A Potentiometric Study of the Effects of Mobility Ratio on Reservoir Flow Patterns

1961 ◽  
Vol 1 (03) ◽  
pp. 125-129 ◽  
Author(s):  
H.B. Bradley ◽  
J.P. Heller ◽  
A.S. Odeh
Keyword(s):  
Mobility Ratio ◽  
Prototype System ◽  
Sweep Efficiency ◽  
X Ray ◽  
Reservoir Flow ◽  
Well Pattern ◽  
Before And After ◽  
Production Wells ◽  
Production History ◽  
Water Cut

Abstract A potentiometric model technique is presented for determining the a real sweep efficiency of a five-spot well pattern, at and beyond breakthrough. A sharp interface between displaced and displacing fluids is assumed. Although the prototype system is referred to as a water flood operation, obvious changes in the notation and computations will adapt the results to other displacement processes. The results of the study include the following.Areal sweep efficiencies for a five-spot well pattern, at and beyond breakthrough, for mobility ratios (displacing to displaced fluid) of 4:1, 2:1, 1:1 and 1:4.Extension of potentiometric analysis to the investigation of the areal sweep-efficiency beyond breakthrough in a five-spot pattern by the application of conformal mapping and conductive-solid models.The use of layers of conductive fabric in representing mobility ratio changes in potentiometric models.The development of a probe mechanism for probing conductive solids. The results obtained by conductive-cloth models agree with earlier areal sweep efficiencies at breakthrough obtained by Aronofsky and Ramey on the potentiometric analyzer using electrolytic-tank models. Results beyond breakthrough differ from those obtained by the X-Ray Shadowgraph technique. Data from this study show that, for mobility ratios greater than one, water cut rises rapidly as fluid is produced after breakthrough. However, for mobility ratios smaller than one, a large increase in area swept resulted with only a small increase in water cut. Introduction In calculating reservoir performance of waterflooding operations and other fluid-injection programs, it is necessary to estimate the areal sweep efficiency before and after injected-fluid breakthrough into production wells. Influence of mobility ratio on oil-production history, before and after breakthrough for a five-spot well pattern, has been studied by X-Ray Shadowgraph techniques and by gelatin models. In none of these investigations was the transition zone controlled experimentally.

Successful Field Pilot of In-Depth Colloidal Dispersion Gel (CDG) Technology in Daqing Oilfield

2006 ◽  
Vol 9 (06) ◽  
pp. 664-673 ◽  
Author(s):  
Harry L. Chang ◽  
Xingguang Sui ◽  
Long Xiao ◽  
Zhidong Guo ◽  
Yuming Yao ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Colloidal Dispersion ◽  
Oil Field ◽  
Sweep Efficiency ◽  
Profile Modification ◽  
Production Wells ◽  
Daqing Oil Field ◽  
Incremental Oil Recovery ◽  
Water Cut ◽  
Weak Gels

Summary The first large-scale colloidal dispersion gel (CDG) pilot test was conducted in the largest oil field in China, Daqing oil field. The project was initiated in May 1999, and injection of chemical slugs was completed in May 2003. This paper provides detailed descriptions of the gel-system characterization, chemical-slug optimization, project execution, performance analysis, injection facility design, and economics. The improvements of permeability variation and sweep efficiency were demonstrated by lower water cut, higher oil rate, improved injection profiles, and the increase of the total dissolved solids (TDS) in production wells. The ultimate incremental oil recovery (defined as the amount of oil recovered above the projected waterflood recovery at 98% water cut) in the pilot area would be approximately 15% of the original oil in place (OOIP). The economic analysis showed that the chemical costs were approximately U.S. $2.72 per barrel of incremental oil recovered. Results are presented in 15 tables and 8 figures. Introduction Achieving mobility control by increasing the injection fluid viscosity and achieving profile modification by adjusting the permeability variation in depth are two main methods of improving the sweep efficiency in highly heterogeneous and moderate viscous-oil reservoirs. In recent years (Wang et al. 1995, 2000, 2002; Guo et al. 2000), the addition of high-molecular-weight (MW) water-soluble polymers to injection water to increase viscosity has been applied successfully in the field on commercial scales. Weak gels, such as CDGs, formed with low-concentration polymers and small amounts of crosslinkers such as the trivalent cations aluminum (Al3+) and chromium (Cr3+) also have been applied successfully for in-depth profile modification (Fielding et al. 1994; Smith 1995; Smith and Mack 1997). Typical behaviors of CDGs and testing methods are given in the literature (Smith 1989; Ranganathan et al. 1997; Rocha et al. 1989; Seright 1994). The giant Daqing oil field is located in the far northeast part of China. The majority of the reservoir belongs to a lacustrine sedimentary deposit with multiple intervals. The combination of heterogeneous sand layers [Dykstra-Parsons (1950) heterogeneity indices above 0.5], medium oil viscosities (9 to 11 cp), mild reservoir temperatures (~45°C), and low-salinity reservoir brines [5,000 to 7,000 parts per million (ppm)] makes it a good candidate for chemical enhanced-oil-recovery processes. Daqing has successfully implemented commercial-scale polymer flooding (PF) since the early 1990s (Chang et al. 2006). Because the PF process is designed primarily to improve the mobility ratio (Chang 1978), additional oil may be recovered by using weak gels to further improve the vertical sweep. Along with the successes of PF in the Daqing oil field, two undesirable results were also observed:high concentrations of polymer produced in production wells owing to the injection of large amounts of polymer (~1000 ppm and 50% pore volume) andthe fast decline in oil rates and increase in water cuts after polymer injection was terminated. In 1997, a joint laboratory study between the Daqing oil field and Tiorco Inc. was conducted to investigate the potential of using the CDG process, or the CDG process with PF, to further improve the recovery efficiency, lower the polymer production in producing wells, and prolong the flood life. The joint laboratory study was completed in 1998 with encouraging results (Smith et al. 2000). Additional laboratory studies to further characterize the CDG gellation process, optimize the formulation, and investigate the degradation mechanisms were conducted in the Daqing field laboratories before the pilot test. A simplistic model was used to optimize the slug designs and predict incremental oil recovery. Initial designs called for a 25% pore volume (Vp) CDG slug with 700 ppm polymer and the polymer-to-crosslinker ratio (P/X) of 20 in a single inverted five-spot patten. Predicted incremental recovery was approximately 9% of OOIP.

X-Ray Computed Microtomography Studies of Fluid Partitioning in Drainage and Imbibition Before and After Gel Placement: Disproportionate Permeability Reduction

SPE Journal ◽  
2006 ◽  
Vol 11 (02) ◽  
pp. 159-170 ◽  
Author(s):  
Randall S. Seright ◽  
Masa Prodanovic ◽  
W. Brent Lindquist
Keyword(s):  
Porous Media ◽  
Permeability Reduction ◽  
Water Drainage ◽  
X Ray ◽  
Before And After ◽  
Production Wells ◽  
Computed Microtomography ◽  
X Ray Computed ◽  
Phase Water ◽  
Minimal Reduction

Summary X-ray computed microtomography (XMT) was used to establish why pore-filling Cr(III)-acetate-HPAM gels reduced permeability to water much more than to oil. Our results suggest that permeability to water was reduced to low values because water must flow through gel itself, whereas oil pressing on the gel in Berea sandstone or porous polyethylene forced pathways by dehydration—leading to relatively high permeability to oil. In very permeable sandpacks, data from other researchers support ripping or extrusion mechanisms for creating oil pathways. Our XMT studies provide interesting insights into imbibition and drainage processes in water-wet and oil-wet porous media even before gel placement. Many of our observations were consistent with conventional wisdom. However, some were unexpected. Residual wetting-phase (water) saturations in Berea were surprisingly low-valued in small pores. We attribute this to surface roughness caused by clay coating on Berea's pore walls, which allowed efficient water drainage from small pores during oil injection. Introduction Gels have often been injected into production wells in an effort to reduce water production without seriously damaging hydrocarbon productivity. To be effective, the gels must significantly reduce permeability to water while causing minimal reduction in permeability to oil. Many gels exhibit this disproportionate permeability reduction, but the property has not been as predictable as we would like. If the mechanism for this property were understood, gel treatments could be applied with greater reliability. To determine this mechanism for a Cr(III)-acetate-HPAM gel, we used XMT. As an important prelude to investigating gel behavior in porous media, XMT was used to characterize imbibition and drainage processes in water-wet and oil-wet porous media before gel placement.

scholarly journals Impact of the en echelon fault connectivity on reservoir flow simulations

2015 ◽  
Vol 3 (4) ◽  
pp. SAC23-SAC34 ◽  
Author(s):  
Charline Julio ◽  
Guillaume Caumon ◽  
Mary Ford
Keyword(s):  
Flow Simulation ◽  
Flow Simulations ◽  
Reservoir Flow ◽  
Production Wells ◽  
Time Requirements ◽  
Water Cut ◽  
Definition Of ◽  
Echelon Fault ◽  
The Impact

Limited resolution and quality of seismic data and time requirements for seismic interpretation can prevent a precise description of the connections between faults. We have focused on the impact of the uncertainties related to the connectivity of en echelon fault arrays on fluid flow simulations. We used a set of 100 different stochastic models of the same en echelon fault array. These fault array models varied in the number of relay zones, relative position of fault segments, size of overlap zones, and number of relay faults. We automatically generated a flow model from each fault array model in four main steps: (1) stochastic computation of relay fault throw, (2) horizon building, (3) generation of a flow simulation grid, and (4) definition of the static and dynamic parameters. Flow simulations performed on these stochastic fault models with deterministic petrophysical parameters entailed significant variability of reservoir behavior, which cannot always discriminate between the types of fault segmentation. We observed that the simplest interpretation consisting of one fault yielded significantly biased water cut forecasts at production wells. This highlighted the importance of integrating fault connectivity uncertainty in reservoir behavior studies.

Injection Rates - The Effect of Mobility Ratio, Area Swept, and Pattern

1961 ◽  
Vol 1 (02) ◽  
pp. 81-91 ◽  
Author(s):  
John C. Deppe
Keyword(s):  
Radial Flow ◽  
Initial Rate ◽  
Approximate Equation ◽  
Mobility Ratio ◽  
Rate Equations ◽  
Sweep Efficiency ◽  
Linear Flow ◽  
Flow Equations ◽  
Well Pattern ◽  
Injection Rates

Abstract A method is presented for calculating approximate injection rates in secondary recovery operations. The method can he applied to cases of unequal fluid mobilities, irregular well patterns and boundary patterns. The steady-state pressure distributions for the four flood patterns reported by Muskat and for five additional patterns reveal that most of the difference in pressure between the injection and producing wells occurs in regions around the wells which can adequately he described as regions of radial flow. This leads to a method of calculating injectivity by approximating the flood pattern with radial flow elements (or a combination of radial- and linear-flow elements for some patterns such as the direct line drive). Irregular and boundary patterns can also be approximated by radial and linear elements. Each of these elements can be described by radial- and linear-flow equations and the results combined as series flow resistances to give an approximate equation for the initial injection rate. The mobility ratio does not affect the initial rate; therefore, if the well pattern is one of those regular patterns for which theoretical rate equations have been derived for unity mobility ratio, the approximate initial rate equation can be improved by adjusting it to match the theoretical equation. The available theoretical rate equations are listed, including five new cases. As the flood progresses, the injectivity changes because in general the flood front will divide the pattern into areas of different fluid mobilities. Simple shapes can be assumed for the flood front so that both areas can be divided into radial- and linear-flow elements. Radial- and linear-flow equations are applied to these elements to account for the change in flow resistance behind the front. To calculate injection rates after breakthrough, it is necessary to know the sweep efficiency at breakthrough. Areal sweep data are available in the literature for a number of patterns, and sufficiently accurate breakthrough sweep efficiency can be estimated from these data if it is not otherwise available.

Comprehensive Approach to Tackle Systemic Failure in Gas Lift Valves in Pre Salt Wells

2021 ◽  
Author(s):  
Elaine Daniele M P C Real ◽  
Thiago Geraldo Silva ◽  
Otavio Borges Ciribelli ◽  
Tatiana Sanomya
Keyword(s):  
Failure Process ◽  
Comprehensive Approach ◽  
Fluid Composition ◽  
Artificial Lift ◽  
Production Wells ◽  
Production History ◽  
Early Failures ◽  
Water Cut ◽  
The Impact ◽  
Gas Lift

Abstract This work describes a comprehensive approach to tackle systemic failure in gas lift valves in pre-salt wells. Failure analyses in gas lift valves were performed after unexpected early failures leading to tubing-annulus communication. Understanding the root causes of this problem generates value for assets, increasing equipment life, preventing unnecessary workover, and reducing costs. Suspect failed valves are systematically removed from the wells, usually by slick-line workovers, and brought to an onshore workshop, where their integrity and mechanical functionality can be analyzed. The valve's run life, equipment model and manufacturer, annular fluid, flow through the gas lift valve, operational pressure and temperature, composition of reservoir fluids and solids deposition were verified. Besides, transient simulations were carried out to provide insights on the root causes of the failure. Also, a good understanding on how each valve works, including its engineering design, was necessary to thoroughly understand the failure process. The study of gas-lift injection valves early failure in pre-salt wells have been an excellent way to understand the life cycle of production wells before the need to start lift gas injection. That leads to a comprehensive understanding about the effects of the fluids left in annulus and have supported Petrobras in most effectively managing of well integrity and workover costs. The analysis incorporates the impact of oil production, water cut, completion type, annular fluid composition, anti-scaling fluid injection (composition and efficiency) and the differential pressure between the tubing of the annulus in the valve failure model. The composition of the deposit found inside the valves and the production history of the well were essential to assemble the puzzle of how the failure mechanism works. With the acquired knowledge, it has been possible to apply barriers to avoid future events of unwanted tubing-annulus communication arising from gas-lift valve failures. This article provides a methodology and examples for a most effective understanding of the gas-lift valves failure mechanisms and their root causes, which proved to be a valuable tool for the artificial lift design and for the planning of well operations. That has contributed to maximize equipment life, cost reduction and, at last, generating value for the company.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

The Precipitation of Si in AlCuSi Thin Films

1973 ◽  
Vol 31 ◽  
pp. 34-35 ◽  
Author(s):  
R. M. Anderson
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Heat Treatment ◽  
Solid Solution ◽  
Integrated Circuit ◽  
Copper Film ◽  
Solution Concentration ◽  
X Ray ◽  
Silicon Thin Films ◽  
Before And After

Aluminum-copper-silicon thin films have been considered as an interconnection metallurgy for integrated circuit applications. Various schemes have been proposed to incorporate small percent-ages of silicon into films that typically contain two to five percent copper. We undertook a study of the total effect of silicon on the aluminum copper film as revealed by transmission electron microscopy, scanning electron microscopy, x-ray diffraction and ion microprobe techniques as a function of the various deposition methods.X-ray investigations noted a change in solid solution concentration as a function of Si content before and after heat-treatment. The amount of solid solution in the Al increased with heat-treatment for films with ≥2% silicon and decreased for films <2% silicon.

A New Polyethylene Corrosion Protecting Coating with Ion Selectivity

2011 ◽  
Vol 314-316 ◽  
pp. 273-278
Author(s):  
Yu Hua Dong ◽  
Ke Ren ◽  
Qiong Zhou
Keyword(s):  
Ion Selectivity ◽  
Nano Particles ◽  
Ammonium Bromide ◽  
Linear Low Density Polyethylene ◽  
X Ray Diffraction ◽  
Sulfosalicylic Acid ◽  
X Ray ◽  
Chemically Modified ◽  
Before And After ◽  
Industrial Standards

Linear low density polyethylene (LLDPE) was chemically modified with grafting maleic anhydride (MAH) monomer on its backbone by melting blending. Nano-particles SiO2 was modified by cationic surfactant hexadecyl trimethyl ammonium bromide (CTAB) and anionic surfactant sulfosalicylic acid (SSA) and added to PE coating respectively. Measurement of membrane potential showed that the coating containing modified SiO2 nano-particles had characteristic of ion selectivity. The properties of the different coatings were investigated according to relative industrial standards. Experimental results indicated that PE coating with ion selectivity had better performances, such as adhesion strength, cathodic disbonding and anti-corrosion, than those of coating without ion selectivity. Crystal structure of the coatings before and after alkali corrosion was characterized by Fourier transform infrared spectra (FTIR) and X-ray diffraction (XRD). Structure of the coating without ion selectivity was damaged by NaOH alkali solution, causing mechanical properties being decreased. And the structure of the ion selective coatings was not affected.

scholarly journals Synthesis of Novel Arginine-Based Flame Retardant and Its Application in Lyocell Fabric

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3588
Author(s):  
Jiayi Chen ◽  
Yansong Liu ◽  
Jiayue Zhang ◽  
Yuanlin Ren ◽  
Xiaohui Liu
Keyword(s):  
Fourier Transform ◽  
Heat Release ◽  
Flame Retardant ◽  
Photoelectron Spectroscopy ◽  
Fourier Transform Infrared ◽  
Ftir Analysis ◽  
Excellent Thermal Stability ◽  
X Ray ◽  
Cone Calorimeter Test ◽  
Before And After

Lyocell fabrics are widely applied in textiles, however, its high flammability increases the risk of fire. Therefore, to resolve the issue, a novel biomass-based flame retardant with phosphorus and nitrogen elements was designed and synthesized by the reaction of arginine with phosphoric acid and urea. It was then grafted onto the lyocell fabric by a dip-dry-cure technique to prepare durable flame-retardant lyocell fabric (FR-lyocell). X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) analysis demonstrated that the flame retardant was successfully introduced into the lyocell sample. Thermogravimetric (TG) and Raman analyses confirmed that the modified lyocell fabric featured excellent thermal stability and significantly increased char residue. Vertical combustion results indicated that FR-lyocell before and after washing formed a complete and dense char layer. Thermogravimetric Fourier-transform infrared (TG-FTIR) analysis suggested that incombustible substances (such as H2O and CO2) were produced and played a significant fire retarding role in the gas phase. The cone calorimeter test corroborated that the peak of heat release rate (PHRR) and total heat release (THR) declined by 89.4% and 56.4%, respectively. These results indicated that the flame retardancy of the lyocell fabric was observably ameliorated.

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