SPE 114191

Comparative Analysis of Production Method with PCP Systems at Rubiales Oil Field (Colombia) C.A Rubio, and P.A Agudelo, Weatherford Colombia Limited; and J.E Peñaloza, Meta Petroleum Limited

Copyright 2008, Society of Petroleum Engineers This paper was prepared for presentation at the 2008 SPE Progressing Cavity Pump Conference held in Houston, Texas, U.S.A., 27–29 April 2008. 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 Rubiales is an oil field located into Llanos Orientales Basin (Colombia) where was installed first PCP system in 2003, artificial lift method by means of which the development of this field began. At the present time, the production is shared with another artificial lift method: electrosumersible pumping and in this study appears the operative and reservoir comparison of the historical production behavior of this field. From their beginning in Rubiales field there were 23 wells with PCP Systems of which today in day prevail 12 of them with tendency to increase (new prospects to drill) operating under normal conditions of production, represented in the most stable fraction of the total volume of recovered petroleum with respect to the comparison mentioned in the previous paragraph because the behavior of wells with PCP system has maintained the tendency with the time, phenomenon totally opposed to the one of wells with ESP system. This oilfield produces heavy oil (12,3 °API @ 60 °F) with high water cut (Rubiales’ average BS&W = 81%) in emulsion state, which to the being conjugated with non extreme operation conditions and “ideal” well geometries, indirectly has allowed the excellent performance of PCP systems, because have not been had any problems or faults associated with bottom components. In this study precise well comparisons will appear such as, RB-31 (PCP) and RB-45 (ESP) to show analytically the advantages and disadvantages of a system as opposed to the other, analyzing even the demand of power and the cost of each one of them from the description of each one of their components, emphasizing in the typical configuration of the systems PCP that are had in the field. Finally it is added that Rubiales case is considered important to share in the industry because can be used like departure point or comparative parameter for the selection and application of artificial lift methods in similar fields. Rubiales is an oil field located into Llanos Orientales Basin (Colombia) where was installed first PCP system in 2003, artificial lift method by means of which the development of this field began. At the present time, the production is shared with another artificial lift method: electrosumersible pumping and in this study appears the operative and reservoir comparison of the historical production behavior of this field. Today in day there are 14 wells with PCP Systems with tendency to increase (new prospects to drill) operating under normal conditions of production, represented in the most stable fraction of the total volume of recovered petroleum with respect to the comparison mentioned in the previous paragraph, because the behavior of wells with PCP system has maintained the tendency with the time, phenomenon totally opposed to the one of wells with ESP system. This oilfield produces heavy oil (12,3 °API @ 60 °F) with high water cut (Rubiales’ average BS&W = 81%) in emulsion state, which to the being conjugated with non extreme operation conditions and “ideal” well geometries, indirectly has allowed the excellent performance of PCP systems, because have not been had any problems or faults associated with bottom components.

2 SPE 114191

In this study precise well comparisons will appear such as, RB-31 (PCP) and RB-45 (ESP) to show analytically advantages and disadvantages of a system as opposed to the other, analyzing even the power demand and the cost of each one of them from the description of each one of their components, emphasizing in the typical configuration of the systems PCP that are had in the field. To finish, Rubiales case is considered important to share in the industry because can be used like departure point or comparative parameter for the selection and application of artificial lift methods in similar fields. Introduction At Rubiales oil field the production started with PCP systems but with the pass of the time were installed ESP systems like other production method that permit reach high volumes. Both methods have had good behavior and results, though there are designed for different operation conditions and well sceneries (5). Here it’ll be shown a comparison of these artificial lift systems to remark PCP benefits focused in the potency requirements and costs, BS&W tendency and run life. To reach this objective RB-31 and RB-45 will be the main case to comparison but at the same time will be mentioned other wells like RB-47 to act as a guide to explain this affirmation. In next section will be find generalities, operation and production conditions of Rubiales oil field to prepare the ambient to understand why is shared this case into oil industry. Statement of Theory and Definitions Here appear the main concepts and definitions that will be involved in the study and will let complain its sense. They are the following terms: Progressive Cavity Pump (PCP): The PCP is a positive displacement pump type (composed by a rotor and a stator with different number of stages) that can be used to pump a wide range of multiphase mixtures, including high viscosity fluids with entrained gas and solid particles in suspension (1). However, PCP has a reduced ability to handle high gas-liquid ratio due to limitations of its elastomeric stator material required to overcome thermo and mechanical effects. These pumps constitute an artificial lift method applied in oil industry to recover hydrocarbon fluids. Electric Submersible Pump (ESP): An artificial-lift system that utilizes a downhole pumping system that is electrically driven. The pump typically comprises several staged centrifugal pump sections that can be specifically configured to suit the production and wellbore characteristics of a given application. Electrical submersible pump systems are a common artificial-lift method, providing flexibility over a range of sizes and output flow capacities (2). BS&W: Abbreviation for basic sediment and water. BS&W is measured from a liquid sample of the production stream. It includes free water, sediment and emulsion and is measured as a volume percentage of the production stream (2). Voltage and Current: Voltage is the force, or pressure, of electricity also known as "electric potential". "Voltage drop" is the difference in voltage from one end of an electrical circuit to the other. For instructional purposes, voltage is often compared to water pressure and current is the flow of electrons through a circuit. Voltage is measured in volts and current in amperes (3). Electric Power: is the product of voltage and current and is measured in KW or KVA so, this way (3):

10000732,1**avgCurrentavgVoltage

KVA =

85,0*KVAKW = Where 0,85 is an power factor used to power and electric generators.

Run Life: Is the expected time to operate any equipment without presence of irreversible failures. It depends of its reliability, while this equipment is working under determined operation conditions according its design (4).

SPE 114191 3

Rubiales Background and Generalities Rubiales is an oil field located in Llanos Orientales Basin (Colombia) and produces from a meander reservoir of which properties are shown in table 1.

Gacheta Formation (sea origin)Age: Upper Cretaceous

Trap and Migration ProcessesFrom Llanos Orientales Basin to Westregion. (Carbonera Formation ontoPaleozoic)

ReservoirCarbonera Formation (mono and polycrystalline quartz and potasiumfeldespates)

Porosity (%) 25 - 32Permeability (darcys) 5 - 50 Production thickness (feet) 10 - 80

Source Rock

Table 1: Rubiales Reservoir Properties

At the moment there are some wells completed and producing with PCP systems, all of these with a simple completion and similar features like are shown in figure 1. In the same way there are other wells with ESP but different that PCP wells, these are horizontal or directional completions and have several models of this kind of artificial lift method due the volumetric capacities selected for the oil field. In figure 1 appear these two possiblities of completion in their typical configuration at Rubiales.

Figure 1: Typical Configurations Wells – PCP & ESP Systems

Average field BS&W is 81%, but all wells are in a range between 25% and 94%. The fluid produced is biphasic because is composed by heavy oil and fresh water (without gas presence), of which properties are shown in table 2.

4 SPE 114191

State LiquidWater Solubility NoneAutoignition Point 405 ºCSpecific Gravity @ 60 ºF 0,9843Vapor Pressure @ 68 ºF 0,89 psin-C7 Insoluble 13,17 %mAshes 0,04 %mCinematic Viscosity @ 150 ºF 367,8 cStGross Combustion Heat 43,199 MJ/KgHydrogen Sulfur < 3 (3 ppm wt)Color BlackInflammation Point 180,86 ºFAPI Gravity @ 60 ºF 12,3 ºAPINeutralization Number 0,45 mg KOH/grFluency Point + 50 ºFCoal Residue - Ramsbottom Neat 12,6 %m

Alcalinity 835 ppm CaCO3Chlorides 164 ppm Cl-Conductivity 1381µΩ/cmTotal hardness 23 ppm CaCO3Iron 0,09 ppm Fe+3pH 7,4Solids in Suspension 2336

OIL

WATER

Table 2: Rubiales Fluid Properties

From 2003 till to date, Rubiales have been operated by the same company (Meta Petroleum Limited) and the production growing has been fast and important to Colombian oil industry goal owing to selection and installation of these two kind of artificial lift systems. In figure 2 it can see this growing that passed from 6.000 BOPD in 2004 to almost 30.000 BOPD today, in 2008.

RUBIALES HISTORICAL BEHAVIOR OF OIL PRODUCTION

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OPD

) Production drop duemeteorologic contingence

Figure 2: Historical Behavior of Oil Production of Rubiales Oilfield

The production has gotten growing and its distribution is shown in the following Pareto’s diagram which can see all wells of Rubiales oilfield and the tendency at the present. (Figure 3)

SPE 114191 5

PARETO DIAGRAM - OIL PRODUCTION

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-63

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PD

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PRODUCTION FORECAST RUBIALES OIL FIELD

29,292 BOPD

80% OIL PRODUCTION 23,197 BOPD

20% OIL PRODUCTION 6,095

PCP Systems Wells

Figure 3: Pareto Diagram – Oil Production of Rubiales Oilfied

At the present Rubiales oilfield produces almost 30.000 bopd and 75.000 bwpd and there are 33 wells in production of which 9 of them have PCP systems and 24 ESP systems. This distribution in fraction volume terms (oil production) means that with ESP corresponds to 95% and 5% remaining to PCP. Maybe this small volume comparison can be very drastic but in terms of power requirements and stable conditions of production (mainly BS&W) permit see the advantages of PCP vs ESP systems, situation that is presented in the last part of this document. To this year is expected reach to complete 35 additional wells: 12 to be completed with PCP and 23 with ESP to produce 60.000 bopd. PCP at Rubiales Oil Field From their beginning (2003) in Rubiales field there were 23 wells with PCP Systems of which today in day prevail eight of them and one completed last year (nine in total), operating under stable production conditions represented in a small volume portion of total recovered crude volume at oil field. Some of these conditions are for example, torque, water cut (BS&W %) and fluid levels of the wells, all them features that helping reservoir production mechanism. These wells are producing fluids under the following conditions, shown in the below table (table 3):

6 SPE 114191

RB-10 RB-30 RB-31 RB-33 RB-37 RB-38 RB-39 RB-41 RB-80Velocity (RPM) 190 130 60 255 92 220 205 200 70Torque (%) 67 35 95 76 93 69 33 67 18Middle Point of Perforations (feet) 2634 2630 2938 2657 2660 2657 2693 2621 2600Pump Intake Depth (feet) 2421 2403 2574 2393 2487 2440 2430 2426 2457Total Liquid Column (feet) 900 1787 234 804 218 1072 1816 1207 2188Depth of Level (feet) 1521 616 2340 1589 2269 1368 614 1219 269BFPD (Barrels of Fluid per Day) 1029 633 299 1244 422 1175 809 1047 257BS&W (%) 83 87 30 65 72 80 80 75 90BOPD (Barrels of Oil per Day) 175 82 209 435 118 235 162 262 26Volumetric Efficiency (%) 97 88 90 88 83 97 71 90 63PIP (psi) 384 762 100 343 93 457 775 515 933PWF (psi) 475 859 255 456 167 550 887 598 994

Table 3: Operation Parameters of PCP Systems Wells During all run life of these systems, they are operated under moderate conditions that are allowed keep the natural bottom properties to generate low drawdown in the reservoir and at the same time, permit to lift a constant oil volume along the time. These PCP’s are operating with low velocities (maximum value: 255 rpm) always analyzing reservoir response, behavior represented in BS&W tendency and constant dynamic fluid levels during long periods of time (always keeping more than 200 feet of submergence), having in account that all these wells are vertical completions. As was shown in the figure 1, PCP typical completion for this field is very simple. All systems are composed by pumps with NBRA elastomer that displace 5 bfpd/rpm with sucker rod string without centralizers’ elements and drivehead with electric motor. They are operating under moderates velocities and for this reason is possible to think that the drawdown of these wells have been obviously lower than the produced for ESP systems. This affirmation can be supported with the BS&W tendency keeping with the time because all of these wells have had increments “soft” and slow along the time permitting have a stable portion of oil volume produced during last years. In figure 4 are shown the tendencies of BS&W of these wells in function with the time to can have an idea of the reservoir’s response for this stimulus.

BS&W BEHAVIOR - PCP WELLS RUBIALES OIL FIELD

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28-Jun-03 14-Ene-04 01-Ago-04 17-Feb-05 05-Sep-05 24-Mar-06 10-Oct-06 28-Abr-07 14-Nov-07 01-Jun-08

Date

BSW

(%)

RB-30 RB-33 RB-37 RB-38 RB-41

Lineal tendency with asoft slope. Stableconditions along the time

Figure 4: BS&W Behavior – PCP Wells Rubiales Oil Field

SPE 114191 7

Additionally, it’s pertinent to emphasize the PCP operation behavior related with torque and run life, two properties that have contributed with the no failures occurrence in bottom, due at the same time to fluid levels of the wells and submergence of the pumps that permit “moderate” equipment operation as was mentioned previously. ESP at Rubiales Oil Field After to start and keep all production with PCP systems was decided to include other artificial lift system at oil field: Electric Submersible Pumps. The reason for this decision was the production goal of Operator Company and the first installation with ESP to try to reach this target was: RB-23 well. The results were satisfactory and after continued some wells step by step to reach 24 ESP completed wells operating to date. In the following table appear the operation conditions of these wells (table 4).

RB-04 RB-025 RB-042H RB-043D RB-044D RB-045H RB-047 RB-048H RB-051 RB-054H RB-055H RB-057HFrecuency (Hz) 36 56 46 44 36 52 38 56 59 51 50 41

Total Liquid Column (feet) 1940 1291 2023 1083 381 2090 393 1455 309 1464 1641 961

Depth of Level (feet) 751 1244 927 2024 2870 1174 2038 1857 2101 1127 1462 2064BFPD (Barrels of Fluid per Day) 2614 4537 8600 4774 234 8844 282 7958 479 8160 9990 4952

BS&W (%) 88 85 84 84 71 88 42 89 32 85 84 86BOPD (Barrels of Oil per Day) 314 681 1376 764 68 1061 164 875 326 1224 1598 693

PIP (psi) 840 559 863 469 165 905 170 630 134 917 700 410

RB-058H RB-059H RB-060H RB-061H RB-062H RB-063H RB-064H RB-065H RB-066H RB-067H RB-068H RB-075HFrecuency (Hz) 55 43 37 44 44 42 38 45 39 39 38 39

Total Liquid Column (feet) 1166 1411 2218 1625 1686 1735 1873 1161 1222 1280 1734 1947

Depth of Level (feet) 1842 1731 639 1070 1110 1128 1088 1709 1634 1345 1056 853BFPD (Barrels of Fluid per Day) 7374 4508 5058 5171 7760 6416 7555 3450 2549 1966 2334 1685

BS&W (%) 65 83 84 46 82 39 84 43 81 27 55 14BOPD (Barrels of Oil per Day) 2581 766 809 2792 1397 3914 1209 1967 484 1435 1050 1449

PIP (psi) 505 602 946 693 719 740 799 495 521 546 740 830 Table 4: Operation Parameters of ESP Systems Wells

To difference of PCP completions, all ESP’s are installed into directional or horizontal wells, geometry that contributes to ensure better fluid inflow from reservoir, having the production zones in deviated sections. At Rubiales oilfield there are some models of these systems. Mainly there are pumps to displace volumes from 3.000 to 10.000 bfpd, with different kinds of bottom configuration and number of stages and power requirements from 200 to 700 KVA. However, there are some wells like RB-44D, RB-47 and RB-51 that not have had a good response form reservoir and have been necessary operate them under low frequencies conditions (average: 35 Hz) to warrant Pip values upper 100 psi to keep the integrity of these equipments. Additionally is good to mention that due the high power of this kind of artificial lift method, the drawdown generates in bottom is high and for this reason BS&W behavior for these wells has had a strong tendency to increase into short time periods. The result of this phenomenon is to have in surface high water volumes in comparison with oil recovered volumes, because reservoir’s water inflow is very active. In figure 5 it can see this tendency, showing some of ESP Systems wells that operate today.

8 SPE 114191

BS&W BEHAVIOR - ESP WELLS RUBIALES OIL FIELD

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18-Ene-07 09-Mar-07 28-Abr-07 17-Jun-07 06-Ago-07 25-Sep-07 14-Nov-07 03-Ene-08 22-Feb-08

Date

BSW

(%)

RB-54H RB-60H RB-62H RB-64H

Strong slope inBS&W tendency

Figure 5: BS&W Behavior – ESP Wells Rubiales Oil Field

Comparison: PCP vs ESP Systems After of mention the main features of Rubiales oilfield and explain all operation conditions of their wells it’s necessary to select two of them to can develop the comparison that constitute the main objective of this article. These wells are RB-31 with PCP and RB-45 with ESP. RB-31 was completed and started its production on November of 2003. In that moment had 5% of BS&W, value kept during a period around 18 months, moment which this condition changed after organic treatment application to reach to date BS&W values of 25% in average. During its life, this well has been operated under different conditions, but in average with 100 rpm due its dynamic fluid level behavior. In this well from beginning has had precipitated asphaltens and/or deposited paraffin wax on borehole, situation that difficults or blocks natural inflow to act as an obstacle. However, under this operation velocity is had kept a submergence for the pump around 100 feet to avoid any damage in bottom equipment and in the same time, recovering a significant oil volume taking in account the BS&W values (200 – 500 bopd). RB-45 was completed and started its production on August of 2006. In that moment had 20% of BS&W, value that was increasing of regular manner with the pass of the time. In February of 2007 this property reached values around 75% and today is near to 90%. During its life, this well has been operated under normal conditions because always has kept the Pip in high values (upper than 500 psi). Of this manner to operate the system, today have been recovered 1.000 bopd (average).

SPE 114191 9

In the following picture (figure 6) is shown this comparison letting analyze the drawdown generated in each case.

BSW Behavior - RB-31 and RB-45 Wells

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W

RB-31 RB - 45

Shut off due meteorological contingence (june 2007)

16 months keeping the "same"value of BS&W

Fastly increase of BS&Wtendency (3 months approx.)

Skin on wellbore dueorganic treatment

Figure 6: BS&W Behavior – RB-31 and RB-45 Wells

Like RB-31 and RB-45 are different, is good to mention other ESP case that can be compared with RB-31. This case could be RB-47 which today operates @ 36 Hz, frequency under which it’s recovered around 290 BFPD. This frequency is associated to Pip conditions, which not permit increase this variable due that its values are low (average: 200 psi). Moreover along production history of this well BS&W behavior increased till 50% (but in variable manner) reason for which is important try to keep this parameter with a constant tendency. However if it’s analyze two cases from their beginning, it can see that drawdown generated by PCP installed at RB-31 is lower than drawdown generated by ESP of RB-47, because in second case in a period lower than one year BS&W increased from 10% to 57%, range bigger than the obtained in RB-31 case. In the following picture it’s shown RB-47 behavior where can find the moments which changed BS&W and the tendency of production conditions (figure 7).

10 SPE 114191

FREQUENCY VS BS&W - RB-47 WELL

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W (%

) -

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Q (H

z)

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D-B

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IP

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BOPD PIP

BS&W Tendency during 2006

Figure 7: Frequency vs BS&W RB-47 Well

Power Requirements A factor that is not mentioned along this document is the power requirements. At Rubiales oilfield the power generation is obtained by electric generators and in each well or cluster (place where there are many completed wells) there is one or some to supply the requirements of the systems installed there. All these generators need a diesel tank and the volume corresponding to each one. ESP systems require more power than PCP systems, due to electric components in bottom. Here, if it’s compared RB-31 vs RB-47 or RB-45 can be applied the simple equation shown in the first part of this document to calculate this requirement. To be continued appear the tables which are diesel requirements to ESP and PCP systems, remarked RB-47 and RB-31 respectively (tables 5 and 6):

ENGINE MODELNOMINAL

KVA PRIME MODE

NOMINAL KW PRIME

MODE

A-B B-C A-C A B CRB-025 55,0 NT855-G6 313 250 472 471 471 148 149 148 121,1 102,93 41,17 34,70 219,99 4491,6 82,43 789,17

RB-042H 45,0 NT855-G6 313 250 482 482 482 276 276 276 230,4 195,85 78,34 57,44 364,22 8359,9 83,33 1393,60RB-043D 41,0 NT855-G6 313 250 474 474 475 117 118 118 96,7 82,17 32,87 29,61 187,77 3913 85,76 557,21RB-044D 35,0 NT855-G6 313 250 474 475 475 60 60 62 49,9 42,39 16,96 19,88 126,04 241,5 74,62 61,29RB-045H 51,0 NT855-G6 313 250 474 475 475 187 190 191 155,7 132,31 52,92 41,89 265,60 8667 86,21 1195,18RB-047 36,0 NT855-G6 313 250 473 473 472 41 43 42 34,4 29,23 11,69 16,65 105,60 290,2 41,15 170,78

RB-048H 56,0 NT855-G6 313 250 472 472 472 247 246 246 201,4 171,17 68,47 51,40 325,92 7993,9 83,05 1354,97RB-055 49,0 NT855-G6 313 250 477 477 477 296 296 296 244,5 207,86 83,15 60,38 382,87 9749,3 83,04 1653,48RB-056 45,0 NT855-G6 313 250 462 462 463 138 142 144 113,2 96,20 38,48 33,05 209,55 7328,8 88,57 837,68RB-057 43,0 NT855-G6 313 250 478 478 478 250 250 250 207,0 175,93 70,37 52,57 333,30 5246,1 82,39 923,84

RB-060H 35,0 NT855-G6 313 250 479 479 479 110 110 110 91,3 77,57 31,03 28,49 180,64 4725 85,03 707,33RB-061H 38,0 NT855-G6 313 250 463 463 463 126 126 126 101,0 85,89 34,35 30,52 193,54 3395 30,26 2367,67RB-064H 38,0 NT855-G6 313 250 495 495 495 196 196 196 168,0 142,83 57,13 44,47 281,93 7601 88,27 891,60

CONS. DIESEL

(GAL/DAY)BFPD

DIESEL REQUIRED TO ESP SYSTEMS - RUBIALES OILFIELD

DIESEL CONS. BSW BOPDUSED %

LOADCONS. KVA

CONS. KWATT

SWELL Hz

PHASE VOLTAGE (VOLTS)

PHASE CURRENT (AMPERES)

Table 5: Diesel Requirements to ESP Systems

SPE 114191 11

POZO RPM´s ENGINE MODEL

NOMINAL KVA PRIME

MODE

NOMINAL KW PRIME MODE

INPUT VOLTAGE (VOLTS)

CURRENT (AMPERES)

CONS. KVA

CONS. KW

USED %LOAD

DIESEL CONS. (L/HR)

DIESEL CONS.

(GAL/DAY)BFPD BSW BOPD

RB-010 190 4BT3,9-G4 69 55 440 48 36,58 31,09 56,53 10,96 69,50 1028,1 81,11 194,21RB-030 130 4BT3,9-G4 69 55 479 29 24,06 20,45 37,18 8,41 53,31 646,4 88,29 75,69RB-031 60 4BT3,9-G4 69 55 461 51 40,72 34,61 62,93 11,81 74,86 298,5 31 205,97RB-033 255 4BT3,9-G4 69 55 450 41 31,96 27,16 49,39 10,02 63,52 1247,9 66,77 414,68RB-037 110 4BT3,9-G4 69 55 470 48 39,07 33,21 60,39 11,47 72,73 488,6 74,46 124,79RB-038 220 4BT3,9-G4 69 55 452 39 30,53 25,95 47,19 9,73 61,68 1121,5 72,46 308,86RB-039 205 4BT3,9-G4 69 55 452 27 21,14 17,97 32,67 7,81 49,53 788,8 80,85 151,06RB-041 220 4BT3,9-G4 69 55 452 38 29,75 25,29 45,98 9,57 60,67 1068,2 71,17 307,96RB-079 110 4BT3,9-G4 69 55 456 41 32,38 27,52 50,04 10,11 64,07 525,5 47,37 276,57

DIESEL REQUIREMENTS TO PCP SYSTEMS

Table 6: Diesel Requirements to PCP Systems

After these tables is easy to conclude that RB-47 is producing 290 bfpd with a diesel requirement of 105,6 gal/day (275 Kw power generator) and let think that for this well can apply a PCP system to displace this volume. Moreover, RB-31 well has an average production of 298 bfpd and its diesel requirement is 74 gal/day (60 Kw power generator). This affirmation invites to evaluate the artificial lift selection at Rubiales oilfield because RB-47 represents only one case where exist the possibility to re-design the completions thinking in save money, and to install simply equipment like PCP systems. Conclusions

PCP’s at Rubiales oilfield have permitted to keep the production conditions in the wells that have this kind of artificial lift system in comparison with ESP’s.

With PCP systems can ensure better production development of the wells and bigger productivity life of them. PCP completions are appropriate to be installed in horizontal or deviated wells with the Rubiales typical

configuration, according with completions of the present. At Rubiales oilfield there are some cases where it’s possible to re-evaluate the artificial lift selected. PCP and

ESP systems. To select a kind of artificial lift system it’s very important to analyze power requirements to ensure save costs

along the time. Acknowledgments Follow people and companies were very important to develop this study and their help was an incentive to finish it. Thanks to all: Meta Petroleum Limited, Rubiales oil field’s Operator Company. Eng. Iván Arévalo, Operations Manager. Eng. Diego Orozco, Drilling and Workover Manager. Eng. Arbey Rojas, Oil field Maintenance Coordinator. Eng. Jose Triana, Oil field Maintenance Coordinator. Weatherford Colombia Limited, current PCP Systems supplier at Rubiales oil field. Tech. Olimpo Silva, Field Operations Technician – PCP Group. SI Metric Conversion Factors

ºAPI 141.5 / (131.5+ºAPI) = g/cm3

bbl x 1.589873 E-01 = m3

cp x 1.0 * E+00 = mPa*s ft x 3.048 * E-01 = m ºF (ºF – 32)/1.8 = ºC in x 2.54 * E+00 = cm psi x 6.894757 * E+00 = kPa * Conversion factor is exact (8).

12 SPE 114191

References

1. Bratu, C.: “PCP Behavior in Multiphase Conditions”, paper SPE 95272 presented at the 2005 SPE Annual Technical Conference and Exhibition, Dallas, Oct. 9 – 12.

2. Schlumberger: “Oil field Glossary”, web site SLB.com. 3. Mac, C.: “Technician Glossary”, web site pcmag.com. 4. Speaks, S.: “Reliability and MTBF Overview”, Vicor Reliability Engineering, 2005. 5. Clegg, J.D. et al.: “Recommendations and Comparisons for Selecting Artificial – Lift Methods” SPEJPT (Dec.

1993) 1128. 6. Meta Petroleum Limited: All files of production history of Rubiales Oil Field. (Not cited in an special part of this

document).

Tables

1. Rubiales Reservoir Properties. 2. Rubiales Fluids Properties. 3. Operation Parameters of PCP Systems Wells. 4. Operation Parameters of ESP Systems Wells 5. Diesel Requirements to ESP Systems. 6. Diesel Requirements to PCP Systems.

Figures

1. Typical Configurations Wells – PCP & ESP Systems. 2. Historical Behavior of Oil Production of Rubiales Oil Field. 3. Pareto Diagram – Oil Production of Rubiales Oil Field. 4. BS&W vs Time PCP Wells. 5. BS&W vs Time ESP Wells. 6. BS&W Behavior – RB 31 and RB 45 Wells. 7. Frequency vs BS&W RB-47 Well.