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SPE-187661-MS
First Successful Intelligent Tracer ICD Completion - Horizontal Well Inflow
Profile PLT
Raju Mankala, Hamad Ahmad Al-Zaabi, M. A. Siddiqui, H. B. Chetri, and Abdullah Jafer Al-Mousawi, KOC
Copyright 2017, Society of Petroleum Engineers
This paper was prepared for presentation at the SPE Kuwait Oil & Gas Show and Conference held in Kuwait City, Kuwait, 15-18 October 2017.
This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents
of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect
any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written
consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may
not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright.
Abstract
North Kuwait Asset of Kuwait Oil Company is pursuing fast track technology deployment in its fields
to meet the challenging production targets. The horizontal wells provide best way to accelerate the
reservoir production through increased reservoir contact but it brings some inherent problems in optimizing
production and low cost well intervention. To address these inherent challenges, North Kuwait started the
deployment of inflow control device (ICD) has become a normal trend of completion in horizontal wells.
The completion of horizontal wells with ICDs helps in optimizing production but information of inflow
contribution from each section qualitatively and quantitatively is still a challenge. In this perspective, KOC
has deployed intelligent chemical inflow tracer technology combined with On/Off ICDs below an ESP in
a horizontal well located in its northern field to assess the inflow performance of the production. In these
long horizontal wells, traditional production logs are considered risky and expensive due to the limitations
of using a small-diameter coil tubing, which must fit through the Y-tool on the ESP. This small diameter
coil tubing will go into helical buckling before reaching the toe of the well resulting in an incomplete log for
the well. In some cases, the wells are lacking Y-Tool facility, which practically does not allow production
logging in the well.
In such cases, the intelligent chemical inflow tracers are used to provide a qualitative assessment of
the clean-up phase of production, quantitative inflow information from each zone, and to identify the
section producing water along the horizontal well. The use of intelligent tracers overcame the intervention
challenges by installing intelligent downhole chemical sensors in pup-joint carriers next to the ICD joints in
each compartment from heel to toe. Fluid samples collected from the surface flow lines were analyzed for
unique chemical tracer signatures and interpreted the corresponding tracer signals. This has resulted into
identification of quality of fluid flowing from each section concomitant with its quantification.
This paper discusses the first well installation of its kind in North Kuwait, the methodology for selecting
the technology, the deployment in the well, and the interpretation of results of water and oil tracers obtained
during different monitoring campaigns through fluid sampling.
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SPE-187661-MS
History & Background
The giant Mauddud reservoir in Sabriyah field of North Kuwait (NK) is the largest reservoir in NK and is
currently the focus for development activities. It is an elongated faulted anticline plunging to the north. Initial
development was in the crestal part where the best reservoir properties and fluid characteristics exist. Despite
long production history, the reservoir is still at a relatively early stage of development. Introducing water
injection for pressure support has been necessary at an early stage in the development process. Historical
reservoir information and results from water flood indicate that reservoir performance in these reservoirs is
controlled by geological complexity at several scales, with varying heterogeneity from the crest to the flanks.
Initial development was limited in the crestal part where the best reservoir properties and fluid
characteristics exist. SAMA vertical section is about 350-400 feet thick and broadly divided into ten
reservoir zones based on reservoir facies and major flow units identified. They are designated as Ma-A to
Ma-J from top to base. The majority of hydrocarbon pore volume and production is located in the upper
flow units from Ma-B to Ma-E. On the other hand, lower Mauddud (MaF to MaJ) is a tight reservoir. MaH
is clastic interval embedded in this sequence interpreted as outcome of reactivation of Burgan delta and
subsequent poisoning of carbonate shelf. MaD and MaE represents the high bank of carbonates.
Figure # 1—Type log of Mauddud formation in Sabriyah Field - SAMA
Typical Rock and Fluid properties average values:
SPE-187661-MS
3
Parameter
Low
High
Permeability, md
10
80
Porosity, %
10
22
Gross Thickness, ft
300
API gravity
18
32
Solution GOR, scf/bbl
50
600
Viscosity, CP
1.5
10
Productivity index
0.5
6
Injectivity index
0.5
8
Well Location & Trajectory
SA-0XXXH (MA) well was selected after detailed analysis in existing injection pattern location to match
with pilot requirement to test efficiency of both oil and water tracer evaluation and to assess the completion
efficiency in the shortest possible time period.
The ICD completion utilizing intelligent tracer technology to generate qualitative and quantitative inflow
profiles helps in identification of non-productive horizontal ICD compartments. This is a step change in the
surveillance and optimization of horizontal ICD completions in North Kuwait.
Figure # 2—Well location in Sabriyah Field – SAMA injection pattern
Key Deliverable and Basis of Tracer Design System
The key deliverable is the equivalent of a permanently installed downhole flowmeter or at a remote
analogy Production Logging through a logging tool. The technology is particularly suited to complex
well completions or long horizontal wells where alternative reservoir monitoring techniques are, risky,
logistically impossible or prohibitively expensive.
Analysis of the samples to yield tracer concentrations, typically in the parts per trillion range, is performed
in the laboratories of tracer provider. Interpretation addresses all phases in a well's life such as clean-up,
restart, steady production and water breakthrough. This can also provide zonal inflow contributions, like toe
to heel contributions from a horizontal well, either qualitatively or, in single-phase conditions, quantitatively.
The chemical Tracer technology was evaluated and a project with these tracer incorporated into inflow
control device (ICD) was initiated in North Kuwait to address the challenges of production monitoring in the
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SPE-187661-MS
horizontal wells completed with ICD. The inflow control devices are flow regulators installed downhole to
optimize production by maximizing sweep efficiency and avoiding bypassed oil. However, with the passage
of time, the reservoirs deplete and the production will not remain the same. Even the wells completed
with flow regulating completions produce water from the unexpected zones. Hence, the industry developed
advanced ICDs with sliding sleeves that enable an operator to isolate the watered out section mechanically.
Nevertheless, to identify the water producing sections the challenge is to run production logging, which is
not operator friendly in terms of operation, time and cost. Hence, the intelligent chemical tracer technology
was developed to counter the investigative challenges in horizontal wells. The tracer technology provides
almost real-time information without well intervention at justifiable cost. One of the pilot wells was selected
from North Kuwait Sabriyah field.
The agreed flow monitoring objectives for deploying tracer systems in the trial well in Sabriyah field
of North Kuwait were:
•
•
•
•
Clean-up evaluation during initial and restart flow back of the well
Locate water breakthrough intervals or sections
Estimate relative oil inflow
Monitoring of oil and water production during steady state
The release of tracer is triggered by the contact with target fluid phase: incoming water for water sensitive
tracer systems, and incoming oil for oil sensitive tracer systems. The tracer release varies with area of the
system that is exposed to the target fluid. The tracer release rate is however independent of the fluid velocity.
The main downhole and production parameters used for optimizing the tracer system design were:
Temperature: 180°F (at 8,100ft. TVD)
Completion and stimulation fluids:
– Completion fluid: OBM / WBM
– Wellbore clean-up fluid (Filter cake breaker)
– Completion brine in wellbore above the ICD
Shut-in period: Shut in ~15 days after drilling rig moves from the wellsite
•
•
•
•
•
•
Shut-in fluid: WBM
Oil Density (API): 32° API
Max commingled flow rates at sampling point (O/W/G): 2,000bopd / 500bwpd / 650scf/d
Tracer marking period: Tracer systems remain dormant until wetted by target fluid (oil or water)
and remain useful for:
Oil Tracer: 2 years (included shut-in time)
Water Tracer: 1 year (included shut-in time)
Tracer integration into Tracer Carrier
The oil and water tracer systems were installed in paired fashion in 4 −1/2" Tracer Carrier Subs manufactured
by KOC approved vendor. The 4.5" Tracer Carrier Subs accompanied by a screen section are outward
ventilated with carrier OD: 4.5" (114.3 mm) / ID: 3.958" (100.53 mm). Tracer rods or strips were installed
in the void between the OD of the base pipe and the ID of the perforated shroud evenly distributed around
the circumference of the base pipe.
SPE-187661-MS
5
Logs of Operations Events & Objectives
Date
Operation & Objecives
Results & Observation
25-Mar-16
Drilling completed up to 12155 Ft MD target depth
as per plan
Well Completed as per planned trajectory
31-Mar-16
12 segment of SS-ICD with Intelligent Tracer Joints
Well Completed as per planned intelligent Tracer ICD requirement
completion installed
4-Apr-16
15-Apr-16
17-Aug-16
ESP Function test Sample analysis
Well Clean-up and Completion efficiency is good; minimum at toe
section
ESP Re-start Sample analysis after flow line
connection GC23
All segments are contributing as per expectation; all Oil & Water
tracer are detected
Steady State Sample after well stabilisation
All segments are contributing as per expectation; all Oil & Water
tracer are detected
Well Completion
The selected pilot well is a horizontal well with a long production interval and the well was drilled with
water based mud as a 6-1/8" open hole passing through various layers of Mauddud reservoir in North Kuwait
Sabriyah field. The length of the horizontal leg is 4,610 ft, which was divided into 12 zones each separated
by swell packers. Each zone is completed with ICD screen joints with a tracer carrier
Tracer carrier systems containing tracer pairs (water + oil) were run in a hole next to each ICD screen
and numbered from 1 to 12 from toe to heel, respectively, as shown in Figure 3.
Figure 3—Pilot well completion schematics. The intelligent Chemical Tracer systems
are marked as unique colors and numbered from 1 to 12 from toe to heel accordingly.
Tracer Sampling and Analyses Program
It was planned to collect samples from the well for tracer analysis in produced fluid in three major stages,
which are described below:
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SPE-187661-MS
1. During well clean-up: Samples collected and analyzed in this phase to see the well clean-up
effectiveness
2. After restart of the well: The well after testing usually shut-in to wait for the connection of the well,
through laying of pipes, to gathering center (GC). The sampling was done in this phase for a week
until the signal of steady flow received.
3. During Steady state production of well: This is the stage where well flows steadily in a normal
production phase.
The first two stages are called as transient stages, while the last stage is called steady state. The stage
wise sample analyses is given in the following sections.
Well Clean-up (ESP Function Testing) Monitoring
The objectives for this campaign was to monitor the well clean-up through effective sampling of produced
fluids and their subsequent analysis for tracers. The visual analyses of the collected samples showed that
the first eight samples contained only water and mud. The crude oil appeared in the ninth sample. It was
noticed that, as the well was cleaned out, the oil production rate progressively increased.
Analyses results and Interpretation (Tracer response)
The analyses of the results were very much conclusive for this sampling campaign. Signals from all the
installed tracer systems were detected at high levels indicating that all zones contributed to well flow
(production). The tracer concentrations in the analyzed samples are shown in Figure 4. The detailed
interpretation (qualitative & quantitative) of the tracer responses is given in the following sections.
Figure 4—Measured oil and water tracer concentrations in the collected samples
Qualitative clean-up flow interpretation
High amplitude and rapid decline of the oil tracer transient curve indicate good contact of tracer system
with oil during shut-in, indicating the dominate oil phase inflow, at the zones corresponding to the tracer
locations. The acronyms OS and WS refers to "Oil System and Water Systems, respectively" and referred
to through this paper.
SPE-187661-MS
7
Analyses of samples from Toe section. The responses from the toe part of the well (Figure 5) are found
to be relatively weak. The oil tracer responses and delayed water tracer build-ups arrival from zones 1 to 4
may indicate the toe is poorly cleaned up and flooded with water and therefore the toe production is limited
(chocked back by the rest of the well). This behavior is normal for a horizontal well.
Figure 5—Oil and water tracer responses from toe section of the well on clean-up
Analyses of samples from Middle sections. Oil tracer responses were strong from OS-6, OS-5 and OS-9
indicating zone 6 to be the dominant oil inflow during the clean-up campaign. The clean-up of zones 5
and 9 was slightly delayed but still show good clean-up performance. In Figure 6, the oil and water tracer
responses from middle section of the well are shown, which describes that:
•
•
•
Sharp oil responses from zones 6, 5 and 9 indicate high oil inflow
Less sharp but smoother oil responses from zones 7 and 8 indicate lower oil inflow
Water tracer responses are similar and show efficient displacement of completion fluids
Figure 6—Oil and water tracer responses from middle section of the well on clean-up
Analyses of samples from Heel section. The heel section of the well has shown more water. High water
peaks with quick concentration drop from zones 10 to 12 may indicate the heel to have high water contact
8
SPE-187661-MS
during shut-in and fast shut-in fluid displacement on opening the well, Figure 7. This means that zones 10,
11 and 12 have been effectively cleaned up before any of the other zones in the well. Relatively low oil
tracer responses indicate the limited oil contact.
Figure 7—Oil and water tracer responses for the heel section of the well on clean-up.
At the end of clean-up period the sample analyses results showed that the production was very much
stable. The following conclusions can be drawn:
•
•
•
Stable expected steady state levels ensure completed clean-up in zones 5 to 12
Low levels of OS-1 and OS-2 indicate poor clean-up in zones 1 and 2 (Toe section)
Increasing trends of OS-3 and OS-4 indicate ongoing clean-up of zones 3 and 4
Quantitative Interpretation of Water and Oil Samples from clean-up stage
The quantification of the water and oil flowing from each zone was done using proprietary "Flushout model."
The basic principle of the "Flushout" model was discussed in SPE-167463. Based on this principle, the
quantitative interpretations for water production rate Qwater = 1200 bbl/d, and oil production rate Qoil =
480 bbl/d, which is measured with surface portable separator during ESP function testing are presented in
Figures 8 & 9, respectively.
Figure 8—Qualitative clean-up interpretation, showing degree of clean-up of sections
SPE-187661-MS
9
Figure 9—Quantitative clean-up interpretation
Well Restart Tracer Monitoring
The main monitoring objectives for this campaign were to provide a qualitative and quantitative
interpretation for well restart. The well was shut in for 10 days before the restart. A total 61 samples were
collected in this campaign. The first 14 samples have high water content with low salinity but increased over
time during the sampling campaign, indicating the back production of completion fluids. For this campaign
32 samples were analyzed for oil tracers and 19 for water tracers (51 in total). The well flow parameters
during restart were available hence no assumptions were required to be made during interpretation.
Qualitative and Quantitative fluids flow interpretation
Oil inflow profile is estimated using "Flushout" model based on restart responses. Assuming the oil
production rate during Re-start Qoil = 920 bbl/d, the measured PGOR rates during end of function test used
for the quantitative oil inflow profile estimation. The quality of the water tracer signals was not robust
enough to apply the "Flushout" model for water flow interpretation.
Conclusions for the Restart sample analyses summary
Figure 10—Qualitative conclusions summary for steady state monitoring campaign
10
SPE-187661-MS
Figure 11—Qualitative conclusions summary for steady state monitoring campaign
Steady State Monitoring
This monitoring corresponds the stage at which the well was set on production after the transient (cleaup
and restart) stages are completed. The monitoring objectives for this campaign was to detect tracer signals
and identify zones of initial water breakthrough and any subsequent breakthrough along different locations.
Production and sampling history
In total, 60 samples were collected together with production data. The well was on steady production with a
running ESP and no well interventions occurred within 48 hours, prior to the commencement of sampling.
During steady state sampling the well was producing with 45% water cut. For this campaign, 60 samples
were analyzed for oil tracers and 60 for water tracers (120 in total).
Conclusions on Steady state monitoring
Conclusions from the interpretation of tracer signals from steady state monitoring are summarized in Figure
12 and described below:
Figure 12—Qualitative conclusions summary for steady state monitoring campaign
Acknowledgment
The authors are thankful to Ministry of oil Kuwait for granting the permission to publish this paper. The
authors are equally indebted to KOC management for allowing and encouraging to publish this paper.
SPE-187661-MS
Acronyms
BP
CAR
DP
OS
PKR
SCN
WFT
WS
11
Blank pipe
Carrier (tracer carrier)
Drill pipe
Oil System or oil soluble system
Packer
Screen (ICD Screen joint)
Wet Float (shoe)
Water System or water-soluble system
References
1.
2.
3.
4.
H.B. Chetri, A.N. Khan, M.F. Al-Ajmi, S. Srivastava, E. Al-Anzi, and M. Al-Hajeri, M. KOC:
Paper SPE 78513 presented at the Abu Dhabi International Petroleum Exhibition and Conference,
13-16 October 2002, Abu Dhabi, United Arab Emirates.
Mohammed A. Siddiqui, KOC, SPE, Ahmad K. Al-Jasmi, KOC, SPE, Menwer M. Al-Rasheedi,
KOC, and Hashem F. Al-Abdullah, KOC Five Years Journey of Advanced Completions in KOC,
Paper SPE 175330 at the SPE Kuwait Oil & Gas Show and Conference held in Mishref, Kuwait,
11–14 October 2015.
Mankala Raju (KOC); Dalal Al-Sirri (KOC); Mohammad Harier Al-Husaini (KOC); Nasser AlHajeri (KOC); H B Chetri (KOC) and Hussain Al-Ajmi (KOC), Persistent Approach to Improve
Well Performance and Production Sustenance, Paper SPE 160634 at ADIPEC 11-14 November
2012
Unpublished reports, presentations & technical file notes/ FD(NK)/ KOC
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