AGAR CORPORATION

Process Measurement & Control

Multi-Phase Measurement Options Associated Problems

Basic Multi-Phase Flow Measurement Formulas

1.2 - MPFM Formulas

Nuclear energy absorption (X-Ray Affect)Nuclear energy absorption (X-Ray Affect)

The paper shows the effect of other minerals (such salts, rust etc.) on the output readings. To return tothe original calibration, complicated and hazardous cleaning with Hydrochloric Acid is recommendedby the vendor. To accommodate this cleaning process complicated valve/piping installation arerequirements.

This mineral effect is applicable to all nuclear based MPFM's not just the Schlumberger/Framo device,Roxar-MFI/Fluenta, Daniel.

The paper shows that nearly 50% watercuterror can occur due only 300 Microns(about the size of 3 human hairs) of scalebuild-up or 1% by volume.

The explanation is simple. When one getsan x-ray by the doctor, the bones(Calcium-Carbonates) show very clearly,while the flesh (Hydrocarbons) is hardlynoticeable. Yet, the densities of the two arevery similar.

OTC-13152

Fig. 5 OTC 13152

The majority of encountered contaminations, consist of NaCl, BaSO4,SrSO4, ZnS, and CaCO3. They are all characterized by the presence ofatoms heavier than H, C and O that compose oil, water and gas. The spectralgamma ray detector of the multiphase flow meter is affected by the presence of these heavy elements .

Shown here is the 300 series meter showing the positive displacement meter for total volumetric, momentum for GVF and Water Cut meter for %water ...

MPFM Basic Calculation LogicMPFM Basic Calculation Logic

Measure Q(vol.)

Measure DP(mom1)

CalculateQ(g), Q(l)

CalculateQ(w), Q(o)

MeasureWatercut (c)

DisplayQ(o), Q(g), Q(w)

Measure DP(mom2)

Agar MPFM 300 SeriesAgar MPFM 300 Series

The Agar MPFM-301 Installed at Petrozuata

MPFM 301 Capacities

20 %

40 %

50 %

60 %

70 %

30 %

GVF10 %

80%

90%

0

5000

10000

15000

20000

25000

0 20000 40000 60000 80000 100000 120000 140000

Gas ACFD

Liq

uid

BF

PD

MPFM 301-20

MPFM 301-30

MPFM 301-40

Well Data

GVF Effect on Profitability

• GVF = Fg = Qg/(Qg + Ql) ………….(1)• Fg * Qg + Fg * Qg = Gf

• Qg = Ql * [Gf / (1 - Fg )] …………….(2)

• Case 1: Fg = 0.90; Qg = 0.90/0.10 = 9 Qg

• Case 2: Fg = 0.95; Qg = 0.95/0.05 = 19 Qg

• Case 2: Fg = 0.99; Qg = 0.99/0.01 = 99 Qg

AGAR 300 Series MPFM shown installed for Shell de Venezuela’s Lake Maracaibo Icotea #1 Platform

Shell originally acquired two MPFM’s in January 1995 and then reordered two additional units in August 1996. For a total of 4 units on Icotea #1, #2, #3 and one as a spare.

Water Salinity TestWater Salinity Test

This graph shows the independence of Agar OW-201 on changing salinity of the process water. In cases where steam or ocean water is used to recover oil, the salinity of the process fluid changes drastically. Salinity has a tremendous effect on water cut since the NaCl ions are good conductors. The Agar OW-201 monitors and measures not only the water cut but also the salinity of the process water and compensates the water cut with this salinity reading….

401 MPFM Capacities

60 % 70 %80 %

90 %

95 %

GVF50 %

98 %

0

5000

10000

15000

20000

25000

Gas ACFD

Liq

uid

BLP

D

401 20-20

401 30-30

401 30-40

401 40-40

401 40-60

AGAR WET GAS METER

AGAR 400 Series MPFM

The Use of a Multiphase Flow Meter to Optimize Gas Lift Well Operations

By: Dr. Atef A/Allah A/Hady,Production Division Manager,

Gulf of Suez Petroleum Co

GUPCO October Field - Minimum Structure Platform

MPFM replaces 2 phase well tester sized for 12,500 BBL/D and 550,000 ACFD (actual)

Well 2 indicates a serious problem with the well operation. Notice the severe heading in liquid production and gas injection. The conclusion was that the well either had a bad gas lift design, a mechanical failure of the gas lift valves, or communication between the casing and tubing. This problem is easily shown by the Agar MPFM real-time data. This would have been virtually impossible to find using only a standard test report.

The indications were that there was a mechanical failure in the gas lift valve or poor spacing of the valves, which prohibited us from working down-hole to the lowest possible injection point. Additionally, upon checking the characteristics of the produced water confirmed that all water was from the producing formation.

Mobile Well Testing - Shell Oroni Field - NigeriaUnit Acquired in June 1999

Full Scale testing started on July 22, 1999 at the Shell Petroleum Development Corporation (SPDC)

Oroni Field in Nigeria

Conclusions

• Daily Reconciliation factors (total production versus sum of individual wells) showed very good improvement with the MPFM data

• Agar MPFM water cut measurements were accurate compared to laboratory data (Dean and Stark method)

• Oil rate, Water cut, and Gas Oil Ratio measurements showed good repeatability

• Wells with surging and slugging flow patterns can be identified

• The results show that the mobile Agar MPFM can be used to calibrate test meter

Note this is steam flood application and water salinity ranges from steam condensate (0% salinity) to Brine (100% saturated water)

Appendix ACustomers Testimonials

Agar MPFM Test in KSEPL – Shell E & P Report Chris Wolff – KSEPL Dave Brown – KSEPL “The test was conducted from 11/17/92 to 11/24/92. A 2" AGAR MPFM was tested using factory calibration settings. The MPFM was tested with watercuts of 0% 20%, 50% and 100%. The liquid superficial velocity varied from 0.34 to 3.4 m/s and the gas superficial velocity varied from 0 to 4.24 m/s... The Gas Void Fraction with the lowest liquid flow rate and the highest gas flow rate was above 95%. The liquid component flow measurement accuracy was better than 10% of reading for a wide range of flow rates and Gas Void Fractions, and better than 5% of reading for about half of the data points. Reading taken on the last day of the test showed very good repeatability when compared with readings taken earlier in the test. The data shows that some of the error falls into a pattern that could be compensated with calibration. Gas component flow measurement accuracy was better than 10% of reading for all flow regimes.”

Testimony # 2 - From Texaco's JIP report Executive Summary. Tests were conducted in November 1994 at the Humble multiphase loop.

EXECUTIVE SUMMARY

The Agar APFM 301 multiphase flow meter is intended for metering oil, water, and gas multiphase flowproduction streams with gas fractions from 0 to 97 % (at metering pressure and temperature conditions). A two inch MPFM-301 was tested at Texaco's Humble Flow Facility over a range of methane gas, crude oil, and water flow rates. The test conditions included:

multiphase flow streams with meter inlet gas fractions from 2 to 93%single phase flow streams,inlet volumetric rates from 9 to 120gpm (309 - 4,114 BBL/D)water cuts from 0 to 100 % andthree different inlet piping configurations to provide meter inlet test Streams short to long slug lengths

The MPFM 301 determines the oil, water, and gas rates via three stacked components: an oval gear meter, dual Venturi run, and a microwave-based water fraction monitor. The ovalgear meter on the tested two-inch meter limited the total inlet volumetric rate to 4526 bbl/d. The flow rate turndown for the MPFM-301 is over 20to1 at gas fractions between 30 and 40 %; the turndown decreases outside of this gas fraction range e.g., to 3.3 to1 at a gas fraction of 95% and to 1to1 at a gas fraction of 97%. Relatively speaking, the MPFM 301 has very small error specification for a multiphase flow meter. For the oil rate and for the water rate error specifications are the larger of 10 % of value and 2 % of full scale. For the gas rate the error specification is the larger of 10 % of value and 5 % of full scale.

Pressure fluctuations and possible inventory changes are presumed to be the cause of the differences between the MPFM-301 and loop measurements for the well configuration tests. Limited analysis indicates that inventory changes were probably not a significant cause. Pressure fluctuations may degrade the results in several ways One improvement intended for applications with pressure fluctuations, especially at relatively low pressures, is to have the gas rate reported at standard conditions rather than at actual conditions. This reporting change should be implemented in field production applications as well as in laboratory testing.

The MPFM-301 data showed no apparent correlation between gas fraction and accuracy of gas, oil, and water rates. Typically, the MPFM-301 oil rate errors were as large at very low oil rates as at higher oil rates - presumably this is due to the difficulties of determining oil fraction accurately with a multiphase measurement and a less then perfect gas fraction measurement.

The MPFM-301 did not show any signs of being fooled by the multiphase stream and consequently always reported reasonable oil, water, or gas flow rates.

Testimony #3 - From the NEL Test Report, September1995.

From the Report:"3.4 The meter performance was not affected by the salinity of the waterused in the tests. No influence of flow pattern or slug frequency was noted.The change between oil and water continuous phases did not influence themeter performance"

Testimony #4 - From the Agar MPFM Gosstandardperformance qualification testing, held at the ConocoMultiphase loop, February, 1996.

Testimony #5 - From SPE paper 36594, "Field tests of a high gas volume fraction multiphase meter" B. Tuss, SPE, Conoco, Inc.; D. Perry, Conoco, Inc.; G. Shoup, SPE, Amoco Corporation. October 1996.

"Tests were conducted during November, 1995 by Agar Corporation, Conoco, Inc., and Amoco Corporation at the Conoco Multiphase Test Facility near Lafayette, Louisiana, to demonstrate the performance of a novel high gas volume faction multiphase meter. This paper describes how the meter works, summarizes the results of these field tests and discusses the application of the flow meter."

"As noted by the plots in Figure 7 through 10, the meter can measure oil, water, gas and liquid rates of a multiphase stream within the accuracy specification stated in Table 1 under the very wide variety of flow conditions represented by the text matrix. Figure 11 shows the total (oil+water+gas) flow rates as determined by the meter to have an accuracy of about 2% of reading when compared with a reference test loop..."

Testimony #6 - From the Caltex (Indonesia) Newsletter, March 1997.

Every oil well must have historical data, like its capacity in producing oil along with gas and produced water. From these data, CPI can then discover accurately the characteristics of the oil well, including its oil type and its reserve.To get data of the oil well performances, CPI is using an instrument called Micro‑motion. Using this instrument, well testing is carried out through two or three‑phase separation processes. The two‑phase separation is the separation of production fluids into gas and liquid, whereas the three‑phase is the separation of production fluids into the elements of oil, water, and gas.The well testing finishes as the three fluid elements ‑ oil, water, and gas ‑ are measured according to their currents and flows. From these measurements, people can calculate the capacity of the oil well in producing crude. If water is produced more than the usual, it means that the well has a problem."Being equipped with such data, Well Services team can immediately go to the fields and fix the problem so that oil well production can be reoptimized," said Ary Yunianto, Design & Construction Engineer from Bekasap SBU.Considering the importance of testing device, CPI feels it necessary to get the latest device of the more sophisticated technology to replace the Micro‑motion instrument. The new device is called multi‑phase flow meter (MPFM), which, since March 1996, has undergone its trial use in the Bekasap oil field."The result is quite satisfactory. Beside its magnificent speed, the new instrument can give CPI the performance data of an oil well more accurately. In its operation, MPFM measures the current and flow of oil, water, and gas without separation processes," expressed Dhani Satria Dharma, Design and Construction Engineer from Bekasap SBU.CPI has currently installed four MPFM facilities, three units at the Bekasap gathering station and one at Aman oil field test station. It is planned that due to their satisfactory results, CPI will use the new devices in the Bekasap oil field area, where production is presently optimized by means of water injection technology.To make these devices effective, Design & Construction ‑ Bekasap AMT has trained its field operators so that they have basic knowledge on how to operate and maintain these well testing facilities."After attending the training, the operators are expected to be able to operate MPFM units appropriately and in case of any disorder, they can manage the problem in the earliest possible way," revealed Dhani."

Testimony #7 - An article from Maraven's (currently, PDVSA) newsletter, August 1997.

A multi-phase flow meter -New technology for well testingIn order to optimize its production operations, Maraven, through its Production Technology Department, with Intevep's support, started a multi-phase flow meter for high gas void fractions (GVF) and high gas/oil ratios (GOR) in Barua V Flow Station, located in DOP's Barua-Motatan field, as an alternative to traditional well testing system.Emilio Guevara, Production Technology Fluid Management Superintendent, stated that the flow meter, Agar MPFM-400, for high gas void fractions is capable of measuring gas contents as high as 99.9% and is an extension of Agar MPFM-300 series (limited to a maximum of 97.5% gas) to which has been added a flow diverter . This diverter, using the difference in momentum between phases, diverts most of the free gas in the multi-phase stream (oil-water-gas) towards a bypass, whilst the remaining portion continues through the multi-phase flow meter. The gas is measured in the bypass line before it is combined again to the mainstream at the MPFM-300 outlet where total gas, oil and water are computed.Both gas portions are added and the result is a meter capable of measuring gas-dominant flow streams with an accuracy of +/-10% of relative error and whose results appear in the screen as shown in the figure. This approach extends the measuring range, especially for the GOR, and reduces costs eliminating the need of a bigger unit. The meter is currently under evaluation in Barua V flow station and is connected in series with the test separator. Results to date are satisfactory, demonstrating once more, the equipment versatility as a substitute to well testing separator. Unlike it, the MPFM measures simultaneously and in real time, each phase flow (oil, water and gas). In the table shown, an example of performed measurements is presented.The use of this technology in future developments is important since it reduces space and costs (inversion/operation), improves well test (more representative data and shorter test times/costs), which is important for Reservoir, Production and Operations Departments. Real time data allows a more efficient and continuous remote supervision, thus reducing deferred production due to failures. It is important to emphasize also that, for performing a particular well test, this meter does not require fluid characterization (API gravity, gas or crude oil composition, viscosity, water cut, salinity).Economic feasibility studies, based upon conventional systems (test separator and heater) have demonstrated it is possible to save up to 35%, depending on application and field conditions.

37

Testimony #8 - From SPE paper 38784, "Performance Test of a High Gas Volume Fraction Multiphase Meter in a producing Field", Charles C. Ngai, SPE, Michael D. Brown, Pan Canadian Petroleum Ltd.., Parviz Medizadeh, SPE, Consultant. September 1997.

"A high gas volume fraction multiphase flow meter was installed and tested in PanCanadian Petroleum Ltd.. Rockford Battery. The performance testing was conducted from June 1996 to September 1996. This paper describes the the multiphase meter, the battery well test facility and test results of a high gas volume fraction multiphase meter in a producing field...Over 50 well tests from 7 producing wells were measured with a water oil ratio (WOR) range from 0-96.2% and a gas oil ratio (GOR) range from 41 to 284 m3/m3. Maximum average gas volume fraction encountered in these tests was 96.6%.Test results showed excellent agreement between the multiphase meter and the well test facility. The MPFM-401-20-20 met all its manufacturer's specified accuracies. The meter also showed its real time diagnostic capability for producing wells. It demonstrated the flow characteristics of a horizontal well at different draw downs. The real time data collected was analyzed and used to optimize the well and troubleshoot the artificial lift equipment.

As illustrated in the plots, the measurement of oil, water and gas by the test meter were well within the specifications...For water cut, the accuracy was well within 5%..."

Testimony #9 - From an acceptance test report written by Wayne Lake, an Amoco

instrumentation specialist, January 1998.

"Test Overview. The subject meter was tested/witnessed on 10/3/97 at EnFab’s facility in Houston, Texas. EnFab does not have a multiphase calibration loop so Agar purchased/rented and installed compressors, coolers, pumps and meters for a variable rate, air/water multiphase flow test facility to cover the specified range of the meter and reportedly GUPCO’s gas lift applications. The test grid roughly covered 0-120 psi, 500-3500 BPD of water and 100-600 MACFD of air. The reference meters consisted of a bank of four vortex shedding devices for air and a Brooks Oval gear meter for water. The estimated uncertainty of the reference meters is approximately < +/- 1 % for water and < +/- 2 % for air.

Test Results. The one minute averages from the Agar MPFM tracked the reference meters well within the specifications after a system stabilization period for gas fractions up to 99.6 %. The maximum pressure drop observed was 5-6 psi."

Testimony #10 - From "The use of a multiphase Flow Meter to optimize Gas Lift Well Operations" by Dr. Atef A/Allah A/Hady, Production Division Manager, Gulf of Suez Petroleum Co. Presented at the "Multiphase Metering for Offshore Production", IBC Conference, held in Houston, Texas, March 1998.

"This paper will discuss the use of a multiphase flow meter to optimize gas lift field operations. In particular, it will compare analysis methods for individual well’s performance using an Agar Multiphase Flow Meter versus standard nodal analysis. It will cover Gupco’s field experience with the Agar MPFM-401.

For many years the industry standard for gas lift well optimization was based on nodal analysis using field-proven flowing pressure correlation for vertical and horizontal flow. In almost all cases, it has been impossible to accurately make the predicated model results match the reported well test data, or obtain a material balance for the field. This has occurred chiefly because of the inability to obtain accurate and repeatable well test results using standard testing methods. The time required to test and analyze an individual well was restricted, since the test separator is normally in use and dedicated to standard field operations. By using a multiphase flow meter, Gupco’s engineers were able to obtain accurate real time data of well production and review the effects of changing the operating parameters of an individual well. By using the data acquired, not only were the operators able to achieve better results in individual well performance, but they were also able to approach a material balance for field production. The use of a multiphase flow meter allowed Gupco to overcome the problems outlined above.

To use a multiphase flow meter for optimization, Gupco first had to consider the required operating characteristics of such a meter. Gupco needed a meter that would be accurate and easily transported between individual wells. The meter was also not to be affected by changes in fluid properties such as density or salinity . It was imperative to choose a meter that was capable of handling high gas volume fractions, as large as 99%, since gas lift wells fall under this category. The meter was also to accurately measure in all flow regimens. This is due to the fact that gas lift wells generally present the entire spectrum of flow regimes in pipes. Gupco had several choices of commercially available multiphase flow meters, yet our choice was the Agar MPFM-401, as it was the only meter that could match our desired operating guidelines."

Testimony #11 - From SPE paper # 49161 "Field Trial of a Multiphase Flowmeter", Peria G. Mohamed, SPE; Kaled H. Al Saif, SPE, Kuwait Oil Company, September 1998, and from the field test final report.

A Multiphase Flowmeter (MPFM) was installed in series with a conventional well testing system (test separators and test tank) in an operating field in Kuwait. The MPFM employs a positive displacement meter, a venturimeter and a microwave meter to measure the flow of total fluid, gas and water respectively. A bypass loop with a vortex shedding flowmeter enables measurement of a large range of gas flow rate. A number of wells covering a wide range of Production rate (680 to 6130 bpd), Gas Oil Ratio (207 to 889) and water cut (0-65%) were tested. The comparative results are presented. The MPFM results are more accurate, more repeatable than those of conventional system and allows faster well testing. An insight into the behavior of MPFM at varying field conditions and useful information on issues related to range and accuracy are presented. Useful hints to those companies interested in testing/procuring Multiphase Flowmeters are also presented.Conclusions:The MPFM was field tested over wide range of Production rate (680 to 6130 bpd), Gas Oil Ratio (207 to 889) and water cut (0-65%). The average errors in liquid production rate and gas rate for 32 tests are 5.84% and 7.5% respectively. It provides more accurate and more consistent results than conventional measurement (reference)."Recommendations:It is recommended to procure the AGAR MPFM due to the following reasons:1. It meets the guaranteed performance accuracy (see section V1(2)iv.c for reasons or apparent deviations).2. It provides more accurate and more consistent readings than KOC's existing measurement system.3. The results are obtainable on-line and the well tests can be completed in a short time. Though one hour tests are possible, it is suggested that well tests are done for 2 hours duration. Thus, in a day, 6 wells can be easily tested (if flowline conditions permit).4. On-line monitoring of water-cut and gas will be helpful in better management of high water-cut and high gas producing wells (i.e. due to better understanding of the effect of choke size on water-cut and gas).

. . . This approach extends the overall measurement range, especially for high GOR wells and reduces the overall costs since it eliminates the need for a larger unit.. . . without the need for any input by the operator on fluid properties such as density or salinity.. . . the algebraic average error is 1.4%, since positive deviations and negative deviations cancel each other to provide low net error.… The AGAR MPFM was able to detect the leakages through the test header due to bypassing of valves. . . …The MPFM is very user friendly. Any Operator can be trained in a matter of a few hours

Testimony #12 - From "Multiphase Flow Metering Experience in the Venezuelan Oil industry" by Aaron Padron and Emilio Guevara. Presented at the 7th Unitar International Conference on Heavy crude and Tar Sands. February 1999

"FLUID PROPERTIES AND TEST CONDITIONS° FLUID PROPERTIESCRUDE OIL °API Gravity 9.3 to 15.8 °C - Viscosity 20 Pa.s to 38 °C -1 to 5 % Water cutPRODUCED WATER NaCl content range of 5000 to 9000 ppm GAS Specific Gravity 0.623 - 93% methane 6% CO2

° TEST CONDITIONS TEMPERATURE 60 to 84 ° C OIL VISCOSITY 0.2 to 20 Pas GOR 5.5 to 44.5 m3/m3 WATER CUT 0 to 100% SALINITY 100 to 20000 ppm

CONCLUSIONS:THE 301 MULTIPHASE METER PERFORMANCE DURING THE TEST PROGRAM CONDUCTED WITH EXTRA HEAVY OIL, SHOWED THAT IT IS A VIABLE ALTERNATIVE FOR CRUDE OIL WITH SO LOW API GRAVITY IT HAS BEEN ABLE TO MEASURE THE INDIVIDUAL OIL, WATER AND GAS FLOW RATE WITHIN THE ACCURACY OF 10% (RELATIVE ERROR)

GOOD PERFORMANCE WAS SHOWED WHEN HEAVY OIL IS COMING FROM STEAM INJECTION PROCESS

MULTIPHASE METERING FOR HIGH GAS VOLUME FRACTION COULD BE OBTAINED, BY PARCIAL SEPARATION AND MEASUREMENT OF THE GAS.

MULTIPHASE METERING FOR HEAVY AND EXTRAHEAVY CRUDE OIL IS COMMERCIALY AVAILABLE

Petrozuata C.A.Av.. Intercomunal Adrés BelloSector Las Garzas, Centro Comercial MT, Piso 2.Puerto La Cruz, Estado Anzoátequi, VenezuelaTelf.: +(58) 081.80.7001Fax: +(58) 081.80.7010

Testimony #13 - A letter by Petrozuata's Lead Project Engineer, December, 1999

Jess D. McConnellLeader - Project EngineeringProduction Technical ServicesJess.McConnell@Petrozuata.com

Agar CorporationAttention: Jo Agar (joagar@attglobel.net)Subject: Agar MPFM 300 PerformanceJo, Per our conversation, I would like to make the following comments regarding the Agar MPFM 300 meters that are in service within our Zuata field near San Diego de Cabrutica, Venezuela:We are currently using the Agar MPFM 300 meter for well performance and production allocation measurements. We received our first meter in February 1998. At this writing, have over a year of operating history with the MPFM 300 meters in a variety of well conditions.

The measured fluid is an extra-heavy crude (8-9 API) and diluent (currently a 30 API crude) blended to 16 API. Gas varies from 100 to over 200 GOR.

23 meters have been placed in service to date. A total of 33 meters have been purchased. Meter accuracy is consistent with the manufacturer’s specifications and Petrozuata design expectations.

Meter performance has been independently verified in both controlled and field operating conditions. Agar has actively supported testing and meter optimization for our service .

Petrozuata currently maintains a good working relationship with Agar Corporation and appreciates the time and effort that has been involved in advancing this project. Please let me know if I can be of any additional service.

Sincerely,

Appendix - B

Spe Paper 36593

Annual SPE, October 1996, Denver, ColoradoA.M. Scheers and W.F.J. Slijkerman,Shell International Exploration and Production B.V. - Research and Technical Services, The Netherlands

...Accuracy considerations. The uncertainty in the phase fraction calculation is due to the statistical behavior of the radioactive decay. It can be demonstrated that the absolute uncertainty in the oil fraction, compared to those of water and gas fractions, is always largest (Ref. 11).It is also obvious that the maximum absolute uncertainty in oil fraction occurs with the lowest count rate, e.g. with 100% of saline water. Influence of Fluid Properties. The 100% water reference count rates for the lower energies, as required in the DEGRA calibration, are strongly dependent on the salinity of the production water. This is because salt has a higher absorption coefficient compared to water. Systematic errors in the measured water, oil and gas fractions will occur if the salinity of the production water changes and the 100% water reference count rate is not corrected. In many potential multiphase metering applications, the salinity of the production water will indeed vary in time and it might also be different for each well drilled in the same reservoir. In water-injection reservoirs, for example, the salinity will change from formation water salinity to injection-water salinity. It should be noted that the problem of salinity changes is not unique to the gamma ray absorption technique.Also conductivity measurement techniques, often used in situations of water external emulsions, are influenced by salinity changes. (Ref. 13).

Excerpts from SPE 36593 Multiphase Flow Measurement Using Multiple Energy Gamma Ray Absorption (MEGRA) Composition Measurement

Fig, 8 the relative changes in watercut (watercut/watercut) are indicated for a change in salinity of 10 kg/m3

away from the calibration saline. In this example, at a 50 kg/rn3 salinity and a salinity change of 10 kg/m3

result in a (watercut/watercut) of 8%. At a watercut level of 50% this equals a 4% absolute error in watercut and an 8% relative error in net oil production.

The curve in Fig. 8 is almost independent of the energy levels used. Multiphase meters using a Barium-133 source (30 and 360 KeV) or a combination of Am-241 and Cesiurn-137 sources (60 KeV and 660 KeV) will suffer from the same errors in watercut due to a change in salinity.

Fig, 7 the production water salinity for the wells of a North the Sea reservoir are shown as measured in January and June 1993. It not only shows that salinity is different for each well in the same reservoir, but also that in a 6 months period the concentration varied. Salinity for some wells has changed by more than 10 kg/m 3. Also horizontal and/or vertical gradients in formation water be salinity across the reservoir may occur. Ref. 12 presents an example where such gradients can lead to salinity variations much larger than 10 kg/rn3