bluuebunny/crossref_metadata_2025_split huggingface dataset:
In-Depth Permeability Damage by Particle Deposition at High Flow Rates
Authors: Veerapen J. P. , Nicot B. , Chauveteau G. A. 
Published: December 2007

Abstract
This paper reports the main results of a study of the physics of in-depth particle deposition inside porous media at high velocities. This study was motivated by the need to determine the equations relevant for the deposition of "large" micronic-size particles to introduce them into a numerical simulator and thus to be able to predict more reliably well injectivity decline. Indeed, as distance from the well decreases, velocity increases and convection becomes dominant over brownian diffusion at smaller and smaller length scale. This changes drastically the deposition laws and consequently those of permeability damage. Indeed, at high velocities, convection is expected to reduce drastically particle deposition density near pore throats by two mechanisms we refer to as hydrodynamic shadowing and surface entrainment. Our analysis shows that hydrodynamic shadowing may be active up to relatively large distances from the wells for micronic-size particles. A direct consequence is that equations based on convective diffusion at pore length scale are irrelevant. Indeed, hydrodynamic shadowing hampers deposition of new arriving particles downstream from already deposited ones, leading to a very significant reduction in maximum deposition density. This prediction is in good agreement with our experimental results. The second mechanism, namely surface entrainment, is limited to much smaller distances from the wells but also contribute to reducing injectivity damage. In this surface entrainment regime, particles can move on non-negligible distances near the pore throats before being attached by attractive surface forces. As a result, deposition probability in pore throats is smaller than predicted from conventional analysis and decreases with velocity. These two mechanisms may explain why the formation of internal cakes, which is initiated by pore bridging, is often observed at low velocity but rarely in the high velocities range. Such a drastic effect of flow velocity suggests that, in field injections, internal cakes may be initiated only in-depth far inside the reservoir, grow up towards the well and then cause very severe and irreversible injectivity damages. A third point, particularly important for modeling permeability damage kinetic, is that the particle deposition flux is several times higher onto pore throats than the mean value. Such a result is expected only in a converging flow but not in a flow over a collector. This confirms that the prediction of transport phenomena requires the use of a dual porous medium model such as the Grain-and-Pore-Throat model which accounts for both flow-over and flow-through situations which are obviously two characteristics of flows through porous media.
Laboratory Device for Testing of Delayed-Breaker Solutions on Horizontal Wellbore Filter Cakes
Authors: Todd Brad , Murphy Rob 
Published: December 2007

Abstract
Many high-permeability, soft sandstone formations are completed with horizontal wellbores. In these formations, completions are typically openhole with screens or screens combined with gravel packs. The drill-in fluid filter cake is left in place until the completion operations are finished. At that time, a cleanup solution is pumped to remove the filter cake from the wellbore face. These cleanup solutions can be acids, chelating agents, oxidizers or enzyme treatments, or combinations of these materials. A common disadvantage of these treatments is that they are highly reactive and may remove the filter cake at the point of circulation before the treatment can be placed over the entire openhole interval. This is especially true for the cleanup solution used to address the bridging particles in drill-in fluids. A need exists for cleanup solutions that have a delayed effect on filter-cake integrity, allowing the cleanup solution to be circulated across the interval before leakoff to the formation becomes a problem. Ideally, the treatment's reaction with the filter cake would commence when the entire solution is in place and continue until the filter cake is uniformly removed. If a sufficient delay is possible, the breaker solution can be placed with a gravel pack. Break times for this situation would range from 4 to 24 hours, depending on the need for fluid-loss control during subsequent pipe trips.
Conducting breaker tests manually for this type of delay could be extremely time-consuming and prone to variations between tests. Repeatability of the filter-cake deposition becomes even more important during sensitivity testing of the various components of a proposed cleanup solution. Clearly, automating the filter-cake construction and breaker solution testing would be advantageous. Fortunately, commercially available dynamic mud-filtration testing equipment can provide much of the needed automation capability. This paper discusses the additional modifications necessary for converting the instrument into the automated, delayed-breaker testing device required. Example test results are given for long-delayed breaks of water-based drill-in fluid filter cakes showing the sensitivity of the break time as a function of various formulation and testing parameters.
Polymer Sealant for Unwanted Gas in Openhole Gravel-Pack Completion
Authors: Bach T. , Wennberg K. E. , Mebratu A. , Hendriks W. P. , Warren J. M. , Rolfsvaag T. 
Published: December 2007

Abstract
In September 1999, Statoil completed Well A-13 in the Are formation ofthe Heidrun field with a 130-m openhole gravel pack. After only a few days of production, a high gas-to-oil ratio (GOR) required the operator to shut the well in. Free gas was believed to be flowing from a gas-filled sand located immediately above the 9 5/8-in. casing shoe. Production analysis indicated a high-permeability flow channel between this layer and the upper zone of the gravel pack. The operator and a major service company jointly evaluated different chemical gas shut-off systems and several placement methods. A new generation of organically crosslinked polymer gel technology was selected. In addition, the operator desired that the gel be injected with open-ended CT and without mechanical packers to reduce operational risk. Therefore, a chemical diversion system was required for protecting the lower zone.
In February 2000, a temporary blocking agent consisting of a crosslinked hydroxypropyl guar polymer was placed in the lower part of the gravel pack. Then, the permanent sealant was injected into the gas-producing zone. After 72 hours, CT was used to wash the well. Finally, the well was lifted with production gas. The entire operation was completed in a single run with CT.
Currently, the well is producing oil at a rate of350 Sm3/d and no significant free gas. Production paid for the cost of the sealant treatment within 1 month. Additionally, this treatment prevented the operator from having to recomplete and sidetrack the well. This paper describes the well's gas-flow mechanism, the polymer gel systems used for sealing the gas-flow zone, the placement technique, and the operational aspects of the selective gas shut-off treatment.
Recovery Increase through Water Flooding with Smart Well Technology
Authors: Brouwer D. R. , Jansen J. D. , van der Starre S. , van Kruijsdijk C. P. J. W. , Berentsen C. W. J. 
Published: December 2007

Abstract
Water flooding is a frequently used technique to increase oil recovery after primary depletion. The presence of high permeability zones can have a large influence on the recovery, because they can cause early water breakthrough and trapping of by-passed oil. Smart well technology gives us the opportunity to counteract these effects by imposing an appropriate pressure or flow rate profile along the injection and production wells. In the current study we focus on water flooding with fully penetrating, smart, horizontal wells in 2 dimensional, horizontal reservoirs with simple, large-scale heterogeneities. The water flood is improved by changing the well profiles according to some simple algorithms that move flow paths away from the high permeability zone in order to delay water breakthrough. For all cases where early water breakthrough plays a role, it was possible to improve the water flooding process with these simple algorithms. For all these cases acceleration of production was possible. The increase in ultimate recovery obtained is very much dependent on total production time allowed. The shorter this time, the better the improvement in recovery will generally be. The increase in recovery obtained by applying the optimization algorithm varied between 0% - 20%. The delay in breakthrough time achieved by our optimization routine varied from 7-168 %. Our algorithms result in flow profiles that do not change in time. Both results from our own study and from literature show that time-varying flow profiles can at least further accelerate production. The general principle behind optimization in our cases was to reduce the difference in time of flight from injector to producer as much as possible.
Drainage Area for Horizontal Wells With Pressure Drop in the Horizontal Section
Authors: Saavedra N. F. , Reyes D. A. 
Published: December 2007

Abstract
In general, a horizontal well is more productive than a vertical well, due to the fact that there is a larger area of contact with the reservoir and that there is less pressure drop per unit of length in the production section.
The two main factors to obtain more reserves in a reservoir are the increase in drainage area or an increase of the recovery factor using some enhanced recovery method. The productivity as well as the drainage area of a horizontal well may be limited by the pressure drop within the wellbore, especially when the pressure drop is comparable to the drawdown from the reservoir to the wellbore. Over the past few years, horizontal well technology has acquired quite significant importance and thousands of wells are drilled around the world every year, which is why there is a need for more information on the factors that affect pressure drop within the well.
Total pressure drop in horizontal wells has been analyzed in terms of four separate effects: wall friction, flow acceleration, perforation roughness, and fluid mixing.1 Thus, the pressure drop in horizontal wells is made up of a gravity term, a frictional term and another due to flow acceleration.2
The literature available about calculating drainage areas of horizontal wells only covers geometric methods, which assume that the horizontal well drains an elliptic area or a combined area made up of a central rectangle and two semicircles on the ends. 2,3
This paper proposes an expression to calculate the drainage area of horizontal oil wells that produce at high reservoir flow rates, exhibiting a frictional pressure drop throughout the wellbore between 15 to 60% of the reservoir drawdown at the heel of the well.
Artificial Neural Networks Applied to the Operation of a Fluid Catalytic Cracking (FCC) Unit
Authors: Pérez José R. , López Roberto , Dassori Carlos G. , Ranson Aaron 
Published: December 2007

Abstract
A model, based on artificial neural networks (ANN), for a fluid catalytic cracking (FCC) unit is developed.
The ANN model of the plant was developed using process and laboratory data directly from a refinery data acquisition system. And it used to predict process variables and estimate several product quality properties. The empirical model was accurate up to 98.0 % when tested on experimental data not used during training, which is an outstanding performance.
The present paper shows how a neural network, three-layered perceptron, can be used effectively to simulate the actual behaviour of refining units, specifically a fluid catalytic cracking (FCC) unit.
Prediction of Formation and Downhole Pressures by Using Computer Intelligent Calculation and Analysis
Authors: Zhou Lei , Zhou Kaiji 
Published: December 2007

Abstract
Formation pressure, failure pressure, wellbore collapse pressure and surge/swab pressure are important basis of pressure control in drilling progress, wellbore stability, balanced and unbalanced drilling, and well structural design. They are also fundamental data used in Drilling Engineering Design and Construction. Comprehensive well logging (sound logging, density logging, gamma logging) can be collected and handled intellectually by this system. Formation pressure, failure pressure, wellbore collapse pressure, and rock characteristic factor (dynamic elastic modulus, static elastic modulus, Poisson ratio, internal friction angle, effective stress modulus, shear strength, compressing strength, tensile strength) were predicted by this system. In this paper, calculation and analysis system to predict transient-state, pseudo-transient-state and steady-state pressure fluctuations were established by using theory of elastic liquid column and rigid liquid column (Three types of fluids, Bingham fluid, power law fluid, H-B fluid, were included in this system). This prediction system has the following features: Capacity to collecting and handling well logging curves intelligently; High accuracy to predict; Output pressure curves and pressure gradient curves also regression results. This prediction system can provide Drilling Engineering Design, working-on, balanced and unbalanced drilling, overflow and leaking control, safe trip in and trip out velocity, and wellbore stability with reliable data.
Well Impairment During Sea/Produced Water Flooding: Treatment of Laboratory Data
Authors: Bedrikovetsky P. , Marchesin D. , Shecaira F. , Serra A. L. , Marchesin A. , Rezende E. , Hime G. 
Published: December 2007

Abstract
Severe fall of injectivity happens with the reinjection of produced water which contains oil droplets and solid particles, with the injection of sea water in offshore fields which contains organic and mineral inclusions, and in a general case of injection of a poor quality water.
The mathematical model contains two empirical functions - filtration coefficient versus concentration of deposited particles and velocity and formation damage function versus concentration of deposited particles. Two inverse problems for determination of these two functions from the laboratory coreflood test are formulated.
The first problem is determination of a filtration coefficient from the concentration history on a core outlet. The algorithm of solution is given, and the laboratory data treatment is presented. The second problem is determination of a formation damage function from the pressure drop history on a core. These two methods allows to determine from laboratory test the information necessary for prediction of well impairment.
Improvement Tools To Solve Quality Deviation Problems
Authors: Grzona Gabriel C. 
Published: December 2007

Abstract
One of the fundamental requirements for success in making a process function under the concepts of Total Quality Management is to ensure that it is capable of operating with a minimum variability with respect to the quality specification objectives of the products which are produced by the process.
Quality may be broadly defined in many ways, but from a strictly technical viewpoint Quality Engineering must be understood as the skill to reduce systematically the variability of the processes. It is in this context in which the Continuous Improvement Tools and particularly the Statistical Process Control, are essential for achieving World Class Quality Management.
A program for the application of these tools can detect assignable causes, limit waste, improve the quality of the products, reduce or eliminate reprocessing and, even more important, establish a new process of systematic work toward continuous improvement.
The present job shows both theoretically and practically how to apply these tools to solve quality deviations.
Case Study: Improvement of Jet A1 quality in a Hydrocracking unit.

Background
During the last few years quality systems have become established as a fundamental part of business strategies to increase the productivity and competitiviness of companies. Total Quality Managements focus their attention on their most precious treasure : "THE CUSTOMER". If a product is to meet the client s acceptability criterion its quality must inexorably be stable and reproducible, although even then there is no total guarantee that the product will have the same quality. All processes have a certain degree of variability : when the latter is "natural" it is due to the cumulative effect of small effects which are known as "inevitable causes". In Statistical Control jargon this is referred to as a system of accidental or random causes.
A system which performs with only accidental causes is said to be under "Statistical Control".
On the other hand if "assignable causes" appear in a process, that is, those that derive from a perfectly detectable source of lack of control, then the use of the continuous improvement tools is fundamental for their correction.
Evolution of Field Rejuvenation
Authors: Singh Kasarie 
Published: December 2007

Abstract
At the state oil company of Trinidad and Tobago, (Petrotrin) and its predecessor companies, Field Rejuvenation has evolved through time from single well targets to the more highly detailed and complex field reservoir characterization project currently underway.
Initially single well target selection would be done by individual engineers operating their specific field. Generally, the benefit of these actions were not long term and did not significantly affect or arrest the declining production trends. At a more formal level there were studies undertaken in the process of the implementation a secondary or enhanced oil recovery project. This had the effect of arresting field declines and improving overall recoveries in the target fields.
The foregoing activities were carried out by the operating companies of the day. In the late eighties because of limited capital resources, a program of leasing blocks of idle wells to small independent local operators was initiated. This program proved successful in increasing indigenous oil production from idle assets as well as generating positive cash flows. It was therefore expanded and has since included farmouts and joint-venture arrangements with foreign companies participating also.
Currently Petrotrin is concluding a detailed field reservoir characterization study of one of its most mature fields on land which began production in 1913. The preliminary results have demonstrated the crucial role of reservoir characterization in evaluating the true potential of mature fields, and its potential for increasing production even from these fields.
U.S. International Minerals Policy in the 1970's (These are the personal views of the author and do not necessarily represent the policy of the U.S. Government)
Authors: Garten Jeffrey E. 
Published: December 2007

Garten, Jeffrey E., former member, Policy Planning Staff U.S. Department of State Staff Member, Economic Policy Group Executive Office of the President

Abstract
An appraisal of the role played by imports of critical mineral materials in shaping U.S. foreign policy during the current decade, with particular emphasis on the importance of energy particular emphasis on the importance of energy and minerals in U.S. trade patterns with economically less developed nations.

Introduction
This paper will discuss three elements of U.S. international minerals policy - the international minerals environment, the government's objectives, and the imperatives for U.S. policies

A. The Environment
In the last several years, we have seen first, tight supply situations and soaring prices for a number of critical industrial raw prices for a number of critical industrial raw materials; and, then, rapidly declining prices; we have witnessed the determined and economically disruptive action of the OPEC cartel; we have experienced recurrent resort to unilateral barriers to raw material exports; and we have heard predictions of natural resource exhaustion.
These events have, of course, colored the public debate over U.S. raw materials policy. public debate over U.S. raw materials policy. But the emerging U.S. government policy itself is less a response to any particular event or scare in the last year or two, than to longer term trends which are occurring in the international economy and in the minerals markets.
Let us set aside predictions of natural exhaustion of resources. The government's feeling is that if resource scarcity occurs it will be because of improper public policies and not natural depletion. The following considerations, however, are strongly influencing U.S. foreign economic policy.
First, it is quite possible that several structural changes are occurring in the world economy which will have a major impact on minerals markets. Many economists are concerned that a de facto synchronization of the business cycle in industrial countries will result in recurring and possibly more severe business cycles than the recent period we have just been through. The result would be reflected in greater global demand surges and contractions and, hence, wider price swings. There is a concern also that we have entered a period of structural inflation which among other things will continue to encourage commodity speculation and continue to bid up raw material prices. There is the growing interdependence among many countries, which means that we are all drawing on one global resource base; insures that even many temporary economic disturbances will be transmitted quickly from one economy to the rest; and makes foreign policy reach to our gas pumps, our food counters, and the aluminum pumps, our food counters, and the aluminum siding on our garages. And there have been major changes in the relative economic relationships between countries.
How Fluid and Rock Properties Affect Production Rates in a Heavy-Oil Reservoir Cerro Negro, Venezuela
Authors: Lugo R. Garcia , Eggenschwiler M. , Uebel T. 
Published: December 2007

Abstract
In Cerro Negro, extra-heavy crude (8.5° API) is produced using horizontal wells via cold production from Miocene Morichal Member sands. Production is from an average depth of 3,000 ft, with an in-situ viscosity of around 2,000 cp (@140° F). The Morichal Member is sub-divided into three informally defined units: Upper, Middle and Lower. Reservoir quality is excellent, with porosity around 32% and permeability in the order of 10 Darcies.
The top of the Morichal sands varies in depth from 1,500 to 4,000 ft. The depth of the sand, coupled with 700-900 ft reservoir thickness, results in significant changes in pressure and viscosity across the block. Pressure varies from 900-1,300 psi and viscosity from 1,500-4,000 cp. Pressure and viscosity variations, when modeled using a single well simulation grid, significantly affect well productivity and ultimate recovery. Changes in viscosity and pressure, assuming constant pay thickness, and permeability, result in predicted ultimate well recoveries that vary from 1.5 to 6 million barrels of oil per well. Efforts to history match horizontal wells that have been on production for around one year have been successful. These results give a better understanding of how fluid and rock properties are influencing extra-heavy crude oil recovery, which allows a better prediction of well productivity and full-field development plans.