SPE-193778-MS
In Situ Heavy Oil Upgrading by Electric Enhanced Oil Recovery, Complex
Carbonate Heavy Oil Field Case
Kresimir Keglevic, White Falcon Petroleum Technologies AG
Copyright 2018, Society of Petroleum Engineers
This paper was prepared for presentation at the SPE International Heavy Oil Conference and Exhibition held in Kuwait City, Kuwait, 10-12 December 2018.
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
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Abstract
This paper describes novel electrochemistry based in situ heavy crude oil upgrading technology and also
field case and results of In Situ Oil Upgrading from Visoke Heavy Oil Field, Albania, produced oil changing
chemical composition results, as well as gains in crude oil production and reducing water cut.
EOR technologies such as various thermal methods, CO2 flooding and chemical floods have gained
increased interest due to the decreasing number of new-field discoveries, increasing number of maturing
fields and higher oil price.
Among the emerging EOR technologies, electro chemical Electric Enhanced Oil Recovery is the new
generation of tertiary oil recovery enhanced by electro kinetics (electro osmosis) and electro chemistry.
By tailored application of direct current on hydrocarbon reservoir between two wells, which serve as
anode (+) and cathode (-), usually several fold oil production increase is achieved at cathode well, while
production at anode well, if production well serves as anode, stays as before or slightly increased.
Method, if anode and cathode wells are cased and perforated, does not require any work over for
field application, just connecting control panel with power source (3 phase 380 V, 18 A, 50 or 60 Hz)
and electrically connecting control panel with well heads (casing or tubing) which previously should be
electrically insulated by insertion of resistive tube in production line.
Key points
•
•
•
•
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•
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Pre calculated pulsed DC current applied to oil formation
DC power is applied to oil bearing strata through existing wells
DC current and voltage predefined and regulated by special computer software
Desired effects gained by voltage and amperage alteration
Increases oil production, decreases W.C. due to electro kinetics and electro osmosis effect
Improves oil API, decreases viscosity, liquefies even very heavy oils due to REDOX reaction
Minimal well intervention required
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SPE-193778-MS
•
Low energy consumption, simplicity of application, environmentally friendly
Introduction and Background
Among discovered hydrocarbon resources, probably most neglected has been heavy oil and bitumen in
carbonate reservoirs. Heavy oil contained in carbonate reservoirs worldwide is estimated to be 1.6x 10(12)
bbl in place. So far, this major resource has attracted little attention from the petroleum industry and little
has been produced. This probably stems from the conceptually difficult task of recovering viscous oil from
naturally fractured carbonate formations. Clearly, a means of reducing oil viscosity, is needed to allow flow
to producing wells.
Steam injection is currently the most widelly applied Enhanced Oil Recovery technique applied to unlock
heavy oil deposits. However, in carbonate reservoirs, steam might be expected to travel preferentially
through the fracture system and to recover little oil preferentially through the fracture system and to recover
little oil from the matrix; The chemical reactivity of the formation to the steam injectant also might be
expected to cause problems in the forms of formation damage and scale production. Furthermore cost of
steam injecting facilities im many cases is prohibitive factor for it's application.
Cost effective alternative for conventioal thermal EOR methods is hereto described variant of Electric
Enhanced Oil Recovery technology due it's simplicity and wide area of potential application.
EEOR Technology described in this paper has two main features related to Electro Chemical Processes
(ECP), namely electro kinetic and electro chemical oxidation applications.
Electro kinetic is applied in the form of electro osmosis, which drives water and already liquid oil, through
the formation towards the cathode from the anode. This speed up the drive through the formation and
increase the amount of fluid (bfpd) coming to the cathode well. Electro osmosis is state of the art and well
described in the literature.
Technology in Brief
Crude Oil Breaker Electric Enhanced Oil recovery technology is an electrochemical technology sui generis
which utilizes Electro Chemical Oxidation (ECO) to achieve irreversible improvement of heavy oil quality
ad in situ decrease of oil viscosity.
The performance of this technology is based on the colloid structure of the soil particles, giving way
for the colloid conductance allowing high amperages at low voltages. The colloid conductance forces
the electrons on the micro-scale to cross electrochemical interfaces at which simultaneously reactions of
reduction, and oxidation (redox) take place decomposing heavy crude oil to lighter constituents. The agents
for the redox reactions are generated in-situ by water electrolysis. Pre conditional is, however, that the Eh
(redox potential) is in the positive range of >200 mV. The energy supply is supported by the amplifier
phenomenon of soils which need to be controlled in order to avoid exceedance of the technical performance
data of the electrical ac/dc converters employed.
Electro-Chemical Oxidation
Electro chemical oxidation (ECO) is creating Redox reactions in the formation which leads to a liquefaction
of heavy crude, or said in another way, leads to breaking up long chained carbon chains at preferred
places like C12, C6 and C3 by so-called cold cracking inside the formation. The change in the chemical
composition is not reversible and the oil will remain liquid with a higher API, lower viscosity, lower PP
and sometimes lower amount of Sulphur content.
Electro Chemical Oxidation (ECO) belongs to a group of four electrochemical processes applied in and
to soils which have been detected consecutively since 1809, starting with ELECTROOSMOSIS, defined
as transportation of water through a semipermeable membrane whereby a dense soil is considered as a
SPE-193778-MS
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semipermeable membrane. In about 1860 ELECTROKINETICS (such as electrolysis and electrophoresis)
have been detected effecting a transportation of ions and complex ions in an electrical dc-field through
the capillary system of the soil. In about 1930 ELECTRODIALYSIS has been discovered, a special form
of electro kinetics. In 1990 GEO OXIDATION has been detected by accident when unexpected results
occurred in the field application of electro kinetics; geo oxidation relates to electrochemical reactions
(Redox-reactions) caused in soils similar to the electrochemical synthesis in industry. The following features
are specific for ECO: ECO applies a direct current to the soil which we define as a colloidal system. The
current introduced by ECO into the soil is defined hereinafter as primary current whereas the redox-reactions
are caused – properly speaking - by the secondary current generated by the soil itself. In this paper there is
no need for an additional contribution to traditional electrochemistry; we are, however, required to address
specific issues related to geophysics in order to explain the process, such as the effects of the polarization
of the soil.
Electro Chemical Oxidation (ECO), emerged from the research on "Induced Polarization"(IP). (V.
Vacquier et all, 1957.) IP establishes artificial electric fields in rock and concludes from the behavior of the
decay curve of the electrical current, when switched off, on ore or water deposits. The decay curve of the
electrical current can be subdivided into analytical "windows". The principle of IP, namely the switching
process, and the transient decay of power in rock due to membrane (electrolytic) polarization and electrode
(electronic) polarization, the latter in the presence of metallic minerals in rock.
Two methods are known for IP detection: when the decay voltage is measured as a function of time, this
method is described as time-domain IP. The measurement of two or more frequencies constitute another
method of detection, known as frequency-domain IP. On the basis of IP, ECO emerged as a technology sui
generis combining frequency and time domain IP with a long term, uninterrupted flow of a direct electrical
current. ECO is distinct from hitherto electrochemical separation technologies such as electro osmosis,
electrophoresis, and electro dialysis. As a rule, electrochemical soil remediation is an in-situ process that
applies an electrical current to probes driven into the ground to rapidly address a wide range of organic
constituents.
The element of electrochemical remediation technologies is the application of a DC intended to improve
the energy balance of the remedial action in soils in lieu of either a DC or a frequency modulated current.
Under these conditions, basic elements of IP were required to be reexamined, namely the shape and the
functions of the so-called double layer structure of the mineral particles and possibly accompanying clay
layers, the place and the function of the interfaces within the double layer structure, issues related to the
relationship water / resistivity and sudden changes of the resistivity as reported by T.J. Katsube, the types
of electrical conductors, and the existence of a resistor/capacitor (R-C) scheme.
As mentioned above, IP already identified the above R-C-circuit. When complementing the RC-circuit
by the phenomenon of induction, i.e. the movement (spin) of free electrons in an electric field, we obtain
the following situation:
In electronic science The RCL-structure of soil is known as amplifier. The rate of amplification is
dependent on the type of soil (oil bearing rock), the water content, and the duration of the action. Field
research identified amplification factors of 1,000 to about 8,000 and more causing in some instances a
burn-out of the electrical supply system. The phenomenon of amplification on the other hand provides the
secondary current, which is responsible for ECO to work even at low voltages and amperages delivered by
the primary current. The central problem, therefore, is not the low primary energy delivered to the electrodes,
but the control of the amplification of electric power to the secondary power delivered to the soil (oil bearing
rock formation).
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SPE-193778-MS
Redox Reactions
Oxidation of organic substances stands for donation of electrons whereas reduction stands for acceptance
of electrons.
Both reactions occur simultaneously at interfaces described above. These processes, however, in most
cases when affecting organic substances, require the presence of oxidizing and reducing agents. These agents
are generated by ECO in-situ by water electrolysis. By primary processes and secondary reactions, the agents
are generated such as elemental Hnasc, HO radicals and ions, HO2ions and radicals and hydroperoxides, as
well as elemental oxygen (Onasc) and ozone.
Oxidation comprises of exothermic processes related to the electrochemical conversion of substances into
alcohols, aldehydes, organic acids which under the conditions of ongoing oxidation decompose to carbon
dioxide and water. Reduction means stepwise substitution of p.x. halogens by hydrogen, ring opening of
aromatic constituents or cleavage of aliphatic compounds at preferred breaking points (C10/12; C5/6, C2/3).
The central task for any ECO/EEOR application relates to the establishment of an oxidized environment
at pH in the range of neutral and Eh (electrode potentials) in the range of >200 mV. First results of field
tests related to the treatment of fresh water sediments indicate that ECO can substantially raise the Eh9.
Visoka Oil Field Geology
The Visoka oilfield is situated in one of the most geologically studied regions in Albania, because it is an
oil-bearing area where many wells have been drilled, and many studies have been conducted. The following
three types of formations: Carbonatic, Flysch and Mollastic were found in the Patos-Verbas structure and
in the Visoka region. Carbonate formations are represented throughout their thickness by the Lower and
Middle Eocene up to the dolomites of the Upper Triassic, which have been penetrated by the deep well
Verbas-3. The exploitation section in the Visoka oilfield is the limestone of Cretaceous – Eocene age. These
formations are represented by limestone of the mudstone type, mainly in the upper limestone part, which
gradually switch to grainstone and debris flow horizons as moving toward the lower part of Eocene. In the
oldest deposits, those of Paleocene and Cretaceous, the quantity of grainstones and debris flow increases
vertically, positively influencing the enhancement of rock properties. The oil-bearing thickness of the Visoka
reservoir is concentrated in these formations which from the rock property aspect, and for practical reasons,
are divided into lithological packages. In the central part of the structure these deposits are eroded. The top
carbonate is covered by the marine transition zone, which is 30-35 m thick. The limestone of Lower and
Middle Eocene are covered by a considerable thickness of flysch deposits dating Oligocene (Pg3). These
formations are represented by a characteristic flysch intercalation: argillites, alevrolites and sandstones.
They serve as an impermeable cover for storing the oil and gas reserves in the carbonate reservoir.
These deposits were penetrated by all the wells drilled in the south of the eroded surface of the limestone.
Their thickness is about 600-700m. Above these deposits, there are found flyschoid deposits dating Langania
and Serravalian period. Mollase formation is the third type, and comprises Upper Miocene deposits, to
younger deposits. These deposits are placed transgressively, over the older deposits, in age discordance. In
the uppermost part, that of Zharrez and Sheqishte, they are found over the eroded limestone, from where they
were impregnated with oil. The oil-bearing suites of Goran, Drize, Marinza and Bubullima, which constitute
the Patos-Marinze oilfield, are part of this formation. This formation is represented by Mollastic deposits
of the post-orogene cycle and oil-saturated sandstones strata which are divided in argillite intervals. In the
upper part, the sandstones of Kucova suite are water-saturated. Their thickness is 400-500 m, increasing
toward the north-west. Younger deposits such as those of Pliocene are placed over the older one. They are
represented by argillaceous facies (Piacenzian) and Astian conglomerates.
SPE-193778-MS
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Figure 1—Visoke oilfield 3 D structural profile displaying four packages Source: Visoka Oilfield Study, dr. Ajet Manzini, 2010.
Visoka oilfield reservoir characteristics
The severe heterogeneity of the rock properties and permeability in particular, was proved by a hundred
drilled and exploited wells in the Visoka oilfield.
Createous-Paleogene: The lithological composition of these deposits is made clear because of the data
collected in many drilled wells and also from the many studies carried in the surface sections of other
structures in the south of Visoka (Kremenara, Mezini A, Swennen R, 2006). The main lithological features
of these deposits are as below:
Upper Cretaceous: It is represented by the packstone and the interclastic and bioclastic wackestone. There
are also found grainstones, sliding horizons and chert lenses. In the formations of the Upper Cretaceous you
may also find intercalations of the cemented rudists of the syntaxial cement type. A quantity of the matrix
porosity was developed from the selective solution of Micritic. Porosity here, particularly in the lower part
of the Upper Cretaceous is much more developed than in other deposits.
Paleocene: It is mainly represented by the bioclastic packestone and wackestone, intercalated with debris
flow and sliding horizons. Because of the high presence of grainstone and carbonate debris in the section,
petro physical properties are better than those of Middle and Lower Eocene.
Eocene: Eocene is characterized by the predomination of the slim bedding with few grainstone and debris
flow intercalations of the pelagic mudstone (Mezini A., Swennen R., 2006). The matrix porosity in these
deposits is developed only when the matrix is separated and when the fractures and stylolites are created.
Since it is slim bedded and more compact than other lithologies, fractures are more developed in the deposits
of Eocene.
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SPE-193778-MS
The oil and gas-bearing section in the Visoka oilfield, for a practical purpose, it is separated into four
lithological packages, which stand out for their lithology and porosity. In the Visoka oilfield, we find the
following packages:
First package: includes the upper part of the carbonate reservoir of Lower and Middle Eocene. In the
Visoka field it reaches 80 m thickness (Pic.5). In the logging these deposits have a high resistance, and are
shown as of slim carbonate bedding without any development of the spontaneous polarization. At the end
of this package the curve of spontaneous polarization changes immediately and that shows the presence of
developed fractures. Generally, this package isn't characterized by developed matrix porosity. Many wells
have had mud loss, because of the presence of fractures in this package.
Second Package: This package contains more limestone debris and grainstone horizons. You may also
find sliding horizons in this package. The change in lithology from the first package is clearly noticed from
the curve of spontaneous polarization which is much more developed in this fracture (Pi.5). This package
was penetrated by the greatest part of wells drilled in the Visoka oilfield. It is 60-70 m thick. (Ndoni S.,
1999).
Third package: This package is mainly represented by deposits of the Upper Cretaceous in which the
debris limestone intercalated with packstone and debris flow predominates. A characteristic of these deposits
is the presence of thick clastic carbonates. In the logging you can notice a very high resistance and the
development of the spontaneous polarization is related to the fractures, and to the porosity developed in
this package. The third package was penetrated only by those wells which are more than 120 m deep in
limestone. It is 120 m thick.
Fourth package: This package was penetrated by a limited number of wells. It is represented by an
intercalation of micritic limestone with grainstone. The floor of this package is at the beginning of the
phosphorous horizon which marks the end of the Upper Cretaceous. The average thickness of this package
is 140 m.
Figure 2—Visoke oilfield''s representative wells log diagrams and their division
in limestone packages Source: Visoka Oilfield Study, dr. Ajet Manzini, 2010.
SPE-193778-MS
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Reservoir rock properties
Opened porosity, or the effective porosity measured in the lithological packages fluctuates in large
differences. The effective porosity of the Cretaceous-Paleogene reservoir increases when moving from the
top carbonate toward the older carbonate.
The porosity average changes from 1.7% in the first package, 2.224 % in the second package and 8.1% in
the third package. The average value of porosity may have a slight change in difference from one part of the
formation to the other, depending on the predomination of the lithologic composition. Porosity increase with
depth is present everywhere. Highest porosity is present in the bioclastic debris flow and the grainstone of
the lower part of the Upper Cretaceous. If we consider other indirect data for the Visoka oilfield regarding the
mud loss, instrument drop, drilling advance, WOC advance, permeability etc., the above values of porosity
are acceptable.
The lowest average value of porosity in the first package, which is 1.7%, is related to the predomination
of the mudstone, or of the pellitic material in the section. Oilfield data regarding mud loss since in the first
meters of carbonate drilling and the high rates in which the oil in this package is exploited indicate the
predomination of the fracture porosity. Such a thing is made more evident when we compare the value of
secondary porosity 2 %, taken from the interpretation of geophysical measurements.
Porosity values in the second package are higher than the first package and have the value 2.224 %.
The debris organogene and the debris flow predominate in this package. A greater development of the
Spontaneous Polarization curve is noticed in the logging.
Concerning the rock properties the third package is the best package. This is related to the presence of the
thick horizon of debris organogene, debris flow and the grainstone of a developed porosity. Matrix porosity
predominates over the fractures porosity in this package.
The most (90%) wells of the Visoke oil field have permeability over 10 Darcy.
Figure 3—Bioclastic packestone with rudist and pellagic foraminifere of
the first package Source: Visoka Oilfield Study, dr. Ajet Manzini, 2010.
Oil and Gas Properties
The oil of Visoka oilfield is of asphalting – resin type, with specific weight, high viscosity, and a high
content of the heavy fractions. The specific weight in the surface conditions is between the values 0.990
– 1.0288 gr/cm3
The specific oil weight changes increasing, when it is passed to the north direction, and also from up
down, approaching to the oil-water contact.
The oil viscosity in the in situ conditions (40 deg C) is calculated to vary from 15.000-41.000 cP. The
sulfur content in the oil is high, 5.5-6%.
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SPE-193778-MS
Field Installation
EEOR's control panel and signal generator has been installed between wells G-6 as cathode well and well
G-86 as anode well in December 2017. Both wells are completed as open hole wells, therefore as part of
preparation, workover is performed on both wells, to extend tubing string down to the bottom.
Tubing extension was needed because wells are completed as open hole, it means we had to utilize tubing
as conductor for direct current supplying electricity into oil formation.
Figure 4—Well sketch – preparation for EEOR application G-6 well, Visoke oilfield, Albania
Well G-6 TVD is 1226 m, method of artificial lift is sucker rod pump, completion is open hole, after
cement plug to isolate lower part of wattered out formation, open hole zone lenght is just seven meters.
Electric power source for EEOR control panel/signal generator was placed in dedicated container next to
well G-6 (cathode well), and electric cable was then stretched on existing pillars to well G 86 (anode well).
Control panel/signal generator was supplied by 3 phase 380 V 50 Hz electric power from existing nearby
grid (which supplies sucker rod with electric power), than converted DC signals were sent through stretched
single core cable which was attached to both wells wellheads-wellhead of G-6 (cathode well) and wellhead
of G-86 (anode well).
SPE-193778-MS
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Figure 5—electric connections sketch
Electric cables carrying DC signals were attached to both well's wellheads by clamps, and than insulated
by insulation tape. Delivered voltage does not exceed 200 millivolts, therefore such way of cable attaching
is possible.
Figure 6—electric cable connected to the wellhead Source: White Falcon Petroleum Technologies AG.
For ensuring electric insulation of the wellhead, casing and tubing from surface piping system, short tube
of electric insulating material should be inserted, preferebally as close as possible to the wellhead.
For this purpose, we used coil resistant rubber pipe, pressure resistant up to 25 Mpa, attached on each
side by flange with steel tubes, as shown on picture.
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SPE-193778-MS
Figure 7—rubber tube insertion Source: White Falcon Petroleum Technologies AG
Field application results
EEOR has been installed between wells G-6 as cathode well and well G-86 as anode well in December
2017. Those two wells were chosen as candidates, because of proven hydraulic communication between
them, which is necessary for successful performance of EEOR/ECO technology to liquefy heavy oil and
increase production on cathode well.
Production of oil and formation water from the well G-6 was measured each day during two weeks prior
to EEOR/ECO Crude Oil Breaker control panel and signal generator installation and connection to cathode
(G-6) and anode (G-86) well.
Table 1—Well G-6 production data for November 2017.
Well no
Lifting
method
Crude
Oil (Ton)
Working Days
Average daily
production
(Ton/day)
Water (Ton)
Water(%)
G-6
SRP
13,5
29
0,46
270
95,24
After putting EEOR into operation, liquid level in the annulus started to increase, due to electro osmotic
effect, which is secondary in this application, although present to some extent.
Fluid level was measured by sonolog, and from 06.12. 2017. to 17.01.2018. increased from 40 meters
from the surface to 15 meters from the surface.
After about six weeks of soaking period, first signs of liquefaction on well G-6 occurred, which were
visible by naked eye.
EEOR's main mechanism of oil production increase, when applied on extra heavy and viscous oil
(bitumen) deposit as Visoke is in situ viscosity decrease, therefore main measured parameters were
oil viscosity taken from G-6 (EEOR/ECO treated well) and G-625 (reference well). Second important
parameter indicating EEOR/ECO technology effect is changing of produced oil chemical composition,
therefore SARA analysis has been performed for sample taken from G-6 and G-625.
SPE-193778-MS
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Third measured parameter was changes in API value of oil produced from G-6 vs oil from reference
well G-625. Wells G-6 and well G-625 produces from same layer of Visoke oil field, and are about 250
meters distant.
Tests were performed by different laboratories namely:
– INA chemical laboratory, Zagreb, Croatia (SARA and viscosity analysis at 50 deg C)
– Bankers oil company field laboratory: API (spec gravity)
INA's chemical laboratory performed tests of SARA analysis and viscosity analysis of two samples, one
being taken from well G-6 (EEOR/ECO) and other from well G-625 (reference sample).
Saturate, Aromatic, Resin and Asphaltene (SARA) is an analysis method that divides crude oil
components according to their polarizability and polarity. The saturate fraction consists of nonpolar material
including linear, branched, and cyclic saturated hydrocarbons (paraffins). Aromatics, which contain one or
more aromatic rings, are slightly more polarizable. The remaining two fractions, resins and asphaltenes,
have polar substituents. The distinction between the two is that asphaltenes are insoluble in an excess of
heptane (or pentane) whereas resins are miscible with heptane (or pentane).
1st SARA analyses:
•
•
•
Samples taken: 2nd April 2018
Samples delivered to laboratory: 3rd April 2018.
SARA analysis performed during April 2018., by chemical laboratory of INA Plc. (www.ina.hr)
Table 2—results of the first SARA analysis, INA lab, April 2018.
samples
Saturated
hydrocarbons
(mass %)
Aromatic
hydrocarbons
(mass %)
NSO resins (mass%)
Asphaltenes
(mass %)
Sample A (reference
well G-625)
14,61
45,47
18,93
20,99
Sample B (well G-6),
EEOR test in progress
18,05
48,28
14,81
18,86
2nd SARA analyses:
•
•
•
Samples taken: 30th June 2018
Samples delivered to laboratory: 5th July 2018.
SARA analysis performed during July 2018., by chemical laboratory of INA Industrija nafte d.d.
(www.ina.hr)
Table 3—results of the second SARA analysis, INA lab, June 2018.
samples
Saturated
hydrocarbons (mass %)
Aromatic
hydrocarbons (mass %)
NSO resins (mass%)
Asphaltenes (mass %)
Sample A (reference well G-625)
14,22
47,39
15,33
23,08
Sample B (well G-6),
EEOR test in progress
22,44
45,61
12,92
19,04
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SPE-193778-MS
Viscosity measurments
Table 4—kinematic and dinamic viscosity of sample A (reference well G-625), INA chemical lab, April 2018.
Well G-625 (reference well)
Viscosity at 50 deg Celsius (ASTM D7042)
result
Dynamic, mPa s
28.076,0
Kinematic, mm2/s
27.983,0
Table 5—kinematic and dinamic viscosity of sample B (EEOR cathode well G-6), INA chemical lab, April 2018.
Well G-6 (EEOR cathode well)
Viscosity at 50 deg Celsius (ASTM D7042)
result
Dynamic, mPa s
2.615,0
Kinematic, mm2/s
2.646,6
Table 6—kinematic and dinamic viscosity of sample A (reference well G-625), INA chemical lab, July 2018.
Well G-625 (reference well)
Viscosity at 50 deg Celsius (ASTM D7042)
result
Dynamic, mPa s
26.496,0
Kinematic, mm2/s
26.345,0
Table 7—kinematic and dinamic viscosity of sample B (EEOR cathode well G-6), INA chemical lab, July 2018.
Well G-6 (EEOR cathode well)
Viscosity at 50 deg Celsius (ASTM D7042)
result
Dynamic, mPa s
2.146,0
Kinematic, mm /s
2.164,6
2
API improvement
Measuring taken place at analityc laboratory of Bankers petroleum company, Patos, Albania Samples are
first freed of water bz centrifuging, than specific gravity (API) was measured.
Table 8—changes in API value, April 2018.
Specific gravity (at 15° C)
API
Sample B Well G-6 (EEOR)
Sample A Well G-625 (reference)
1.004 g/cm3
1.022 g/cm3
9,4
6,8
Production improvement
Production of oil and water was measured once per month, by diverting production from G-6 well to
dedicated reservoir. Other days, production from G-6 were conmingled with production from other wells.
Table 9—changes in oil production and water cut
Date of measurment
Oil production (bpd)
Water cut (%)
03.12. 2017.
2,52
94
15.01. 2018.
7,56
80
14.02. 2018.
12,20
72
20.03. 2018.
14,18
71
SPE-193778-MS
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Date of measurment
Oil production (bpd)
Water cut (%)
16.04. 2018.
16,35
61
20.05. 2018.
17,20
52
18.06. 2018.
18,91
47
Conclusion
Electrochemical oxidation EEOR in situ crude oil breaking technology capability to liquefy and improve
quality of extra heavy oil from Visoke deposit is clearly demonstrated.
Based on lab test results of the samples taken from well treated by ECO/EEOR in situ crude oil breaking
technology, real production measurment results of the well G-6, as well as electric power consumption, the
following conclusions may be drawn:
– Extra heavy crude oil has been liquefied, and liquefaction process started about 6 weeks after putting
ECO-EEOR technology into operation
– Field application required very simple installation, however cathode and anode wells (G-6 and G-86)
should be workovered before installation in order to extend tubing within open hole zone.
– Electro chemical reactions coused in situ upgrading of extra heavy oil, which is verified by two times
performed SARA analisys; results of both clearly indicated decrease of asphaltenes and resins, with
simultaneous increase in saturates and aromatics mass percentage.
– Electro chemical reactions coused dramatic decrease of oil viscosity
– After four months after technology has been put into operation, API value improved by 2,6 points,
from 6,8 to 9,4
– Power consumption was average 1,1 KWh
– Production increase due to reduced oil viscosity
– ECO-EEOR is viable enhanced recovery option for increasing production and recovery factor of
heavy and extra heavy oil from complex carbonate reservoirs, with high permeability, low porosity
and strong bottom water drive
Nomenclature
AC
Bfpd
Bopd
DC
ECO
ECP e
EEOR
EOR
INA
IP in
R-C
SARA
SRP
TVD
W.C.
– alternating curent
– barels of fluid per day
– barels of oil per day
– direct current
– electro chemical oxidation
– lectro chemical process
– electrically enhanced oil recovery
– enhanced oil recovery
– Industrija Nafte d.d.
– duced polarisation
– resistor - capacitor
– saturates, aromates, resins, asphaltenes
– sucker rod pump
– total well depth
– water cut
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SPE-193778-MS
References
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