pipe 6.500 31.000
Pipe 6.620 XXXX

Trajectory

A
B
B Pressure
Curve

0 1000 Cross Section along Trajectory

Figure 1. Dynamic and Static setting for studied field.

7
SPWLA 57th Annual Logging Symposium, June 25-29, 2016

Figure 2. Software workflow to quantify supercharging.

Bit Depth
Mud Circulation Rate, gpm

Figure 3. Operational parameters for the forward modelling.

8
 SPWLA 57th Annual Logging Symposium, June 25-29, 2016

Figure 4. Typical run results indicate supercharging pressure fall-off to appraise operation details given
in Figure 3.

600

500
Supercharge pressure (psi)

400
Kh1 1mD,
PUMPS ON (300
pumps on, 300 gpm
GPM)
300
Kh0.3
0.3mD, pumps
PUMPS on, 300
ON (300 gpm
GPM)
200
Kh0.3
0.3mD, pumps
PUMPS OFF off

100
Kh0.15 mD,
0.015 pumps
PUMPS OFF off

0
0 2 4 6 8 10 12
Time, hrs

Figure 5. Sensitivity run results for expected formation parameter and mud circulation while taking test
soon after drilling. This values set the upper limit of expected supercharging for given condition.

9
SPWLA 57th Annual Logging Symposium, June 25-29, 2016

Drill 10 more meters

from depth of interest

Circulate for at least 6

hours
Correlation
log

Perform stick test 5

and 10 minutes (30
min?)

Perform test for low

mobility formation

NO,
Was REPEAT test with probe re-
good seal Inform duty orientated to
obtained person the lower quadrant (+/-10
? deg of straight down) [also
consider the LCM content]

>=2 mD/cp
Less than Test
YES, 100 psi Stable? YES
Mobility superchargin (Slope < Inform duty Valid Test,
3 person move to
? g
psi/min) next depth

> 0. 6mD/cp and

< 2 mD/cp Do PUMPS OFF longest
Less than 150 psi avaliable test
supercharging

> 0.3 mD/cp

Less than 290 psi
supercharging

< 0.3 mD/cp Inform duty

More than 290 psi person Move +/- 1 ft
supercharging

Figure 6. Typical flow chart made available for the execution phase during Real-Time operation.

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 SPWLA 57th Annual Logging Symposium, June 25-29, 2016

Figure 7. Near real-time workflow from real measurement to Supercharging determination.

Pr obe– Depth
Time Depth Curve
Plot
Bit Depth Probe Depth Formation Depth

00 Wiper Run
Starts Pressure Tests
2000

4000
4000

Reservoir
Bit Depth (ft)

6000
Entry
8000

10000

12000

14000
Well 1 Well TD
3/1/2015
3/1/2015
3/1/2015
3/1/2015
3/1/2015
3/1/2015
3/1/2015
3/1/2015
3/2/2015
3/2/2015
3/2/2015
3/2/2015
3/2/2015
3/2/2015
3/2/2015
10:15:00
10:31:48
10:46:12
3/2/2015
12:00:00
12:43:48
3/2/2015
3/3/2015
2:00:00
3/3/2015
3:48:00
4:13:12
4:39:00
8:24:00
9:04:48
3/3/2015
9:52:48
3/3/2015
3/3/2015
1:16:12
2:03:00
3:09:00
4:00:00
10:55:12
7:07:12
11:34:48
7:37:12
12:31:12
AM
1:48:00
PM
PM
PM
4:39:00
PM
PM
12:06:00
12:55:48
PM
PM
3:24:00
AM
AM
AM
5:31:12
AM
7:03:00
AM
AM
PM
PM
PMAM
AM
AM
AM
AM
16000
-200 -150 -100 -50 0 50
0 50 Time (hr) (ZeroTime=3/1/2015
100 150 12:00:00 200
AM) 250 hrs Time

Figure 8. Time-Depth curve taken in to consideration for Well # 1.

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SPWLA 57th Annual Logging Symposium, June 25-29, 2016

Time – Depth
Pr obe DepthCurve
Plot
Bit Depth Probe Depth Formation Depth

00
Pressure Tests
2000

4000
4000
6000 Reservoir
Bit Depth (ft)

Entry
8000

10000

12000

14000 Well TD

16000 Well 2
2/16/2015
2/16/2015
2/17/2015
2/17/2015
2/17/2015
2/17/2015
2/17/2015
2/17/2015
2/17/2015
6:27:00
2/17/2015
2/17/2015
11:14:24
2/18/2015
2/18/2015
2:37:12
6:39:00
9:16:12
2/16/2015
2/16/2015
2/16/2015
PM
1:20:24
4:35:24
5:07:12
5:25:12
5:43:12
PM
2/16/2015
7:02:24
11:27:00
11:50:24
AM
12:59:24
AM
1:17:24
AMPM
7:14:06
8:08:24
PM
PM
PM
10:37:12
PM
PM
3:46:12
4:07:12
AM AMAMAM
PM
18000
0 20 40 60 80 100 120 140 160 180 200
0 20 40 60 (hr) (ZeroTime=2/10/2015
Time 80 100 120 12:00:00
140 AM)
160 180 200 hrs Time

Figure 9. Time-Depth curve taken in to consideration for Well # 2.

Hydraulic
Mud Cir culationPlot
Rate Plot
X500
600
250
Borehole Pressure, psi

200
Mud Rate (gpm)

150 Test 3

100
Test 2
Test 1
50

00 3/1/2015 3:48:00 PM 3/1/2015 4:13:12 PM 3/1/2015 4:39:00 PM

Y500
15.6 15.8 16.0 16.2 16.4 16.6 16.8 17.0 17.2
Time (hr) (ZeroTime=3/1/2015 12:00:00 AM)
Figure 10. Circulation rate alteration vs modelled wellbore annular pressure while formation tests. Dashed
blue time reference are the test times in to corresponding circulation change. Iterations performed to match
the wellbore annular pressure with in-situ measured pressure for Well # 1 during calibration tests. Time
zero is the wiper run start for well #1.
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 SPWLA 57th Annual Logging Symposium, June 25-29, 2016

Figure 11. Modelled Sand-face pressure after first set of constrained tests. Formation pressure acquired
at times: 15.80, 16.21 and 16.55 hours after drilling, represented by the dotted vertical lines. The model
takes into consideration “filter cake growth”, “dynamic pipe movements”, and “dynamic wellbore
hydraulics”. Formation tests taken at incremental circulation rate of 435, 455, and 480 gpm (gallon per
minute) respectively measured as A, A+1.5, A+ 3.0 psi in-situ sand-face pressure elevation. Mobility of
the tests were 2.8, 3.2 and 4.0 mD/cP respectively at the same depth for well # 1. Time zero is wiper run
start.

Figure 12. Simulated formation test based on constrained model, after first set of in-situ test.
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SPWLA 57th Annual Logging Symposium, June 25-29, 2016

Figure 13. One of the in-situ measured formation test. Measurement used for model iteration to verify the
Figure 10 results.

Super Char ge Plot

Super Charge Pressure Overbalance
Mud Filtrate Rate
0.00050 600
550
0.00045
500
0.00040
Psf - Pf (psi), Overbalance (psi)

450
0.00035
Filtrate Rate (in3/s/in2)

400

0.00030 350
300
0.00025
250
0.00020 200

0.00015 150

0.00010
100 Well # 2
50
0.00005
0
2/16/2015
2/16/2015
2/16/2015
2/17/2015
2/17/2015
2/17/2015
2/17/2015
2/17/2015
3:46:12
2/17/2015
4:07:12
2/17/2015
6:27:00
2/17/2015
11:14:24
2/18/2015
2/18/2015
2:37:12
6:39:00
9:16:12
2/16/2015
PM
2/16/2015
1:20:24
PM
2/16/2015
4:35:24
5:07:12
5:25:12
5:43:12
PM
7:02:24
11:27:00
11:50:24
AM
12:59:24
1:17:24
AM
AMPM
PM
7:14:06
PM
8:08:24
PM
10:37:12
PM
AM AMAMAM
0 -50
20 40 60 80 100 120 140 160 180 200
Time (hr) (ZeroTime=2/10/2015 12:00:00 AM)
Figure 14. Modelled supercharging, dynamic filtration rate and overbalance change during the tests.
Vertical lines indicates the time of test timings.

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 SPWLA 57th Annual Logging Symposium, June 25-29, 2016

Figure 15. Modelled Supercharging vs. measured mobility.

15

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