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GEOPHYSICAL MONITORING OF THE OIL PRODUCTION AND CO2 GEOLOGICAL STORAGE

IN INTELLIGENT FIELDS

Paulo Camargo

Virgílio José Martins Ferreira Filho

Petroleum Engineering - POLI/COPPE Federal University of Rio de Janeiro UFRJ

P.O. Box 68548

Rua Moniz Aragão Nº 360, Bloco 2, Cidade Universitária

Rio de Janeiro, 21941-594, RJ

B R A Z I L

Phone: (+55 21) 3938-3537

Abstract

The first intelligent fields (also called i-fields, e-fields, smart fields, integrated operations, and

others) are being installed in the Brazil. So a great technical knowledge needs to be acquired for a

successful performance. The geophysical reservoir monitoring in intelligent fields is a whole new

field of research, where different geophysical techniques are being tested for their effectiveness in

the monitoring the oil production and geological storage of CO2. In this article we show the

techniques that we are researching in these two perspectives. So that geophysical techniques, such

as 4D seismic, 4D Microseismic Monitoring, Microgravity, Seismic permanent using Fiber Optic and

others are discussed. Moreover, some aspects of the future vision of intelligent fields such as

nanotechnology are introduced.

Keywords: 4D seismic, 4D Microseismic Monitoring, Microgravity, Seismic permanent using

Fiber Optic

MONITORAMENTO GEOFÍSICO DA PRODUÇÃO DE ÓLEO E ARMAZENAGEM GEOLÓGICA

DE CO2 EM CAMPOS INTELIGENTES

Resumo

Os primeiros campos inteligentes (também chamado de i-fields, e-fields, campos inteligentes,

operações integradas, e outros) estão sendo instalados no Brasil nos dias hoje. De maneira que

um grande conhecimento técnico precisa ser adquirido para um desempenho bem sucedido. O

monitoramento geofísico de reservatórios em campos inteligentes é um campo de pesquisa

totalmente novo, onde diferentes técnicas geofísicas estão sendo testadas para verificar a sua

eficácia no monitoramento da produção de petróleo e armazenamento geológico de CO2. Neste

artigo mostramos as técnicas que estamos pesquisando nestas duas perspectivas. De forma que

técnicas geofísicas, tais como Sísmica 4D, Monitoramento Microsísmico 4D, Microgravidade,

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Sísmica Permanente usando Fibra Ópticas e outros são discutidos. Além disso, alguns aspectos da

visão de futuro de campos inteligentes como a nanotecnologia são introduzidos.

Palavras chave: Monitoramento geofísico, Armazenamento geológico de CO2, Campos

Inteligentes.

1. Introduction

There is a consensus among high executives of the ecosystem oil/gas that the Technology

Progress will make a decisive role in the oil industry in the next 30 years. This fact has created the

interest in different companies by the development of Intelligent Fields. The geophysical reservoir

monitoring in these instrumented fields is a new research area, where a set the techniques are

being tested to verify its efficiency in the reservoir monitoring. These techniques can monitor the

reservoir in a variety of aspects. Two important aspects are oil production and CO2 storage. This

article begins showing the view of experts about the future of the oil fields. And the importance that

Intelligent Fields have in the future of the petroleum industry. Following we show some discussions

about these fields. Its advantages, associated technologies and the new technologies that in the

coming years will be incorporated. And with that is shown the role of geophysical monitoring within

the reality of Intelligent Fields. Finally we present the geophysical techniques that we are

researching. Our research is being conducted because, from our point of view in the Santos Basin

Pre-Salt, oil production operations and CO2 storage must be held within Smart Fields. Thus, oil

production, CO2 storage and Intelligent Fields have to be seen together.

2. A vision of the future

Recently in a series of articles published by the Center of Applied Insights IBM and IBM

Global Business Services (entitled Oil and Gas 2030, The Value of Smater Oil and Gas Field, and

others) is shown a study conducted among more than 100 high executives of the ecosystem oil/gas

around the world (Figure 1 shows the distribution of interviews by segments of the market) Edison

et al. [2011], Edwards et al. [2010]. The aim of this study was to understand the vision of the future

of these executives. Some very interesting information was obtained, for example, when asked

about the five external factors that impact nowadays more significantly their companies, 61% of the

executives responded that Technology Progress is the most important external factor. And when

asked about the future, that is, what external factors they consider will have greater impact on their

business in the coming decades, this number rises to 81%. This means that there is an almost

universal belief that Technology Progress will make a vital role in the oil industry in the coming

years. Figure 2 shows the results of this study.

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Figure 1: Interviews by market segment.

Another very important conclusion in this study is that the executives believe that Technology

Progress in the future will be more impactful for their companies than the Energy source availability

(see Figure 2). If we consider that in the future there will be a growing demand for energy, the

value of the Technology Progress increases in the future of the business. Literally, the conclusion

was the following: The challenge in the short term (30 years) is not the availability of new energy

sources, there is enough hydrocarbon resources in the world for the next century, but how to

develop existing sources efficiently and safely, having the technology as a key factor. There is a

consensus that the development of integrated operations involving technology, people and

processes creates opportunities to address the major challenges of the present and future of the oil

companies. This study has based investments of the IBM in the development of Integrated

Operations/Intelligent Fields.

Figure 2: External factors more significant in the view of future of the executives. Edwards et al.

(2010).

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3. Intelligent fields

The term Integrated Fields has received by different oil companies, different names, such as

I-fields, Smart Fields, Digital Oilfield, e-fields, Field of the Future. And they are undoubtedly the Oil

Fields of the Future, Al-Dhubaib (2011), Foss (2011). This fact has been admitted by a large

number of specialists. And the reason, are the great advantages that Intelligent Fields exhibit in

relation to conventional fields (Figure 3 shows a schematic representation of an Intelligent Field).

Below are listed some of these advantages:

• Obtaining high-quality information in real time of the subsurface;

• Proactive reservoir management in real time;

• Increased efficiency;

• Increased recovery factor;

• Efficiency in the drilling wells;

• Lower cost;

• Real-time reservoir optimization, wells and facilities;

• Improved water management.

The following technologies are associated with Intelligent Fields:

• Real Time Reservoir Management ;

• Real Time Drilling Control;

• Remote Monitoring and Control of Facilities;

• Surveillance Systems of the Production in Real Time;

• Intelligent Wells;

• Communication Technologies Involving Remote Data Transmission in Real Time and Data

Storage;

• Integrated Asset Model;

• Operations Integration Room for decision making, control, optimization and intervention;

• Networks of sensors permanently installed, continuous seismic, etc. ..;

• Administration system of the production;

• Administration system of the knowledge.

• And other;

In the future, Intelligent Fields will be impacted with technologies of Completations with Extreme

Reservoir Contact, Bionic Wells, and Nano Technologies such as:

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• Nanomaterials to improve the flow assurance creating more robust equipments;

• Nanofluids (smart fluids) with particles that enable a given fluid gets desired interwells properties;

• Nanosensors to measure temperature in the formations;

• Nanosensors to provide data on reservoir characterization and reservoir fluid flows.

• And others.

Figure 3: A schematic representation of intelligent fields. Modified from Field of the Future of the

BP.

4. Geophysical reservoir monitoring in intelligent fields

Traditionally, the purpose of the Reservoir Monitoring is to observe what is happening to the

reservoir during production. So that the monitoring serves among other things to:

• Identify in the regions interwells the bypassed or untapped oil;

• Evaluation of the efficiency of sweeping;

• Monitoring the movement of the heterogeneities;

• Updating of the simulation models and through them to get better reservoir management.

Nowadays these tasks are accomplished through:

(1) Integrated Reservoir Simulation Models;

(2) 3D/4D seismic;

(3) Information from wells;

(4) And others;

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A theoretical approach of Intelligent Fields can be seen in Figure 4.

Figure 4: A Theoretical Smart Field.

In the Figure 4 there are three different parts, well established:

(1) Monitoring;

(2) Modeling;

(3) Optimal Control.

Note that the Reservoir Monitoring in Intelligent Fields has different characteristics of the traditional

concept of reservoir monitoring. Intelligent fields are made up of networks of sensors permanently

installed in wells on the seabed and in the surface. These sensors measure in real time, variations

of the dynamic aspects of the reservoir due to production and injection of CO2 or others products.

And these measurements enable the continuous monitoring in order to infer different properties of

the reservoir in real time. There are different geophysical techniques being tested to measure

different physical parameters and infer reservoir properties. Some have well-proven efficiency and

others are being tested. Figure 5 is illustrative. Below are discussed some of these techniques.

CO2 Monitoring

Monitoring is one of the most important aspects of the Geological Storage of CO2. There are a

number of techniques that can be used for monitoring of CO2 storage projects. The appropriate

choice depends on: (1) features such as the position, depth, and temperature of the storage

location, and properties of the injected CO2, (2) surface characteristics over the storage location,

(3) the environment of the storage site, if it is offshore or onshore, and others. Some concerns the

monitoring of CO2 storage are as follows:

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Ensure that the injected CO2 is going to layer sub-surface intended;

Check the amount of CO2 injected;

Ensure that the injected CO2 is contained in the desired geological formation;

Monitor the conditions of injection wells, formation pressure and wellhead;

Predict leaks of CO2;

Detect leaks of CO2;

Define mitigation of CO2 leaks;

Figure 5: Geophysical Techniques for Reservoir Monitoring in Intelligent Fields.

Below are discussed some techniques showed in the Figure 5. These techniques are being tested

for the CO2 monitoring and Oil production.

Real Time microseismic Monitoring: The multicomponent seismic receiving arrays permanently

installed on the seabed can be used to record seismic data continuously. This information enables

the imaging of fractures networks, hydraulic monitoring, CO2 injection and others. The physical

properties measured are passive seismic waves. The reservoir properties inferred are fluid

saturation, pressure change. Figure 6 shows an illustration of the imaging of passive seismic

hypocenters with time lapse seismic.

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Figure 6: Microseimic Event Localization with Time-Lapse Amplitude Difference in the CO2

Monitoring. EGS Solutions.

Electroseismic: Electroseismic methods also known as Seismoelectrical methods are based in the

generation of electromagnetic fields when the seismic waves pass through a dielectric layer of

formations saturated with fluid. With base in these information the seismoelectrical methods are

able to detect the presence of fluid and monitor its movement. The Figure 7 shows the

representation of this methodology. The physical properties measured are seismic from electro-

kinetic coupling changes and Resistivity changes. The reservoir properties inferred are fluid

saturation and pressure changes. Research are developed in the application of Electroseismic

monitoring of the CO2 storage Zyserman (2010).

Figure 7: The eletroseismic confirms the presence of fluid and can monitor their movement.

Dasgupta (2008)

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4D Micro-gravity: The gravimetric prospecting makes it possible to analyze the interior of the earth

with basis in gravity anomalies, which can reflect the density of the subsurface materials. Gravity

surveys can detect the movements of fluid in the subsurface. Note in Figure 8 a real case study, in

a project of monitoring of the CO2 injection in the subsurface at Prudhoe Bay Field, Alaska.

Nowadays the micro-gravity surveys have high precision, enabling monitoring of fluids in reservoirs

with low cost. There are projects that have chosen this type of monitoring in relation to the 4D

seismic monitoring. In the 4D Micro Gravity the physical properties measured are density

differences, gravitational field changes, and the Reservoir property inferred is saturation 4D

changes.

Figure 8: Gravimetric monitoring of water injection in the gas cap. Project of CO2 Injection in the

Prudhoe Bay Field, Alaska.

Sattelite Techniques and Tiltmeter: These techniques are applied in the detection of alterations in

the surface, which can be attributed to very small variations in the land. InSAR (Interferometric

Synthetic Aperture Radar) use two or more images of radar to yields deformations maps of the

surface. The Figure 9 shows the application of this technique in the CO2 Storage Monitoring. The

physical properties measured surface deformation and poroelastic relaxation and the reservoir

property inferred is the volumetric reservoir change.

Seismic Techniques: Of these techniques the more applied in the Reservoir Monitoring in

Intelligent Fields are Time Lapse Seismic, Vertical Seismic Profile, Moving Source Profiling,

Crosshole Tomography Imaging. In the petroleum industry, the time lapse seismic captures the

dynamic of the reservoir due the production and injection. Its consists in the analysis of seismic

surveys (2D and 3D) obtained in different dates. The conception is that changes ocorred in the

reservoir state characterized by saturation, temperature and pressure in the poro fluid due to

production and injection, can be observed by changes in the seismic data obtained in different

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times. The Figure 10a and 10b show the application of the Time Lapse Seismic in the Sleipner

Field.The others techniques (Vertical Seismic Profile, Moving Source Profiling, Crosshole

Tomography Imaging) are borehole seismic measurements has higher spatial resolution, but act

only in the injection point, that is around wells.

Figure 9: Image obtained with the use of InSAR after 3 years of CO2 injection. The regions of

strong blue color show the concentration of CO2 around of the injetors K501, K502, and K503.

Project In Salah.

Electromagnetic Monitoring: Nowadays it is possible to obtain information on the saturation of

fluids in the vicinity of wells using production data, well logs, and cores. However in regions

interwells there are few techniques available which can efficiently make this task. Electromagnetic

techniques can be efficiently used to measure the distribution of fluids in the pore space. When

there is a high electrical resistivity between hydrocarbons and water these techniques are able to

map and monitor fluids throughout the life cycle of the reservoirs. The Figure 11 show a Resistivity

Maps obtained from Crosswell EM tomography.

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Figure 10a: The figure represents 2D seismic sections obtained before of the injection of CO2,

1994, and during the injection in 1999, 2001 e 2002. Sleipner Field.

Figure 10b: Amplitudes related to seismic sections 1999, 2001 and 2002 in Figure 3a. Sleipner

Field.

Figure 11: Resistivity Maps between the wells A, B, C and Porosity Logs. Marsala (2008).

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The table 1 shows the principal geophysical techniques the physical properties that these

techniques measure and the reservoir properties inferred. Figure 12 shows the relative importance

of some techniques, its vertical resolution and area coverage.

Table 1: Main Geophysical Techniques for Reservoir Monitoring in Smart Fields.

Figure 12: Different Techniques for CO2 Monitoring its vertical resolution and areal coverage.

Schlumberger (2012).

5. Multi-component seismic monitoring by using optical fiber

The difference between the 4D seismic mentioned above and the multi-component seismic

monitoring by using optical fiber for the Permanent Reservoir Monitoring (PRM) is that the latter

is obtained in real time through permanent installations. And this allows that certain parameters

(such as unswept regions, pressure and saturation of the reservoirs, and others) can be observed

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instantly. Moreover, the production optimization can be consistently better performed and the

placement of wells executed more efficiently. The CO2 Saturation can be observed with accuracy.

The reservoir monitoring using fiber optics installed permanently on the seabed is a very important

tool in the development of Intelligent Fields. Compared to conventional 4D Seismic, as seen above,

the advantages are numerous. In the conventional seismic 4D there are problems concerning the

repeatability related to acquisition and processing, since generally the surveys involved (base and

monitor) have different acquisition geometries and different types of processing. These differences

make difficult the comparison of surveys and its analysis. On the other hand by using permanently

installed fiber optics this problem does not exist since there is a fixed location of the cables on the

ocean floor. It is expected that fiber optics have higher resolution and higher fidelity for a long period

with low maintenance which makes it highly attractive cost. The methodology of using fiber optic

seismic acquisition has a total freedom in terms of Azimuth and Offset.

The conventional 4D seismic works with the P-wave only. So that the rock anisotropy, the

movement of the fluids, changes in lithology cannot be captured. On the other hand, fiber-optic

multicomponent seismic systems record P-wave and converted S-wave which is vital to:

• Identification of lithology;

• Waveform Inversion of Multicomponent Data;

• Discrimination of fluids;

• Characterization of Stress Fields;

• Geomechanical reservoir characterization.

In Entralgo, R. et al. (2001) showed that the imaging based on the P-wave only, it is not able to

capture details subsalt seismic layers (The Figure 13 illustrates).

Optical telemetry systems can be used in the Permanent Seismic Reservoir Monitoring. These

systems eliminate the use of electronic equipment at sea like conventional seismic acquisition

systems. This decreases the risk of failure and therefore is safer and less costly. The optical

sensors for seismic acquisition are based on optical interferometry which has additional

advantages. These components impact significantly on the speed of seismic acquisition.

In the conventional electrical seafloor seismic acquisition systems, the sensors and cables of

interconections are subject the leaks and corrosion due to its contact with the water. So that the life

of these seismic installations become compromised. Fiber optic seafloor seismic acquisition

systems have not electronic components that can fail in contact with the water. The life expectancy

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of these systems is much higher, due the absence of corrosion of the equipment. Without any doubt

these systems are more viable for Permanent Reservoir Monitoring than the electrical acquisition

systems. The Figure 14 show the correlation between optical and electrical receiver gathers.

Figure 13: Illustration of the difference between the Streamer seismic imaging and Seafloor seismic

imaging in relation to Subsalt. Entralgo et al. (2001)

Figure 14: Receiver gathers from optical acquisition and electrical acquisition. Nash (2008).

For CO2 monitoring Multi-component seismic monitoring by using optical fiber is applied in the

same way that the 4D Seismic. The advantages with the application of these techniques are

mentioned above.

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6. Permanent downhole fiber optic pressure and temperature

In the CO2 monitoring these measurements are used to verify the integrity of cap rock and possible

phase changes. The variations in the CO2 phase in injection can cause changes unexpected and

uncontrolled pressure and temperature and disable the operation of closing CO2 injection wells.

Analysis of pressure can allow monitoring in the saturation of CO2. There are several potential

applications have not yet been tested for CO2 monitoring using permanent measurements of

pressure and temperature.

7. Conclusion

In this article we present an approach of Intelligent Fields. Present also Some aspects

technological, which will have a significant impact on the oil fields of the future. Moreover we

discuss the geophysical techniques that are being tested in the Smart field such as: 4D seismic, 4D

Micro gravimetry, Microseismic Monitoring, and others. We dedicate a section to Multi-component

seismic monitoring by using optical fiber for Permanent Reservoir Monitoring.

7. References

AL-DHUBAIB, T. Intelligent Fields: Industry’s Frontier & Opportunities. SPE 141874, 2011.

DASGUPTA, S. Emerging Geophysical Tools for Reservoir Monitoring Intelligent Fields. 2008

Honorary Lecture, Middle East and Africa,2008.

EDISON, L. The Value of Smarter Oil and Gas Fields. IBM Center for Applied Insights. Executive

Report.

EDWARDS, S. Oil and Gas 2030 – IBM Global Business Services. Executive Report, 2010.

ENTRALGO, R. The Challenges of Permanent 4C Seafloor Systems, The Leading Edge v. 20, no.

6, 2001.

FOSS, B. Performance Analysis for Closed-Loop Reservoir Management. SPE 138891-PA, 2008.

MARSALA, A.F. Ruwaili, S., Mark Ma, S., Ali, Z., Buali, M., Donadille, J., Crary, S., and Wilt, A.

Crosswell Electromagnetic Tomography: From Resistivity Mapping to Interwell Fluid Distribution.

IPTC 12229, (2008).

NASH, P. et al. Optimum Optical Architectures for Seismic Reservoir. OTC 19678, 2008.

ZYSERMAN, F., Santos, J., Gauzellino, P. et al. Electroseismic Monitoring of CO2 Sequestration:

Finite Difference Approach, Technical Report, (2010).