bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analogous Reservoirs to Chicontepec, Alternatives of Exploitation for this Mexican Oil Field
Authors: Gachuz-Muro Heron , Sellami Hedi 
Published: June 2009

Abstract
The giant Chicontepec field contains oil from 18 to 45 °API in laminated sandstones of 0.1 to 10 mD at a depth of around 2500 meters (8202 ft). Original Oil in Place (OOIP) is estimated to be 140, 900 MMSTB. The complex geology (complicated structural and stratigraphic nature of the reservoirs), lack of reservoir information and lack of technology availability caused a gap between discovery and development. Throughout a period of several decades some exploration wells were drilled based on 2D seismic and log correlations of the reservoirs.
The exploitation of the Paleonchannel was postponed because most of the wells showed poor productivity. The reasons for the low recovery (around 3%) have never been thoroughly understood. Various hypotheses have been proposed to explain the deficient performance such as partial closing of the fractures with declining reservoir pressure (bubble-point pressure is near initial pressure), inadequate comprehension of the geological model, deficiency in the fracturing technology, oil-wetted or intermediate-wetted reservoirs, applicability of unconventional wells (horizontal wells, casing drilling technology), etc. Today, the Chicontepec Paleochannel is an intermediate stage.
Due to the experience of different fields with similar characteristics, this paper describes an analysis of alternatives that may be considered to resolve the problems of exploitation at the Chicontepec field. Advanced technologies, hydraulic fractures, artificial lift systems, all of them combined with secondary and enhanced oil recovery, may be feasible to sustain or increase production. A number of hurdles will have to be overcome. This field, the second most important oil field in Mexico, should take advantage of the experience learned from these analogous reservoirs.
Gas Injection IOR for Widely Varying Initial Compositions
Authors: Singh Kameshwar , Whitson Curtis H. 
Published: June 2009

Abstract
The paper presents the effect of initial reservoir fluid composition on oil recovery for reservoirs under gas injection. To analyze the effect of initial fluid composition, a series of fluid systems were selected based on isothermal gradient calculation from a North Sea field. The systems ranged from low-GOR oils to high-GOR gas condensates, with a continuous transition from gas to oil through a critical mixture.
In this compositional reservoir simulation study, a 3D dipping reservoir with dip angle of 3.8 degree was used. The reservoir layer permeabilities were varied based on Dykstra-Parsons model. Different average reservoir permeability was used to quantify the effect of gravity.
For oil reservoirs, the oil recovery of oil increases with increasing initial solution gas-oil ratio. The oil recovery increases gradually for low-GOR to moderate-GOR oil reservoirs. For moderate-GOR to near-critical oil, the oil recovery increases rapidly. The increase in oil recovery as the reservoir oil becomes more volatile is due to decrease in oil viscosity and the vaporization effects of the injection gas. For gas reservoirs, the condensate recovery increases rapidly from a near-critical gas towards near 100% condensate recovery for high-GOR systems. The oil recovery also depends on the permeability distribution. The oil recovery is higher in the case of high permeability at the bottom than high permeability at the top due to gravity segregation effect. The effect of gravity segregation on oil recovery is more pronounced in high permeability reservoirs. For lean gas condensate the oil recovery is almost independent on the permeability distribution.
The paper shows the variation of oil recovery with initial reservoir fluid composition for different permeability distributions, gas injection period, critical saturation, vertical to horizontal permeability ratio, level of pressure maintenance, and injection gas composition.
Pressure Transient Well Testing Encountered Complexities: A Case Study
Authors: Karami Pooyan , Hashemi Abolfazl 
Published: June 2009

Abstract
Pressure transient testing is one of the most useful reservoir description methods. It provides valuable information about the reservoir/well-bore characteristics (e.g., homogeneity, heterogeneities, phase segregation, stimulation effectiveness, interventions, etc.) and quantitative information about reservoir parameters (e.g., permeability, fracture length, average reservoir pressure, skin, wellbore storage, etc).
The study of pressure transient testing in one of the Iranian giant oilfields was initially undertaken to estimate important well and reservoir flow parameters and characterize heterogeneities in the Fn limestone formation; However, during the course of interpretation, numerous engineering complexities were encountered due to the nature of well behavior and reservoir conditions led to the masking of the actual reservoir response: 1) a high permeable reservoir with high degree of heterogeneities with high skin and high wellbore storage, 2) Partial penetration behavior due to asphaltene plugging on the sand-face/left fish in hole, 3) an obvious hump effect due to phase segregation inside the well 4)Pre and Post acid pressure transient response behaviors in a successful diversion acidizing operation 5)An interference response behavior due to a nearby well bore shut in.
The paper also presents how transient well testing in conjunction with dynamic pressure-production data have helped to clarify the boundary effect on a build up test; the modified build up secondary derivative based on the pseudo-steady state extrapolation of the preceding drawdown period shows a constant trend which recognized as close boundary effect.
The Effect of Oil and Gas Molecular Diffusion in Production of Fractured Reservoir During Gravity Drainage Mechanism by CO2 Injection
Authors: Kazemi A. , Jamialahmadi M. 
Published: June 2009

Abstract
During the primary production of fractured reservoir most of oil is produced from fractures and a lot of oil remains in matrix. Trapped oil in the matrix can be recovered by gas injection by activating gravity drainage mechanism. In addition there is a big impact of molecular diffusion of oil and gas in total oil recovery from fractured reservoir .The experimental work can by used to model this mechanism in combination of numerical simulator to investigate this phenomenon more accurately.
A fully compositional model has been applied to a numerical experiment in literature to investigate the drainage of CO2 from a core with artificial fractures and the effect of molecular diffusion included. The same study has been applied for a synthetic fractured reservoir model to investigate the effect of CO2 injection in oil recovery mechanism in the field scale.
In this work we found that at early stage we have oil swelling and gravity drainage followed by a slow extraction mechanism which recovers the intermediate and heavy components from the residual oil. The combined effect of diffusion and gravity suggests that application of the oil and gas diffusion coefficients is critical in any field scale simulation of a fractured reservoir and the correct diffusion coefficients should be applied.
A lot of oil reservoirs in the world are fractured and with primary recovery we can produce maximum 30 % of original oil in place therefore we need to have an accurate observation of secondary and tertiary oil recovery in these reservoirs. The understanding of oil recovery mechanism also is crucial for reservoir management especially when developing field management plans. A low miscibility-pressure requirement often is a significant advantage of CO2-miscible flooding. This process could have significant future application in areas with economical CO2 supplies from natural deposits or surface sources.
Pumping of Fluids Using Pressure Impulses
Authors: Pierre B. , Gudmundsson J. S. 
Published: June 2009

Abstract
Impulse pumping is a new method to pump fluids. The method is described briefly and then numerical simulations were carried out to illustrate the nature of impulse pumping. The simulations are based on the linear ideal wave equation and the numerical approach is based on a second-order Godunov scheme. The work illustrates how sinusoidal pressure waves are reflected at open and closed boundaries, representing open and closed non-return valves in impulse pumping. An impulse pumping example was presented for 40 m lifting of water. It was shown how the wellhead pressure used determines the lifting depth and flow rate achievable; the greater the wellhead pressure, the greater the lifting and rate. In impulse pumping the wellhead pressure is controlled by the cracking pressure of a non-return outlet valve. Fluid enters the production tubing through a non-return inlet valve downhole. The stroke length of a pressure wave generator determines the wellhead pressures achievable in impulse pumping. It was suggested that the water hammer equation can be used to estimate the flow rate in impulse pumping.
Predicting Water Influx From Common Shared Aquifers
Authors: Shimada Munenori , Yildiz Turhan 
Published: June 2009

Abstract
In this paper, we present 3-dimensional analytical models to forecast water influx from a common shared aquifer to several producing reservoirs. We consider finite aquifers and an arbitrary number and distribution of multiple reservoirs. The new analytical models have been verified by comparing them against the existing analytical models for the special case of symmetrical distribution of multiple identical reservoirs. The computation of the equations representing the analytical models is straightforward.
The new analytical models proposed in this study may be used for aquifer representation in reservoir simulators and material balance based reserve estimate studies. Using the analytical models, we show a sample calculation for irregularlyshaped reservoir on an aquifer.
Low Dosage, High Efficiency and Environment Friendly Inhibitors: A New Horizon in Gas Hydrates Mitigation in Production Systems
Authors: Kannan Krupa , Punase Aarti 
Published: June 2009

Abstract
Presently, gas hydrates formation pose problems, causing flow restrictions, in gas and oil industry including drilling operations (particularly in deep water), production process, well workovers where gas and water come into contact at equilibrium conditions. Traditional hydrate control methods of insulation and/or thermodynamic or chemical inhibition may not provide the desired level of hydrate protection at an economic price. Low-Dosage Hydrate Inhibitors (LDHIs) are a proven technology to control hydrates in numerous applications and are instrumental in reducing the total cost of operations. Low dosage Inhibitors are either kinetic, thermodynamic inhibitors or anti- aglomerants, which either prevent hydrate formation or remove the hydrates that are already formed respectively.
Therefore, this paper focuses on introduction to such low dosage inhibitor which can perform all the functions like prevention of formation of hydrate nuclei (like kinetic or thermodynamic inhibitors) and dispersing the already formed ones in flowlines (like anti- agglomerants). This paper proposes the use of Cationic polymers like cationic starch (from a high amylose carbohydrate source) in low concentration with addition of Polyethylene Oxide (PEO) as a new Gas Hydrates inhibitor.
The polymer with PEO, dissolved in water, can be introduced in petroleum fluid using mechanical equipment or utilized in treating fluid prior to substantial formation of the hydrates. As observed from an experimental analysis, these positively charged polymers interfere with nucleation of hydrates, increase induction time of gas hydrate nucleation, suppress memory effect, and act as antifreeze and thereby controlling hydrates.
With reference to these polymers, their abundant availability, easy application techniques and simple cationization procedure all contribute to its inexpensive and environment friendly usage as gas hydrate inhibitor. This paper provides systematic approach and relevant theoretical explanation for the proposed technique.
Mapping Karst Diagenetic Networks in Carbonate Reservoir Using Seismic Indicators and Well Data
Authors: Hamid A. , Sadeghzadeh F. 
Published: June 2009

Abstract
The diagenetic processes play the most important role on the creation and distribution of the reservoir characteristics. Karstification, by inducing secondary porosity through dissolution and therefore enhancing the porosity of the sedimentary facies, is a distinguished diagenetic process in carbonate reservoir's pore network formation.
The Fahliyan formation's structure is a symmetrical anticline elongated in N-S direction and was developed in a ramp type carbonate platform. The reservoir consists of three separate stacked-up pay zones, and the main production was from the middle and lower zones. Karstification was developed in Fahliyan and created the following two main dissolution events: –Early diagenetic dissolution process created secondary pores, as intercrystaline/ microporosity, molds and vugs (10 μm – 1mm. Size).–Paleokarst event generated secondary pores, as molds, large vugs (up to 2 cm. in size), solution enlarged fractures and solution pipes.
So far, the field was modeled as a layered carbonate reservoir with laterally homogeneous properties. Therefore an integrated seismic stratigraphic-sedimentological study is performed using 3D seismic indicators, log and core data to define a conceptual diagenetic model at the field scale for imaging the karst networks and characterizing their effective properties. The study determines a uniformly distributed early dissolution event without particular geometry or preferential orientation for the top zone and a North-South oriented elliptical porous zone around the structure for the middle and lower zone, which follows the geometry of a freshwater lens and is a result of karstification process. The integration of the seismic stratigraphic interpretation with well data and the results of the seismic inversion, led to the definition of reservoir quality maps for the reservoir layers. Karst network geometries were subsequently incorporated into a deterministic reservoir model and facies properties tested against 8 years of production history in an iterative dynamic simulation workflow.
Capillary Trapping Capacity of Rocks and Sandpacks
Authors: iglauer Stefan , Wülling Wolfgang , Pentland Christopher H , Al Mansoori Saleh K , Blunt Martin J 
Published: June 2009

Abstract
We quantify the influence of the initial non-wetting phase saturation and porosity on the residual non-wetting phase saturation based on data in the literature and our own experimental results from sandpacks and consolidated rocks. The principal application of this work is for carbon capture and storage (CCS) where capillary trapping is a rapid and effective way to render the injected CO2 immobile, guaranteeing safe storage.
We introduce the concept of capillary trapping capacity (Ctrap) which is the product of residual saturation and porosity that represents the fraction of the rock volume that can be occupied by a trapped non-wetting phase. We propose empirical fits to the data to correlate trapping capacity and residual saturation to porosity and initial saturation. We show that trapping capacity reaches a maximum of approximately 7% for rock porosities of 20%, which suggests an optimal porosity for CO2 storage.
Revitalising a Medium Viscous Oil Field by Polymer Injection, Pirawarth Field, Austria
Authors: Poellitzer Stefan , Florian Thomas , Clemens Torsten 
Published: June 2009

Abstract
The Pirawarth Field, located in Austria, has been considered for polymer flooding. The reasons were the good permeabilities, medium viscosity of the oil (50 cP), low reservoir temperature (30 °C) and injection of low salinity water, resulting in low polymer concentration requirements.
Production from this field started in 1964. Until 2008, the recovery factor of the field reached 26 %. The reason for the low recovery factor is the unfavourable mobility ratio between the viscous oil and water.
In addition to conventional history matching, produced water chloride concentration data was implemented as matching parameter. The chloride concentration match revealed that the geological structure of the field was not well represented, although the water cut increase could be matched. This lead to delayed simulated breakthrough of the low salinity injected water. Improving the geological model enabled an improved match of the injected water breakthrough.
Laboratory experiments confirmed high efficiency of polymers in increasing water viscosity for the Pirawarth conditions. A core flood experiment was conducted and showed that adsorption is limited, the water relative permeability will be reduced by polymer injection and that the displacement with polymer after water flooding results in incremental recovery of more than 20 % of oil in place.
The core flood experiment was simulated and the parameters derived from the core flood experiment were used in the dynamic model of the field. The results of the simulation are very promising, indicating an increase in oil recovery in the pilot area of 5 %. It is planned to perform the pilot in 2010.
Oil Recovery From a Tight Fractured Basement Field
Authors: De Kok J. , Neff P. , Clemens T. 
Published: June 2009

Abstract
A tight naturally fractured basement reservoir in the Middle East contains an oil column of at least 2950 ft. The reservoir fluid consists of light oil with viscosities ranging from 0.2 to 0.4 cP and is saturated at the top of the reservoir. The oil is produced through fracture corridors with an effective permeability of approximately 0.1 md. The background fractures have an effective permeability of less than 0.001 md. The average porosity of the field is 1.1%. This paper presents results and setup of a multi-disciplinary study with the aim of optimizing production of this tight reservoir.
Due to the high permeability contrast, a dual-permeability approach has been selected. Fracture characterization was based on outcrop studies, core data, borehole images, production logging results and conventional log interpretation. A discrete fracture network (DFN) was created incorporating all available data and assuming fractal behavior of fault and corridor distributions. The DFN was scaled up for simulation and several feedback loops were performed for dynamic calibration.
The resulting dual-permeability simulation model was used to investigate development strategies. Compositional grading was implemented to correctly describe the fluid properties within the high relief structure. Due to its low permeability, gas/oil segregation caused by gravity hardly plays a role in the background fracture network during depletion. Additionally, because of the low mobility contrast, gas saturation can build up to values exceeding 25%, even whilst assuming straight line relative permeability curves and zero critical gas saturation.
Simulation shows that a recovery of more than 10% is expected for depletion in this tight reservoir, which is exceptionally high for solution gas drive. Gas injection can yield additional recovery, but with larger uncertainties.
A New Skin Factor Formulation for Flow Around Horizontal Wells Including Anisotropy and Partial Penetration
Authors: Ghahri Panteha , Jamiolahmady Mahmoud , Sohrabi Mehran 
Published: June 2009

Abstract
Modelling flow around horizontal wells (HWs) is a complex and challenging task due to the three-dimensional (3D) nature of the flow including the permeability anisotropy. This work is aimed to provide a reliable tool for prediction of the well performance of HWs. The steady state Dracy flow of a single-phase incompressible fluid in a HW was simulated by developing a 3D single HW mathematical model using Comsol multi-physics mathematical package which is based on finite-element methods. In house simulator is validated and verified when comparing its results with the corresponding values obtained from ECLIPSE commercial simulator, and a number of semi-analytical models widely used in the petroleum industry, all for the same prevailing conditions. These semi-analytical equations have been obtained by simplifying the 3D system to two 2D problems. We demonstrate that this assumption is only appropriate if the thickness of reservoir model is small compared to the length of HW. Our results also indicate that these equations may not predict the well performance of HW correctly specially in low permeability anisotropy values. Based on the results of in house simulator, correlation has been developed for calculation of mechanical skin using the efficient statistical Response Surface Method. This skin factor is employed in an open-hole vertical well productivity equation giving the same flow rate as that of the HW. The results of the proposed formulation have been tested against new data points, which have not been used in its development confirming the integrity of the approach. Moreover, a comprehensive sensitivity study on the impact of pertinent parameters (i.e. HW radius, HW length, reservoir dimensions, anisotropy and partial penetration) on the performance of a HW has been conducted with some important practical findings.
Interventions with Reliable Execution in Hostile Environments
Authors: Schwanitz Brian , Henriques Kristine 
Published: June 2009

Abstract
A light weight intervention technique utilizing electric wireline has emerged as an alternative to existing well intervention methods. Tractor technology enables high speed, low HSE impact and a high degree of precision in production enhancing interventions in onshore and offshore wells. Wireline tractor technology eliminates the limitation on traditional wireline by extending the reach of the wireline into a high angle or horizontal part of the well bore, enabling access to the entire length of the well.
Interventions in challenging conditions such as subsea, deepwater, extended reach, high-yield, heavy oil and deepwater are also enabled whether the hole angles are highly deviated or not. For instance, where slick line or coiled tubing (CT) operations below 20,000 ft can be risky and costly, tractor technology offers a time and cost-efficient alternative for valve manipulation, sand clean out and scale milling. Furthermore, interventions have been performed in high temperature wells (388°F), high pressure (&gt;20,000 psi), ERD wells (&gt;30K ft) and high deviations (130°) wells.
Wireline tractor services can be mobilized in a matter of hours and only require a crew of from two to four people, depending on the operation. Transportation can be done in a helicopter to avoid the cost and time of mobilizing a full CT spread such as when cleaning and milling operations are performed without surface fluid handling logistics. Further, lightweight interventions with tractor technology combined with low surface impact left on the environment, allows mobilizations in eco-sensitive regions where heavy methods are not permitted due to the irreversible environmental damage that would be caused.
This paper will present case studies where the HSE impact was significantly reduced by employing lightweight intervention techniques through tractor related mechanical services. One case will be a recent operation of milling barium sulfate scale on electric wireline and removing the cuttings in the same run in the hole. The second case will be milling out a cast iron bridge plug on electric wireline and the third will highlight the world's first wireline tractor intervention from a subsea intervention ship, which provided a much lighter solution for the operator.