Progressive Cavity Pump Research Articles

Leakage flow correlation of a progressive cavity pump delivering shear thinning non-Newtonian fluids

The majority of the complex fluids in petroleum engineering applications are shear thinning non-Newtonian. The industry pumps non-Newtonian fluids by progressive cavity pumps (PCPs) are being used for pumping non-Newtonian fluids in the petroleum industry from the past few years. In this work, an experimental setup was developed and the objective is to study the performance of a PCP delivering shear thinning non-Newtonian fluids and the effect of speed, slurry viscosity and differential pressure on the leakage and volumetric efficiency of the pump. The fluids were prepared by mixing bentonite, water and 0.06% of Na2CO3 to maintain pH level at 8.5-9.5, and the mixture produced are shear thinning non-Newtonian fluid. It was observed that the pump efficiency increases with the increase in viscosity, which reduces the pump leakage. At a higher speed, the pump leakage was lower and volumetric efficiency was higher while increased differential pressure caused an increase in leakage and a decrease in volumetric efficiency. Using the experimental results, a polynomial regression model was developed to predict the leakage of the pump. The correlation development approach can be implemented in the other type of pumps and can cut down experimental expenses. [Received: May 24, 2015; Accepted: January 9, 2016]

Leakage flow correlation of a progressive cavity pump delivering shear thinning non-Newtonian fluids

The majority of the complex fluids in petroleum engineering applications are shear thinning non-Newtonian. The industry pumps non-Newtonian fluids by progressive cavity pumps (PCPs) are being used for pumping non-Newtonian fluids in the petroleum industry from the past few years. In this work, an experimental setup was developed and the objective is to study the performance of a PCP delivering shear thinning non-Newtonian fluids and the effect of speed, slurry viscosity and differential pressure on the leakage and volumetric efficiency of the pump. The fluids were prepared by mixing bentonite, water and 0.06% of Na2CO3 to maintain pH level at 8.5-9.5, and the mixture produced are shear thinning non-Newtonian fluid. It was observed that the pump efficiency increases with the increase in viscosity, which reduces the pump leakage. At a higher speed, the pump leakage was lower and volumetric efficiency was higher while increased differential pressure caused an increase in leakage and a decrease in volumetric efficiency. Using the experimental results, a polynomial regression model was developed to predict the leakage of the pump. The correlation development approach can be implemented in the other type of pumps and can cut down experimental expenses. [Received: May 24, 2015; Accepted: January 9, 2016]

Biaxial Mooney-Rivlin Coefficient of Silicone Sheet by Additive Manufacturing

This study evaluates the biaxial Mooney-Rivlin coefficient for silicone sheets made by additive manufacturing (AM) for custom wearable assistive devices and soft robotics. The extrusion-based layer-by-layer technique is applied for AM of moisture cured silicone sheets. A progressive cavity pump controls the precise, continuous flow of high viscosity silicone for low void AM of the cruciform shaped specimen. A biaxial tensile test apparatus with four independent linear actuators was built for testing the cruciform specimens. Digital Image Correlation method was utilized to calculate the distribution of strain. This study show the value of the biaxial Mooney-Rivlin coefficient for the AM silicone sheet is independent of the thickness and in the range of 114.7kPa to 132.1kPa for C10 and –17.9kPa to –9.04kPa for C01. The geometry of the specimen is shown to affect the biaxial quality of the specimen.

Simulation of single-phase liquid flow in Progressing Cavity Pump

Progressing Cavity Pump (PCP), also known as Moineau pump, is an artificial lift method often used for pumping high viscosity and high solids content fluids from producing wells. Although, PCP has been effectively adopted in oil industry for decades, there is a lack of understanding the effect of its design parameters and operating conditions on the pump performance. The objectives of this study are to develop a model for predicting an actual multi-lobe PCP performance, and to investigate pump performance through simulating single-phase liquid flow behavior. The proposed model is a combination of two existing models in the literature, namely an analytical model to predict the theoretical pump performance, and a slippage model. The proposed model can be used not only to predict the actual multi-lobe PCP performance, but also to optimize pump design under given operating conditions. To validate the modeling results, an experimental study was carried out using a commercial PCP. The experiments were conducted with liquid viscosities ranging from 0 to 450cp, rotational speeds ranging from 0 to 300RPM, and pump differential pressures ranging from 0 to 300psi. The validation study revealed satisfactory results and reasonable match between the model predictions and experimental results. Using the developed model, an extensive sensitivity analysis was performed, which suggested that higher viscosity, in most of cases, minimizes pump slippage. In addition, if the pump clearance is smaller than a specific value, then the effects of differential pressure and liquid viscosity on the pump performance are minimal. Similarly, if the pump clearance is less than a specific value, then a pump with higher stator lobe number will deliver higher actual pump rate. The results of this study are not only important for manufacturers to optimize PCP design, but also for operators to improve PCP operational pump performance and pump efficiency.

The Effect of Carbon Dioxide Pressure in Carbon Steel Corrosion in 5 Wt.% NaCl Solution Using Flow Loop

The pipelines transport a raw, unrefined well stream, usually consisting of a multiphase flow of gas, oil and water contained carbon dioxide, hydrogen sulfide and chlorides at elevated temperatures. Internal corrosion is the important factor affecting the reliability and longevity of subsea oil and gas pipelines in the oil and gas field. In the pipeline design, the measurement of corrosion rate was evaluated under similar corrosion environments using flow loop. The flow loop installed at KITECH located in Korea was made of UNS 31603 with internal diameter 1 inch and corrosion tests can be performed up to 7 m/s liquid velocity and up to 12 m/s gas velocity under maximum pressure 10 MPa. The flow loop system was comprises of a progressive cavity pump, separator, corrosion test section and corrosion monitoring equipment such as electrical resistance probes, linear polarization resistance probes. Corrosion inhibitor performance test, gas hydrate test etc. can be conducted with the system. Material of the coupon was API 5L X52 and weight loss coupon method was adopted based on NACE Standard RP 0775-2005. Measurement of corrosion rate was conducted under test conditions, 0 and 0.5 MPa, dissolved oxygen concentration less than 10 ppb, temperature 313 K, for 24 hours in NaCl 5wt. % solution at the velocity of 3 and 4 m/s respectively. The test results showed that corrosion rate increased at higher flow rate and the predominant factor of corrosion was not chloride concentration but pH of the internal liquid of the flow loop.

The effects of temperature on the mechanical and tribological properties of progressing cavity pump NBR stator rubber

This study used immersion and wear experiments to examine the swelling and tribological behaviors of nitrile-butadience (NBR) rubber with three acrylonitrile contents (N18, N26, and N41) in crude oil at varying temperatures. The results showed that in a crude oil medium with increasing temperatures, the N18 volume change rate (VCR) increased linearly, the N41 VCR decreased slightly, and N26 experienced a smaller change. As the temperature rose, the tensile strength and tensile fracture permanent deformation of NBR reduced. As the soaking temperature rose, the NBR wear loss increased and the friction coefficient decreased. When the rubber was soaked in crude oil, swelling gradually spread from the external portion to the internal portion. Due to its compact structure, NBR with high acrylonitrile content exhibited good heat resistance, swelling resistance, mechanical properties, and wearing capacity, but a poor resilience.DOI: http://dx.doi.org/10.5755/j01.mech.22.4.16162

A 3D Transient Model for the Multiphase Flow in a Progressing-Cavity Pump

Summary This paper presents the development of a computational-fluid-dynamics (CFD) model for the 3D transient two-phase flow within a progressing-cavity pump (PCP). The model implementation was only possible because of the meticulous mesh-generation and mesh-motion algorithm, previously published by the authors, which is briefly described herein. In this algorithm, a structured mesh was generated by defining all nodes’ positions and connectivities, for each rotor position by means of FORTRAN subroutines, which were embodied into ANSYS CFX software. The model is capable of predicting accurately the volumetric efficiency and the viscous losses, and it provides detailed information of pressure and velocity fields and void distribution along the pump. Such information could be of fundamental importance for product development and/or optimization for field operation. In field applications, the common situation is that in which the oil comes into the pump accompanied with free gas, which characterizes a multiphase flow. Simplified models on the basis of the calculation of the backflow or “slippage,” which is subtracted from the displaced flow rate, fail to characterize the PCP performance under multiphase conditions because the slip is variable along the pump. In this model, the governing equations were solved with an element-based finite-volume method in a moving mesh. The Eulerian-Eulerian approach, considering the homogeneous model, is used to model the flow of the gas/liquid mixture. The compressibility of the gas is taken into account, which is one of the main shortcomings in positive/constant displacement pumps. The effects of the different gas-volume fractions (GVFs) in pump volumetric efficiency, pressure distribution, power, slippage flow rate, and volumetric flow rate were analyzed, and some new insights are presented about the slippage in PCPs operating in multiphase conditions. The results show that the developed model is capable of reproducing pump dynamic behavior under multiphase-flow conditions performed early in experimental works.

Run-Life Improvement by Implementation of Artificial-Lift-Systems Failure Classification

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 173913, “Run-Life Improvement by Implementation of Artificial-Lift- Systems Failure Classification and Root-Cause Failure Classification,” by Edward Rubiano, José Luis Martin, Jesus Prada, Manuel Monroy, Laura Labrador, Jonathan Celis, and Jahir Gutierrez, Oxy, and Michel Bohorquez, Ecopetrol, prepared for the 2015 SPE Artificial Lift Conference—Latin America and Caribbean, Salvador, Brazil, 27–28 May. The paper has not been peer reviewed. This paper describes a methodology for classification of artificial-lift-system (ALS) failures and addition of a commonly used root-cause failure classification. This methodology was applied to different ALSs such as beam pumps (BPs), progressing cavity pumps (PCPs), electrical submersible pumps (ESPs), and electrical submersible progressing cavity pumps (ESPCPs). The starting point was the definition of the boundaries of each system. Then, each job in the well was defined as (1) a failure, (2) a failure, non-ALS, or (3) no failure, in order to look for ways to improve run life. Introduction La Cira-Infantas oil field is in the Middle Magdalena Valley in Colombia (Fig. 1). The vast majority of the wells are completed with 7-in. production casing and perforated with 5 shots/ft with no sand-control completion in place, and then the ALS is installed. ALS in La Cira-Infantas From the beginning of the activity in La Cira-Infantas, almost 100 years ago, several ALSs have been used to produce fluids from the wells. Since 2005, the field has offered different conditions, depending on the mature state of the waterflooding— high water percentage, high and low flow rates, free gas, and corrosive fluids. Currently, ALSs such as BPs, PCPs, ESPs, and ESPCPs are used for producing the total fluid of the field. Failure Analysis The root-cause failure-analysis (RCFA) process used in La Cira-Infantas has the objective of finding the real cause of a given failure and identifying effective solutions to prevent a recurrence of the failure. The steps for the RCFA are as follows. Initial Diagnosis and Failure Confirmation. When an ALS ceases to lift the expected production, specific procedures are performed to try to restart the system. If production is not re-established, a downhole failure is confirmed. Pulling Equipment From the Well. Mechanical and electrical tests are performed to determine ALS condition. Tubing is tested for leaks. As equipment is pulled, each part of the ALS is inspected carefully and qualitative measurements are taken.

Role of Electrical Submerged Pumps in Enabling Asphaltene-Stabilized Emulsions

Many oilfield development projects require artificial lift systems, i.e., methods to enhance well fluid production that are needed when the reservoir pressure is too low to allow for the produced fluid to reach the surface. Such an approach is of particular interest for mature oilfields (such as those in the Middle East and North Africa) and for many of the upcoming deepwater and ultra-deepwater fields under development around the world. Artificial lifting can be achieved by gas lifting or through a pump installed into the well. For subsea downhole applications, a progressive cavity pump (PCP) or (centrifugal) electrical submersible pump (ESP) is employed. ESP systems are having, in particular, wide spreading, essentially as a result of the good efficiencies and high rates and depth. In search of means for maximizing the productivity of each well that sometimes leads to looking for producing the maximum in the shortest possible time, these pumps are seen as a sort of panacea. In this work, a dangerous pos...

BioPrint: A Liquid Deposition Printing System for Natural Actuators

Abstract This article presents a digital fabrication platform for depositing solution-based natural stimuli-responsive material on a thin flat substrate to create hygromorphic biohybrid films. Bacillus subtilis bacterial spores are deposited in the printing process. The hardware system consists of a progressive cavity pump fluidic dispenser, a numerical control gantry, a cooling fan, a heating bed, an agitation module, and a camera module. The software pipeline includes the design of print patterns, simulation of resulting material transformations, and communication with computer hardware. The hardware and software systems are highly modularized and can therefore be easily reconfigured by the user.

METHODOLOGY FOR CALCULATING SUCKER ROD STRING OF PROGRESSING CAVITY PUMP

The article consider a methodology for calculation the sucker rod string of progressing cavity pump. Method of calculation involves determining the axial, torsion and bending loads acting on the rod string during their rotation, as well as their rise during tripping operations. Method of calculation is given only for three-interval wells including vertical and inclined sections of the wellbore, as well as the section of the wellbore with the local curvature. The article describes the method of calculation of the stress in the metal sucker rod with the experimentally obtained dependence of the joint impact of the oil viscosity, the relative velocity of the rubbing bodies and specific normal load, as a result, of research of friction pairs of elements sucker rod for progressing cavity pump. The article consider the friction coefficients depending on the number of Sommerfeld for pairs of friction (coupling on tube, rods on tube, rod on centralizers and the pump rotor on the stator). The proposed method allows designing rod string with the boundary and hydrodynamic friction, and predicting their optimal parameters at the design stage. An integrated approach to the calculation will allow developing appropriate technical solutions for further improving the design elements of the rod string, in order to reduce loads and power consumption of the installation.

Numerical investigation of contact stress between rotor and stator in a two-lead progressing cavity pump

Abstract The contact stress between rotor and stator in a progressing cavity pump (PCP) is critical to seal performance and service lifetime of the PCP. In this paper, an approach to predict the contact stress and friction behavior in PCPs is proposed. The approach is based on the results from the finite element analysis (FEA) and Stribeck-type curve. A three-dimensional finite element model for the contact stress between the rotor and the stator within a two-lead PCP is successfully established. The fluid pressure, the eccentric force and the laden torque are applied to the model. And the finite element analysis is conducted to investigate the contact stress between the rotor and the stator in the two-lead PCP. The simulated results show that the contact stress in the spiral seal lines (SPSLs) is always high compared to that in warping seal lines (WSLs) at the identical relative position, and the contact stress increases along seals from the first seal line to the last one. The maximum contact stress of the PCP appearing in every seal line is off-center. It is found that the serious wear and/or damage for the progressing cavity pump during operating always occurs on the paths which are off-center of the spiral seal lines. The results are validated against the actual phenomenon which appeared in oilfields from open literatures.

Reliability Improvement in Beam Pumps by Use of a Unique Methodology

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 171372, “Reliability Improvement in Beam Pumps by Use of a Unique Methodology Combining Real-Time Automation and Failure Analysis,” by Blair Gardner, SPE, Santos, prepared for the 2014 SPE Artificial Lift Conference and Exhibition—North America, Houston, 6–8 October. The paper has not been peer reviewed. This paper focuses on analysis of beam-pump-failure root causes and trends and how the operator has used these data combined with automated equipment to reduce failure frequency and operating cost. The paper also presents data and findings to support the benefits of a beam-pump-automation and -control program. Introduction The operating company has operated a fleet of beam pumps in the Cooper basin in central Australia since 1985. The basin extends over 30 000 km2 in a remote, harsh, arid desert. Ambient air temperature can range from 0°C to greater than 50°C, and there is potential for flood events in the wet season. The remote location and variety of weather conditions present numerous operational challenges and technical constraints. Historically, the beam pumps have run in a traditional manual mode whereby production operators measure, record, and analyze operating parameters and monitor surface-equipment condition. The operator implemented an automation program in 2006 to help improve run life; increase production; and decrease environmental, health, and safety risk. Artificial-Lift Selection The operator installs and operates many mainstream artificial-lift systems (ALSs) including electric submersible pumps (ESPs), progressing-cavity pumps (PCPs), jet pumps, and beam pumps. Artificial lift is installed on every oil well, with selection criteria being based on the expected fluid rate in conjunction with any surface- facility constraints. The operator installed its first beam pump in 1985; these have been the dominant ALS for yielding fluid rates from 20 to 1,000 BFPD, a range into which most oil wells fall. In 2005, a decision was made to switch to PCPs as the preferred ALS for new wells; this decision was reversed back to beam pumps in 2008 following poor PCP reliability. Past Operating Strategy Failure Diagnosis and Analysis. In the past, following discovery of a suspected downhole failure, the operator would run a standard suite of diagnostics, which included collecting a manual dynacard and running a pump-up pressure test, before placing the well “on tap” (or tagging bottom) in an attempt at reinstating production. If this was unsuccessful, the well was transferred to the production engineer to justify and scope a downhole-repair workover. No formal record of diagnosis or activities attempted to reinstate pumping action was preserved. Once a pump repair was executed, the rig reports were filed in the field-office well file. Consequently, information regarding the root cause of failure was often inconsistent in reporting standard, and it was not recorded and collated systematically in any central repository to enable future analysis. Cooper Basin and the Digital Oil Field—Beam-Pump Automation and Telemetry Implementation. In 2006, none of the operator’s Cooper basin beam-pump fleet had any form of automation or telemetry. One of the outcomes of the unsuccessful PCP program was a better understanding of the benefit that control and telemetry have on artificial-lift performance and reliability. When the switch was made back to beam pumps as the preferred ALS, it was evident that some level of automation would be required. The operator retrofitted two platforms of control to its beam-pump fleet. The selection criteria were based predominantly on individual-well economics, rather than a generic approach. Variable-Speed Drive (VSD) (Advanced). A VSD is used to automatically adjust an electric motor and, consequently, pump speed to match well inflow; target pump fill is used as a feedback loop to the VSD control algorithm. Benefits include maximized production by self-optimization, advanced condition monitoring, and equipment protection. This is the preferred system for all new beam-pump installations. Pumpoff Control (POC) (Basic). A rod-pump controller (RPC) was retrofitted to existing engine-driven beam pumps that could not justify the cost of VSD installation. The system has no ability to self-optimize; however, the RPC shuts the pump down if a severely pumped-off condition is reached or if rod-load limits are exceeded. Benefits include basic condition monitoring and equipment protection.

Reducing Tubing Failures in the Tambaredjo Field, Suriname

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 169978, “Case Study for Reducing Tubing Failures in Suriname’s Tambaredjo Field,” by D. Nurmohamed, SPE, H. Chin A Lien, SPE, and S. Kisoensingh, SPE, Staatsolie Maatschappij Suriname, prepared for the 2014 SPE Trinidad and Tobago Energy Resources Conference, Port of Spain, Trinidad and Tobago, 9–11 June. The paper has not been peer reviewed. In the 30 years of operations on Suriname’s Tambaredjo field, the prime mechanism for lifting the 15.6 °API crude to surface has been that of progressing cavity pumps (PCPs). In the period from 2008 to 2012, an annual average of 580 downhole failures occurred, 54% of which were caused by tubing leaks. In an effort to reduce these tubing failures, a pilot program was commenced to install rod guides in wells with the highest failure rate and to install a 25-ft sucker rod directly above the pump. Introduction Currently, Staatsolie Maatschappij Suriname produces from the Tambaredjo, Calcutta, and Tambaredjo Northwest fields, as illustrated in Fig. 1. These oil fields are located in a marshy area on the coastal plain of Suriname approximately 55 km west of Paramaribo. The crude oil contains low sulfur content (0.65 wt%) and 1 wt% asphaltene and has an average viscosity of 500 cp at reservoir conditions. The water/oil ratio is 7 and the gas/oil ratio is less than 50 scf/bbl as of December 2013. The average daily production from these fields reached 16,700 BOPD from 1,549 active producing wells completed in shallow unconsolidated-sand reservoirs with depths ranging from 700 to 1,500 ft. The Tambaredjo oil field is the oldest and largest of these fields, with 1,130 active producers contributing two-thirds of the overall production. Mechanical Wear of Tubing The majority of tubing failures in the Tambaredjo field are repetitive in nature. Mechanical wear is the removal of metal caused by the frictional rubbing of the sucker-rod string against the inner wall of the tubing. This frictional rubbing can be increased by the movement of the rod string, often characterized as stick/slip.

Development of a new hollow sucker rod family for rotating pumping (progressive cavity pump systems)

Abstract Conventional solid sucker rods according to API 11B specification are widely used for rotating pumping, particularly to drive PCP Systems (progressive cavity pump systems) during the oil production. However, these products have been developed to work under axial alternating loads, and not under torsional loads. Thus, the use of these rods for rotating pumping has several limitations and disadvantages like a low yielding torque, insufficient backspin and fatigue resistance, showing low performance and resulting in high operative costs for artificial lift systems. Furthermore, the PCP System requires higher torque to work efficiently. For that reason, it is suitable to develop a new product with better performance to be used for this pumping system. This paper presents the development of a family of innovative products called “Hollow Sucker Rod” as a technical solution for PCP System. The development consisted of (i) design of the connection, (ii) manufacture of prototypes, (iii) full scale lab tests, and (iv) field trials. Some advantages of this new technology are: (i) high torque load to yielding, (ii) good fatigue resistance, (iii) high backspin resistance, (iv) less tubing wear, (v) increase in pumping rates, (vi) possibility to inject different kind of fluids by the inside of the “Hollow Sucker Rod”, and (vii) easy to make up and install (conventional pulling ring).

Learning from lessons in downhole gauges as part of a well optimisation strategy

Downhole gauges are designed to operate in a harsh working environment and are commonly installed in conjunction with a progressing cavity (PC) pump. They measure the pressure at or slightly above the PC pump and, along with a casing pressure gauge, they can be used to measure the fluid level in the well. An understanding of the fluid level in a well allows the operator to control the well drawdown process and protect the PC pump if it is installed with a well optimisation system that can maintain the desired water level or stop the pump if required. Downhole gauges provide valuable data for reservoir analysis and well planning, especially for low-perm coals. They are often criticised for failing, but root cause analysis often finds that failure is not the gauge, rather it is caused by other components of the well completion. This extended abstract discusses the operational experience and analysis of operating downhole gauges across a 10-year period while working with several gas companies in Queensland, NSW and China. In these locations different cable-type downhole gauges, such as a low-density polyethylene (LPDE) sheathed, armoured cables and solid tubular stainless steel cables, were fixed to the tubing. This knowledge can extend the working life of downhole gauges and help operators develop well optimisation strategies.

Finite element analysis for adhesive failure of progressive cavity pump with stator of even thickness

Abstract Compared to conventional progressive cavity pump (PCP), even thickness PCP has numerous advantages such as uniform thermal and swelling expansion, stable operation and high volumetric efficiency. However, adhesive failure occurs on the stator of even thickness PCP more often in actual working conditions, which limits its development and application. In this study, finite element models of conventional PCP and even thickness PCP with the same structural parameters are established and simulated to find the mechanism for adhesive failure. We primarily study the force conditions of adhesive interface which bonds the stator and cylinder sleeve. The results show that shear strain caused by hydraulic pressure difference and interference displacement is quite large around the adhesive interface of even thickness PCP. The too large shear strain around the adhesive interface is the main cause of adhesive failure. Based on this analysis, the relationship between the shear strain and design parameters, such as the rubber adhesion ratio, pressure difference, elastic modulus of stator, magnitude of interference and wall thickness, is investigated. Our results show that the shear strain increases greatly and adhesive failure tends to occur in certain conditions. Furthermore, two new techniques to enhance the adhesive performance are presented and validated with our finite element analysis. Our research can be of great significance for guiding the design and optimization of even thickness PCPs.

Polymer-Flooding-Pilot Learning Curve: Five-Plus Years' Experience To Reduce Cost per Incremental Barrel of Oil

Summary This paper deals with the learning curve of a five-plus-year polymer-flooding pilot conducted in a mature waterflood that includes, for example, several works related to injector and producer wells and reservoir management. The scope of this paper is to describe the learning curve during the last 5 years rather than the reservoir response of the polymer-flooding technique; focus is on the aspects related to reduce cost per incremental barrel of oil for a possible extension to other waterflooded areas of the field. Diadema oil field is in the San Jorge Gulf basin in the southern portion of Argentina. The field is operated by CAPSA, an Argentinean oil-producer company; it has 480 producer and 270 injector wells (interwell spacing is 250 m on average). The company has developed waterflooding over more than 18 years (today, this technique represents 82% of oil production in the field) and produces approximately 1600 m3/d of oil and 40 000 m3/d of gross production (96% water cut) with 38 400 m3/d of water injection. The reservoir that is polymer-flooded is characterized by high permeability (average of 500 md), high heterogeneity (10 to 5,000 md), high porosity (30%), very stratified sandstone layers (4 to 12 m of net thickness) with poor lateral continuity (fluvial origin), and 20 °API oil (100 cp at reservoir conditions). Diadema's polymer-flooding pilot started in October 2007 on five water injectors (it includes 13 injectors today) with an injected rate of 1000 m3/d (today, 2000 m3/d). Polymer solution is made with produced water (15,000 ppm brine) and 1,500 ppm of hydrolyzed polyacrylamide polymer reaching 15- to 20-cp fluid-injection viscosity. Oil-production rate from the original “central” producers (wells that are aided with 100% of polymer injection) has increased 100% at the same time as average reduction in water cut is approximately 15%. The main aspects presented in this work are depth profile modification with crosslinked gel injected along with polymer, use of “curlers” to regulate injection in multiple wells with one injection pump without shearing the polymer, and an improved technology on producer wells with progressing-cavity pumps to decrease shut-in time and number of pump failures. The plan for the future is to extend this project to other areas with the acquired knowledge and to improve different aspects, such as water quality and optimization of polymer plant operation. These improvements will allow the company to reduce operating costs per incremental barrel of oil.

Progressive Cavity Pump: A Review

Progressive Cavity Pump: A Review

Leakage Analysis of Metal Progressive Cavity Pump

A Progressive cavity pump is an artificial lifting technique used in oil and gas industries to pump heavy and sandy fluids from the low bottom hole pressure wells. The pump is a positive displacement pump having rotor and stator as the main component of the pump. The performance of pump gets decreased as the clearance between the rotor and stator increases. Increasing fluid viscosity has positive effect on the performance. The performance degradation of the pumpoccurs due to leakage flow through the least clearance gap between the rotor and stator. A computational work has been performed to find the characteristics of the leakage flow and Ansys CFX 12.1 software was used for the simulations. Meshing and solving of the fluid dynamics equation were done by Ansys CFX mesh and CFX solver, respectively. Present article presents the prediction of leakage for different fluid viscosities and diametric clearances.It was found that the rotor rotation helps in leakage flow if the flow and rotor surface velocity directions are same.