bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigating Electrical-Impedance Tomography as a Technique for Real-Time Saturation Monitoring
Authors: Stacey Robert W. , Li Kewen , Horne Roland N. 
Published: March 2009

Summary
3D electrical-impedance tomography (EIT) is a technique that has the potential to provide estimates of reservoir saturation at multiple scales by determining the resistivity distribution within the subsurface. In theory, EIT is well suited for researching oil and brine systems because of the large contrast in resistivity between the two phases. Here, in our initial laboratory investigation, we have applied the EIT technique to measure the saturation distribution of water within a core.
The initial EIT experiment presented here used a Berea-sand-stone core with 48 electrodes attached in three rings of 16. The core was open to the atmosphere, with saturation occurring by natural imbibition and desaturation occurring by evaporation. The voltage-potential field was measured by applying a direct-current (DC) pulse across the core and measuring the voltage potential at all electrodes, essentially applying the four-wire resistance technique over all electrodes in turn. The result was a data set that embodies the resistivity distribution within the core, and, by inversion, the resistivity distribution was reconstructed, which allowed for the inference of the saturation.
The data processing was accomplished by using the Electrical Impedance Tomography and Diffuse Optical Tomography Reconstruction Software (EIDORS) toolkit, which was developed for application to this nonlinear and ill-posed inverse problem. The procedure uses a finite-element model for forward calculation and a regularized nonlinear inverse solver to obtain a unique and stable inverse solution.
Experiments have indicated that EIT is a viable technique for studying the displacement characteristics of fluids with contrasting resistivity and is capable of detecting displacement fronts in near to real time. The current system is also a quantitative technique able to measure saturation distributions accurately between 15% &lt; Sw &lt; 65% in a Berea sandstone core. These limitations were imposed because of connate-water connections to the electrodes and ion-mobility effects caused by the DC voltage source. It is anticipated that the applicability of EIT will increase with the implementation of an alternating-current (AC) voltage source.
Estimation and Removal of Tidal Effects From Pressure Data
Authors: Zhao Yong , Reynolds Albert C. 
Published: March 2009

Summary
We consider field pressure data from two wells, one offshore and one onshore. The onshore well is shut-in and experiences only a very small pressure decline due to interference, whereas in the offshore case, the late time buildup data appear to be severely corrupted by ocean tidal effects. The objectives in both cases are to determine the tidal signal that can be used to estimate formation compressibility and to remove the tidal signal from the measured data.
For the onshore well, we use a Savitzky-Golay (SG) filter to smooth the pressure data. Subtracting the smooth data from the measured signal yields a modified signal that ideally represents the earth tidal signal plus measurement error. A s the main harmonic components of the earth tidal signal are known, we perform a least-squares fit of the modified pressure data with a series of sines and cosines that contain only the known frequencies of the earth tide. By subtracting the series obtained by least-squares fitting from the true signal, we remove the effect of the earth tide.
In the offshore case, the time span of data that are severely affected by tidal effects is too short to use the SG filter with confidence. As the reservoir pressure change due to the tides is well-approximated by a damped and delayed version of the seafloor response, a least-squares fit of the data with a function that follows the underlying buildup trend plus an attenuated-delayed response of the measured seafloor pressure trace allows one to obtain a good estimate of the attenuation factor and time delay so that the tidal component of the bottomhole pressure change can be determined and removed from the measured pressure.
Flow of a Polyacrylamide/Chromium Acetate System in a Long Conduit
Authors: McCool Stan , Li Xianping , Wilhite G. Paul 
Published: March 2009

SummaryTypical gelled-polymer treatments to treat fractured rock consist of injecting in-line-mixed gelant into the reservoir for times usually much longer than the bulk gel time of the gelant. Flow experiments were conducted to determine the effect of shear on the flow properties of the gelant for durations greater than the bulk gel time. In-line-mixed gelant was injected through a 1,031-ftlong tube to simulate a fracture treatment. Flow resistance increased down the tubing to steady values indicating gelation of the flowing system. Similar flow experiments were conducted by injecting preformed gel through the tubing. Flow resistances decreased down the tubing to steady values, indicating breakdown of the gel structure. Steady flow resistances of the downstream sections were higher during the injection of in-line-mixed gelant compared to injection of preformed gel, and both were much lower than literature values determined where preformed gel was injected through short fractured rocks and short lengths of tubing. Gel samples underwent syneresis after they were formed during shear flow in the tubing and in a rheometer. Interpretations of flow-resistance data from the injection of in-line-mixed gelants and preformed gels in long tubing are presented.
A New Splitting Scheme and Existence of Elliptic Region for Gasflood Modeling
Authors: Dutra T. A. , Pires A. P. , Bedrikovetsky P. G. 
Published: March 2009

Summary
Analytical models of gasflooding are important for enhanced-oil-recovery (EOR) screening, for interpretation of laboratory data, and for streamline modeling. Introduction of two Lagrangian coordinates linked with one of the components and with the overall two-phase flux results in splitting the compositional model into an auxiliary system and an independent scalar equation. The number of equations in the auxiliary system is less by one if compared with the compositional model, making analytical modeling possible for more practical cases. The auxiliary system contains only thermodynamic functions and is independent of transport properties. Therefore, phase transitions and minimum miscibility pressure for gas injection are also independent of transport properties. The new splitting method is applicable for both self-similar solutions of continuous gas injection and nonself-similar solvent-slug problems. Analytical solution for four-component oil displacement by a nitrogen-based solvent was obtained using the splitting technique. The compositional two-phase model contains an elliptic region if and only if an elliptic region is also present in the auxiliary system. Calculations for several four-component mixtures exhibit existence of an elliptic region in compositional modeling.
Modeling a Finite-Length Sucker Rod Using the Semi-Infinite-Wave Equation and a Proof of Gibbs' Conjecture
Authors: DaCunha J. J. , Gibbs S. G. 
Published: March 2009

Summary
In this paper, we study semi-infinite-spatial-domain wave equations modeling the real-world problem of longitudinal waves propagating along a long, slender, homogeneous elastic rod of finite length. A practical conclusion from the paper is that precision of the downhole card can be increased by improving the accuracy of the friction law in the wave equation. To conclude, we provide a rigorous proof of Gibbs' theorem and illustrate its validity with an existing well.
Where is the Gap? Is it in More Reservoir Engineers or in Leveraging New Skills and Workflows that Enhances Individual Productivity?
Authors: Amudo C. , Graf T. 
Published: March 2009

Abstract
The primary functions of a reservoir engineer include estimation of hydrocarbons in place, the evaluation of the recovery factor and the scheduling of the recovery. These roles are central in meeting the extremely complex challenges of the life-cycle development of hydrocarbon resources.
These challenges have now assumed gargantuan proportions because of mature assets requiring more attention to squeeze the last drop of oil from them, complicated accumulation needing ingenious solutions to make them profitable, high development costs demanding greater attention to details to reduce costs and unprecedented prices that has made otherwise marginal fields more attractive to develop. Throw also in the mix the heightened sense of environmental issues, unconventional hydrocarbon resources, competing alternative sources of energy, strict compliance with regulatory bodies and uncertain political situations in most of the growth basins and you might have sympathy for those crying for more reservoir engineers in the industry.
The fact is that our traditional deterministic approach of working is people intensive and it has started to fail the industry. Therefore, recruiting many more engineers to meet the present challenges can only fuel the vicious cycle of hire and fire approach that has made our industry less attractive in the past. We need to embrace new workflows based on established statistical concepts like neural networks and experimental designs that move the focus from people to computers. These new workflows also enable greater flexibility in data handling, ensure consistency in uncertainty quantification and give results in continuous distributions that can be sampled rapidly using statistical techniques like Monte Carlo.
This paper describes how statistical techniques can help in many core reservoir engineering roles like surveillance, history match and reservoir management. In addition, it presents relevant examples that illustrate the successful application of these concepts in the industry including a possible automation of integrated reservoir studies.
Reservoir Simulation Study on Improvement of Waterflooding Effect for a Naturally Fractured Low Permeability Field in Daqing, China: A Successful Case
Authors: Pu Hui , Wang Guofeng , Li Yingxin 
Published: March 2009

Abstract
Xinzhao field, developed in 2000, is one of the major naturally fractured reservoirs of Daqing oilfield, China. Production is obtained from the Putaohua(P) sandstone formation at an average depth of 1,338m. After several years' waterflood development, the development effect was deteriorating, many wells were becoming to be stripper wells, and watercut increased greatly, even some wells were seriously watered out. In order to improve the development effect of Xinzhao oilfield, a reservoir study was made in sufficient depth to understand past performance and to develop a long-range development plan, and the proposed pattern modification was performed in Xinzhao oilfield.
The purpose of the study is to develop an optimization strategy for waterflood performance. The first step in the process is to better understand the reservoir. One of tools used are Sourceless Microseismic Fracture Monitoring Technology. The Sourceless Microseismic Fracture Monitoring tool is used to determine the characteristics of fractures. The results of Sourceless Microseismic Fracture Monitoring Technology show that the orientation of most of fractures is east-west.
The second step is to analyze the past waterflood production performance to know the development characteristics of existing pattern(inverted nine-spot well pattern). The production rate decline is analyzed, and the reasons causing the current poor development effect are identified. The third step is to develop optimization and surveillance recovery strategies. Reservoir simulation approaches are utilized to optimize the well pattern. The recommended plan is pattern modification with strategy of implementing conversions step by step.
A field test of waterflood pattern realignment was carried out. This paper presents the results of pattern modification, and the following tracking and modifications strategies. This field test in Xinzhao field is successful and also is an excellent opportunity to demonstrate the method to improve the development effect of naturally fractured reservoir.
Horizontal Well Sectional Frac Technique with Dual-Retrievable Packers in Daqing Oilfield
Authors: Yaning Liang , Qingfeng Yue , zhenhuan Zhang , Qingzhong Li , Jianhua Xie , Li Ban , Borui Li 
Published: March 2009

Abstract
Horizontal well technology is a technological revolution in oil industry, and it is one of the most important methods of thick layer sustainable production and marginal low permeable formation exploitation in Daqing Oilfield. It is commonly believed that fracturing is an effective way to recover oil from thin, low porosity and low permeability sands. However, the existing frac technique in the horizontal wells - the limited entry frac is a kind of commingled frac method that cannot guarantee the fractures' opening and extension uniformly owing to heterogeneity formation. A novel sectional frac technique with dual-retrievable packers by separately stimulating the specific intervals one by one has been developed to recover low permeable reservoirs in the horizontal wells. Sectional frac string chosen includes high pressure, high temperature tools which have been used in several wells application as well as long term tested in a laboratory environment to differential pressures of 7300 psi at 190 ° F with functions of stuck-preventing, stuck-releasing and reverse sand flushing. Five intervals treatment can be done in one trip.
Up to now, this technique has been applied on 55 horizontal wells in Daqing Oilfield and 281 intervals were fractured in the field. It usually takes one to three days to frac a horizontal well according to the numbers of target reservoirs. The initial oil production after using the sectional frac technique in horizontal wells is 5.7 times higher than that in vertical wells, and 1.04 times higher than that by using the limited entry frac technique in horizontal wells. The current oil production after using the sectional frac technique in horizontal wells is 4.3 times higher than that in vertical wells, and 1.72 times higher than that by using the limited entry frac technique in horizontal wells. Field runs and lab testing have confirmed that sectional frac technique is a viable option in recovering low permeable reservoirs in the horizontal wells.
Case History: Successful Application of Combined Rotary-Jetting and MLT to Stimulate Dual-Lateral Producer in Ghawar Field
Authors: Al-Buali Muhammad H. , Al-Arnaout Ibrahim H. , Al-Shehri Ayed M. , Haldar Surajit , Al-Driweesh Saad M. 
Published: March 2009

Abstract
The implementation of multilateral wells in Saudi Aramco, and in the southern area of Ghawar field in particular, is being increased for production and cost optimization. Accessing and stimulating individual laterals is a challenge that requires an optimum design in terms of cost, application and efficiency.
This paper will describe a unique utilization of a combined high energy rotary-jetting tool with a multilateral tool (MLT) to access and treat a dual-lateral oil producer in the southern part of Ghawar field. The main purpose of utilizing this combined tool was to acid wash the Arab-D horizontal section of both laterals with nitrified hydrochloric acid using coiled tubing (CT). The objectives of the treatment were to increase flowing bottom-hole pressure (FBHP), remove formation damage and return the well to production. The rotary-jetting tool is a high energy jetting tool that maximizes performance of treatment fluids while minimizing the need for large acid volumes. It can be run with the MLT to enable accessing and stimulating both laterals in a single trip.
The implementation of the combined tool resulted in accessing and stimulating both laterals successfully. The well was returned to production at a rate of 11,000 barrels of oil per day (BOPD). The volume of acid was reduced due to utilizing the rotary-jetting tool, which maximized fluid treatment performance. This paper will cover the whole cycle of candidate selection, job design, execution, post job evaluation and conclusion.
Attracting Top Students to Study Petroleum Engineering: Curtin University
Authors: Smith L. C. , Evans B. J. 
Published: March 2009

Abstract
Over the past 20 years, two of the main methods of training new students in petroleum engineering at Curtin University have been to provide a Bachelor of Engineering in chemical engineering with a minor/major in petroleum engineering, or to offer a Masters in Petroleum Engineering as a conversion course for graduates of an appropriate science or engineering discipline.
When the industry picks up strongly and there becomes a shortage of skilled professional engineers, the industry employs anyone who has skill and experience. A knee-jerk reaction is to turn to academics, enticing them with attractive salaries, thereby depleting the stocks of quality petroleum engineering teachers. This results in a weakening of the education system which is expected to provide the future quality graduates.
Curtin University Department of Petroleum Engineering is no exception. Our first step however was to base the department on high quality research, so that we were not dependent upon short term income from industry. The next step was to change the Masters teaching base to semester rather than block teaching. This allowed faculty to enter long term research contracts and to teach over the full semester period. Additionally we extended our Masters program to 2 years in duration to make it more attractive to international students who could subsequently apply for permanent residency in Australia following their studying. As a result applications to the Masters program has increased by 60%. Additionally, we have developed a new Master's entry point via a one year Post Graduate Diploma course, which then allows international students to enter the Masters program with the desired prerequisites- this has also removed Australian visa restrictions, making it financially prohibitive for students coming from some countries. The result has been a return to stability and optimism with faculty and staff who want to educate tomorrow's engineers.
Thermodynamic Criteria and Final Results of WAG CO2 Injection in a Pilot Project in Croatia
Authors: Novosel D. 
Published: March 2009

Abstract
The remaining oil reserves in Croatian oil fields amounted to 11.0 million cubic meters at the end of 2007. This, together with high oil prices on the world market, represents a good basis for the implementation of enhanced oil recovery methods. Between 1978 and 1991, detailed laboratory research of carbon dioxide usage for oil displacement was performed. That research, coupled with simulation studies, has proved that water alternate gas – WAG process achieves the best oil recovery from Croatian oilfields (e.g. Ivanić oilfield).
The CO2 pilot project on the Ivanić oilfield started in 2001 by injecting salt water into the reservoir in order to increase reservoir pressure. The injection of carbon dioxide lasted between 2003 and 2006. Final results and in situ data from the field will be presented in the paper. During the injection of carbon dioxide into the reservoir, some thermodynamic changes occurred in the tubing string as well. The most important factors during CO2 injection are the knowledge of CO2 physical characteristics and thermodynamic conditions during the injection. PT conditions during the CO2 injection on the pilot project have been measured and will be presented in the paper. Based on the results of the pilot project, a decision to set up the first Croatian full-field EOR project on Croatian oilfields was made.
Transient Pressure Behavior for a Reservoir with Continuous Permeability Distribution in the Invaded Zone
Authors: El-Khatib Noaman A. F. 
Published: March 2009

Abstract
A mathematical model is presented for a reservoir with a continuous permeability distribution in the invaded zone. An analytical solution of the system was obtained in Laplace space. Solutions in real time space for the pressure and pressure derivative are obtained by numerical inversion of the Laplace transform using Stehfest algorithm. Solutions were obtained for infinite reservoirs and for finite reservoirs with closed and constant pressure outer boundaries. The permeability in the invaded zone varies from a skin permeability KS at the wellbore to the original permeability Ke at the end of the invaded zone RS. The effects of the permeability ratio, the depth of invasion, the reservoir size, and the wellbore storage were investigated. Results of this study show that for this permeability distribution, the permeability ratio has a profound effect on the pressure behavior while the depth of invasion plays an insignificant role. It also showed that the use of the average permeability of the invaded zone in the steady state skin equation gives almost identical results of the additional pressure drop due to formation damage at large times as those obtained from the exact solution. An approximate solution can be used for relatively high invasion depths (Rsd ≥ 20 ) which shows that the additional pressure drop is independent of the invasion depth
A New Practical Way for Calculating the Amount of Gas Flared Based on PVs in South Pars Gas Development Projects of IRAN
Authors: Khazaei M. , Pakizehseresht M. 
Published: March 2009

Abstract
Flaring is used as an effective and safe method of hydrocarbon vapor disposal whenever excess pressures should be released to prevent equipment failure on major upset conditions, such as instrument malfunction, power failure, or plant fire. It is also desirable to provide safe receipt and disposal of combustible, toxic gases and vapors released from process equipment during normal operation and as well as emergencies. One of the main concerns is having a keen understanding the amount of flaring gas and precise location of relieved gas injected to flare header.
In most oil and gas refineries, PVs are the main sources of continuous flaring in normal operation; further more, this will also ensure a constant flow of sweeping gas in flaring header.In emergency cases BDV (Blow down Valve), PSV (Pressure Safety Valve) and TSV (Temperature Safety Valve) are another flaring resources which will not be considered here. In this study a new calculation procedure for released gas due to PV openings is proposed based on thorough investigations made in one of South Pars development projects in Iran. This computation uses the design information in PVs datasheet as well as actual plant data for opening percentage values have been utilized from plant DCS system and PIMS (Plant Integrated Management System). The main advantage of this method is reporting the exact location of gas conducted to flare header, flow rate, condition of gas temperature, pressure, molecular weight and composition. So this makes it possible plant personnel to find the flaring cause earlier and rectify the problem sooner.