Factors Influencing Mobility Control By Polymer Solutions

1971 ◽  
Vol 23 (03) ◽  
pp. 391-401 ◽  
Author(s):  
R.R. Jennings ◽  
J.H. Rogers ◽  
T.J. West
Keyword(s):  
Polymer Solutions ◽  
Mobility Control ◽  
Factors Influencing

Laboratory Investigations of Factors Influencing Polymer Flood Performance

1975 ◽  
Vol 15 (04) ◽  
pp. 338-346 ◽  
Author(s):  
M.T. Szabo
Keyword(s):  
Oil Recovery ◽  
Polymer Solutions ◽  
Polymer Concentration ◽  
Polymer Flooding ◽  
Mobility Control ◽  
Sweep Efficiency ◽  
Experimental Conditions ◽  
Polymer Injection ◽  
Polymer Flood

Abstract Numerous polymer floods were performed in unconsolidated sand packs using a C14-tagged, cross-linked, partially hydrolyzed ployacrylamide, and the data are compared with brine-flood performance in the same sands. performance in the same sands. The amount of "polymer oil" was linearly proportional to polymer concentration up to a proportional to polymer concentration up to a limiting value. The upper limit of polymer concentration yielding additional polymer oil was considerably higher for a high-permeability sand than for a low-permeability sand. It is shown that a minimum polymer concentration exists, below which no appreciable polymer oil can be produced in high-permeability sands. The effect of polymer slug size on oil recovery is shown for various polymer concentrations, and the results from these tests are used to determine the optimum slug size and polymer concentration for different sands. The effect of salinity was studied by using brine and tap water during polymer floods under similar conditions. Decreased salinity resulted in improved oil recovery at low, polymer concentrations, but it had little effect at higher polymer concentrations. Polymer injection that was started at an advanced stage of brine flood also improved the oil recovery in single-layered sand packs. Experimental data are presented showing the effect of polymer concentration and salinity on polymer-flood performance in stratified reservoir polymer-flood performance in stratified reservoir models. Polymer concentrations in the produced water were measured by analyzing the radioactivity of effluent samples, and the amounts of retained polymer in the stratified models are given for each polymer in the stratified models are given for each experiment. Introduction In the early 1960's, a new technique using dilute polymer solutions to increase oil recovery was polymer solutions to increase oil recovery was introduced in secondary oil-recovery operations. Since then, this new technique has attained wide-spread commercial application. The success and the complexity of this new technology has induced many authors to investigate many aspects of this flooding technique. Laboratory and field studies, along with numerical simulation of polymer flooding, clearly demonstrated that polymer additives increase oil recovery. polymer additives increase oil recovery. Some of the laboratory results have shown that applying polymers in waterflooding reduces the residual oil saturation through an improvement in microscopic sweep efficiency. Other laboratory studies have shown that applying polymer solutions improves the sweep efficiency in polymer solutions improves the sweep efficiency in heterogeneous systems. Numerical simulation of polymer flooding, and a summary of 56 field applications, clearly showed that polymer injection initiated at an early stage of waterflooding is more efficient than when initiated at an advanced stage. Although much useful information has been presented, the experimental conditions were so presented, the experimental conditions were so variable that difficulties arose in correlating the numerical data. So, despite this good data, a systematic laboratory study of the factors influencing the performance of polymer flooding was still lacking in the literature. The purpose of this study was to investigate the effect of polymer concentration, polymer slug size, salinity in the polymer bank, initial water saturation, and permeability on the performance of polymer floods. The role of oil viscosity did not constitute a subject of this investigation. However, some of the data indicated that the applied polymer resulted in added recovery when displacing more viscous oil. The linear polymer-flood tests were coupled with tests in stratified systems, consisting of the same sand materials used in linear flood tests. Thus, it was possible to differentiate between the role of polymer in mobility control behind the flood front in each layer and its role in mobility control in the entire stratified system through improvement in vertical sweep efficiency. A radioactive, C14-tagged hydrolyzed polyacrylamide was used in all oil-recovery tests. polyacrylamide was used in all oil-recovery tests. SPEJ P. 338

Laboratory Study of Polymer Solutions Used for Mobility Control During In Situ NAPL Recovery

1998 ◽  
Vol 18 (3) ◽  
pp. 103-113 ◽  
Author(s):  
K. E. Martel ◽  
R. Martel ◽  
R. Lefebvre ◽  
P. J. Gélinas
Keyword(s):  
Laboratory Study ◽  
Polymer Solutions ◽  
Mobility Control

Mobility Control With Polymer Solutions

1967 ◽  
Vol 7 (02) ◽  
pp. 161-173 ◽  
Author(s):  
W.B. Gogarty
Keyword(s):  
Polymer Solution ◽  
Polymer Solutions ◽  
Control Mechanism ◽  
The United States ◽  
Mobility Control ◽  
High Shear ◽  
Polymer Flow ◽  
Shear Rates ◽  
High Shear Rates ◽  
Secondary Recovery

Abstract With the use of polymer solutions in secondary recovery operations, the need has developed to understand the mobility control mechanism. This study investigated mobility control by considering both permeability and rheological effects. Experiments used a high molecular weight, partially hydrolyzed polyacrylamide polymer. Flow studies took place in reservoir and Berea cores having zero oil saturation. Effective size of the polymer flow unit was inferred from Nuclepore filter tests. Clay studies indicated the particle size capable of decreasing the core permeability. Flushed permeabilities measured the approximate core permeabilities with flowing polymer solutions. These permeabilities were considerably lower than original values. With mobility data and the flushed permeability, maximum effective viscosities were determined for polymer solution flow in a core. Effective viscosities showed that rheological properties play an important part in mobility control with polymer solutions. The study showed that permeabilities decrease and stabilize with polymer flow. At the lower permeabilities, high shear rates exist in the cores. Because of the pseudoplastic character of the polymer solution, the high shear rates caused low effective viscosities. This condition pointed to the inefficient use of the potentially high viscosity of the polymer solution at low shear rates. Introduction In the oil industry, a great deal of interest is being shown in the use of polymer solutions for secondary recovery and a number of polymer floods are being performed in the United States. Some of these floods have become commercial while others have been reported as failures. A number of floods are still in progress and remain to be evaluated. With the advent of polymer flooding, the need developed to understand the mobility control mechanism in porous media.

Shear Degradation of Partially Hydrolyzed Polyacrylamide Solutions

1975 ◽  
Vol 15 (04) ◽  
pp. 311-322 ◽  
Author(s):  
J.M. Maerker
Keyword(s):  
Oil Recovery ◽  
Polymer Solutions ◽  
Significant Loss ◽  
Mobility Control ◽  
Mechanical Degradation ◽  
Elastic Solids ◽  
Shear Degradation ◽  
Flow Through ◽  
Hydrolyzed Polyacrylamide ◽  
Mobility Reduction

Abstract Partially hydrolyzed polyacrylamide solutions are highly shear degradable and may lose much of their effectiveness in reducing water mobility when sheared by flow through porous rock in the vicinity of an injection well. Degradation is investigated by forcing polymer solutions, prepared in brines of various salinities, through consolidated sandstone plugs differing in length and permeability, over a plugs differing in length and permeability, over a wide range of flow rates. A correlation for degradation based on a theoretical viscoelastic fluid model is developed that extends predictive capability to situations not easily reproduced in the laboratory. Mobility-reduction losses in field cores at reservoir flow rates are measured following degradation and are found to depend strongly on formation permeability. Consideration of field applications shows that injection into typical wellbore geometries can lead to more than an 80-percent loss of the mobility reduction provided by undegraded solutions. Also discussed are consequences for incremental oil recovery and the possibility of injecting through propped fractures. possibility of injecting through propped fractures Introduction Susceptibility of commercially available, partially hydrolyzed polyacrylamides to mechanical, or shear, degradation represents a serious problem regarding their applicability as mobility-control fluids for secondary and tertiary oil recovery applications. The approach taken in this work assumes that surface handling equipment in the field (pumps, flow controllers, etc.) have been adequately designed to minimize effects of shear degradation in all operations preceding actual delivery of the polymer solution to the sand face. The remaining problem is to assess the mechanical degradation a polymer solution experiences when it enters the porous matrix at the high fluxes prevailing around injection wells. Ability to predict the degree of mobility-control loss based on a laboratory investigation of the relevant parameters is desirable. White et al. were the first to attempt prediction of matrix-induced degradation, but the result was only a recommended injection-rate limit for minimizing polymer degradation for two specific wellbore completions. More recent papers offer limited data supporting the contention that matrix-induced degradation of polyacrylamide solutions results in significant loss polyacrylamide solutions results in significant loss of mobility control . This paper investigates the cause of mechanical degradation in dilute polymer solutions and presents experimental data on the effects of polymer concentration, water salinity, permeability, flow rate, and flow distance. permeability, flow rate, and flow distance. Several interesting and unexpected conclusions are drawn from the results. BACKGROUND - THEORETICAL CONCEPT The mechanical degradation of polymer solutions occurs when fluid stresses developed during deformation, or flow, become large enough to break the polymer molecular chains. Historically, the feeling has been that shearing stresses in laminar shear flow or turbulent pipe flow were responsible for chain scission. However, recent data reported by Culter et al. suggest that degradation of viscoelastic polymer solutions in capillary tubes may be dominated by large elongational or normal caresses occurring at the entrance to the squared-off capillaries. Such stresses result from Lagrangian unsteady flow, or elongational deformation, at the tube entrance. Flow through porous media also generates velocity fields that are sufficiently unsteady, in the Lagrangian sense, to lead one to anticipate large viscoelastic normal stresses. Viscoelastic fluids are materials that behave like viscous liquids at low rates of deformation and partially like elastic solids at high rates of partially like elastic solids at high rates of deformation. Several constitutive models are available for describing the stress-strain behavior of such fluids. SPEJ P. 311

Shear Viscosities of Ionic Polyacrylamide Solutions

1972 ◽  
Vol 12 (06) ◽  
pp. 469-473 ◽  
Author(s):  
Necmettin Mungan
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Shear Rate ◽  
Polymer Solution ◽  
Polymer Solutions ◽  
Mobility Control ◽  
Permeability Reduction ◽  
Experimental Conditions ◽  
Molecular Weights ◽  
Stock Solutions

Abstract Solutions of ionic polyacrylamide polymers behave pseudoplastic in purely viscometric flow. Flow rate, polymer molecular weight and electrolytes affect solution viscosities to a large extent. Equations are given for the viscosity-shear rate relations in a form that can be used conveniently to account for the effect of viscosity on mobility. Introduction Polymers are being used increasingly in oil recovery operations, and therefore, an understanding of their flow behavior is gaining pragmatic importance. Past studies have shown that in the flow of polymeric fluids through porous media, the increase in solution viscosity, decrease in permeability, and viscoelastic deformations cause permeability, and viscoelastic deformations cause the fluid mobility to be greatly reduced. In general, viscoelasticity, i.e., extensional flow, is not so important because, for the largest part of a reservoir, polymer solution moves at very low and fairly steady polymer solution moves at very low and fairly steady velocities. Jennings et al. have concluded this for the specific polymers that they studied. Permeability reduction plays an important role in Permeability reduction plays an important role in the mobility control, particularly in porous media having low permeabilities initially. Reductions ranging from 25 to 70 times have been reported. However, the alterations that take place in a porous medium during polymer flow, the coupling between the geometry of the porous medium and the properties of the flowing fluid, and the influence of the flow regime on permeability have not been looked into in sufficient detail. A separate study, directed to the understanding of these important phenomena is required. In the present work, the purely viscous behavior of solutions of three partially hydrolized polyacrylamide polymers was obtained under experimental conditions far polymers was obtained under experimental conditions far more extensive than any reported in the literature. Some data have been available in the past for two of the polymers, but the third is a new polymer for which no data have been reported before. Using a Weissenberg rheogoniometer, Cannon-Fenske viscometers, and various capillary cubes, viscosities were measured over 8 decades of shear rate, ranging from 10 to to 10 (5) sec-1. These are the limits of measurable rates of shear and cover those that may apply to flow in reservoirs. Distilled water and various NaCl solutions were used as solvents to afford comparison of the rheological properties between fresh and saline solutions. Measurements were also made with solutions containing calcium' and magnesium to study the effect of divalent cations. EXPERIMENTAL The three polymers, Nos. 500, 700 and NC 1870, are partially hydrolized polyacrylamides manufactured by The Dow Chemical Co., and were from lots 8085, 52 and 87-8100E, respectively. Polymer NC 1870 is currently at a developmental stage and can be obtained in limited quantities; the other two have been available commercially for some time, have been used in the laboratory and in the field. All three are hydrolized to the same extent, containing approximately 25 percent polyacrylate, with the remainder being polyacrylamide. The molecular weights of Nos. 500 and 700 are 2 to 3 and 3 to 7 million, respectively. That of the NC 1870 is higher, but has not been measured due to the usual difficulties in measuring such high molecular weights. Polymer and salt concentrations are given on a weight-parts per million basis. Reagent grade chemicals and double-distilled deaerated water, having a pH of 6.5, were used in all solutions. Formaldehyde was added as a bactericide. To the extent possible, air was kept out of the solutions to avoid oxidation-type degradation of the polymers. Polymer solutions were mixed using magnetic Polymer solutions were mixed using magnetic stirrers and carefully avoiding any mechanical degradation. Solutions of desired concentrations were prepared from stock solutions by dilution. The latter had been passed through 1-micron millipore filters, were optically clear, containing no fish-eyes. The polymer concentration of stock solutions was determined by turbidimetry and nitrogen analysis, the two methods usually agreeing within a few percent. percent. SPEJ P. 469

Study on Properties of Pectinate Hydrophobically Associating Polyacrylamide Solutions

2011 ◽  
Vol 361-363 ◽  
pp. 526-529 ◽  
Author(s):  
Lei Ting Shi ◽  
Xiao Nan Li ◽  
Wei Zhou ◽  
Song Xia Wang ◽  
Qiong Yang ◽  
...  
Keyword(s):  
Polymer Solutions ◽  
Flow Characteristics ◽  
Viscosity Measurement ◽  
Mobility Control ◽  
High Permeability ◽  
Core Flow ◽  
Hydrophobically Associating Polyacrylamide ◽  
Hydrophobically Associating ◽  
Flow Experiments ◽  
Associating Polymer

In this article, the viscosifying abilities, rheological properties, flow characteristics of pectinate hydrophobically associating polymer (PHAP) solutions with different hydrophobe content were studied using technical methods of viscosity measurement, rheological and core flow experiments. Researches on viscosifying of different PHAPs at 20°C and 65°C in distilled water and saline indicate that, with the raise of hydrophobe content, viscosity of polymer solutions increases first and then decreases, which means that there should be a critical hydrophobe content( CHC). Below CHC, the anti-shear ability of polymer solutions enhances as hydrophobe content rises; while the shear resistance would fall down when and after the content reaches CHC. In high permeability porous media, all polymer solutions take on greater injectivity, and RFF can all be higher than 5, yet with the increasing of hydrophobe content, RF goes up first and then declines. It could be an effective way to enhance mobility control ability, improve polymer flooding effect in high permeability reservoirs and design polymer molecular structure more reasonably, using the pectinate structure and hydrophobic association interaction between polymer moleculars.

Factors influencing adhesive bonding at the bone/implant interface

1992 ◽  
Vol 50 (2) ◽  
pp. 1114-1115
Author(s):  
Julie A. Martini ◽  
Robert H. Doremus
Keyword(s):  
Electron Microscopy ◽  
Adhesive Bonding ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Bone Implant ◽  
Factors Influencing ◽  
Lr White ◽  
Transmission Electron ◽  
New Zealand White Rabbits ◽  
Scanning Electron

Tracy and Doremus have demonstrated chemical bonding between bone and hydroxylapatite with transmission electron microscopy. Now researchers ponder how to improve upon this bond in turn improving the life expectancy and biocompatibility of implantable orthopedic devices.This report focuses on a study of the- chemical influences on the interfacial integrity and strength. Pure hydroxylapatite (HAP), magnesium doped HAP, strontium doped HAP, bioglass and medical grade titanium cylinders were implanted into the tibial cortices of New Zealand white rabbits. After 12 weeks, the implants were retrieved for a scanning electron microscopy study coupled with energy dispersive spectroscopy.Following sacrifice and careful retrieval, the samples were dehydrated through a graduated series starting with 50% ethanol and continuing through 60, 70, 80, 90, 95, and 100% ethanol over a period of two days. The samples were embedded in LR White. Again a graduated series was used with solutions of 50, 75 and 100% LR White diluted in ethanol.

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