bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimal Process for Design of Fracturing Treatments in a Naturally-Fractured Volcaniclastic Reservoir: A Case History in the Cupen Mahuida Field, Neuquen, Argentina
Authors: D'Huteau E. , Ceccarelli R. , Pereira M. 
Published: December 2007

Abstract
The declining reserves in conventional gas reservoirs imply that the oil and gas companies must consider the production of tight no-conventional gas reservoir.
The Cupén Mahuida Field is a naturally fractured reservoir composed of series of volcanic and volcaniclastic layers developed into a synrift stage at the Triassic in the Neuquén Basin. To obtain economical production all interesting layers had to be fractured. Therefore, we can assimilate that field to a tight gas, no-conventional reservoir.
Due to the huge difference in production between the different layers fractured in the existing wells, and due to the differences in behavior of the pressure during the treatments, it was decided to conduct a detailed analysis of each case. This included well construction, perforating strategy, geology, petrophysics, images log, minifracs and fracture treatments.
The results of the study showed two directions of work: First, necessity to modify the operations schedule; second, we needed to improve the definition of what are the layers candidates to stimulation. So operationally, we decided to change the casing size, the perforation scheme and we included as normal practice the use of proppant slugs to reduce the tortuosity effects we may see. The selection of candidate was improved by a better understanding of the formation thru an evaluation of outcrops that permitted to characterize the volcano clastic events and to correlate them with images, nuclear magnetic resonance logs and pressure measurements. With that information and the pressure response in the minifrac analysis we define the optimum size of treatment and the final proppant concentration.
An Experimentally Validated Wormhole Model for Self-Diverting and Conventional Acids in Carbonate Rocks under Radial Flow Conditions
Authors: Tardy Philippe M. J. , Lecerf Bruno , Christanti Yenny 
Published: December 2007

Abstract
Self-diverting acids are commonly used in matrix acidizing treatments of carbonate formations, not only to increase permeability by generating wormholes, as with conventional acids such as HCl, but also to self-divert into zones of lower injectivity, in the goal of optimizing zonal coverage. In this paper, a new model for wormhole propagation is proposed, which describes both stimulation and diversion processes.
A preliminary model is presented, which predicts wormhole propagation under radial-flow conditions for conventional acids. Then, a new set of parameters characterizing the reactive flow of self-diverting acids is developed, and the above model is extended to include self-diverting mechanisms. In particular, it is shown how the new parameters related to wormhole growth and those to diversion can be assessed from linear core-flood experiments and integrated into a new radial-flow model for field-scale prediction. Using this model, a new criterion is developed for diverter efficiency as a function of permeability contrast. Finally, the model is validated against radial flow experiments.
It is found that self-diverting acids are characterized by two new parameters which, when combined with the model for wormhole propagation, can be used to predict the performance of self-diverting acids, both in terms of wormhole penetration and in terms of zonal coverage. Some criteria are also developed to assess the diversion ability of acids.
Integrated Reservoir Management Enhances the Recovery in a Mature Field
Authors: Pérez L. E. , Gonzalez J. G. , Gómez V. , Lozano M. E. , Sarmiento L. E. , Vargas J. A. 
Published: December 2007

Abstract
In the current and future scenario of an increasing demand for hydrocarbons, many companies have oriented their efforts to maximize the recovery in mature fields. This paper presents the implementation and results of an integrated reservoir management strategy that allowed revitalizing a field, which was previously considered as a marginal and currently is one of the main assets of the company.
Yarigui-Cantagallo Field, Colombia, is a compartmentalized, varying-dip monocline, with three main tertiary reservoirs. The field was discovered in the 1940's and reached its production peak of 20,400 STB/day in 1962 after two aggressive drilling programs. A third drilling campaign in the 1980's had poor results and no additional wells were drilled. At 1999 production declined to 5,000 STB/day. In order to mitigate production decline, and maximize final recovery, integrated reservoir characterization including structural, stratigraphic, and petrophysical reinterpretation, geostatistic modeling, advanced production analysis, PVT and pressure reinterpretation, and reservoir simulation have been conducted.
An effective reservoir management has been implemented, including infill drilling, optimized well completion, hydraulic fracturing and production optimization. As a result, production levels had increased up to 13,000 STB/day and 40 MMSTB of reserves have been incorporated. Future implementation of a waterflooding project and additional infill program will incorporate 35 MMSTB of reserves.
Integrated Analysis for PCP Systems
Authors: Becerra Moreno Oscar , Mena Romero Maria Eugenia 
Published: December 2007

Abstract
One of the concerns that artificial lift engineers have to face when they are working with PCP systems is the lack of information about effective procedures for PCP diagnosis and optimization. Most of the information available is limited to explaining the importance of keeping the fluid level over the pump to avoid dry run. On the opposite side, there are some studies that explain the hydrodynamics of the pumps, and how some variables, like intake void fraction and fluid viscosity affect the pump performance.
However, there is no information available that may help field engineers understand the relationship between operational conditions and internal performance of the pump to know how each condition in the well could affect the pump, and how to determine and understand which condition is best for the system.
This paper introduces a new procedure to be used for understanding PCP's wells performance and therefore determine the best condition for system operation. Based on a set of simple mathematical models and patterns recognition techniques, this procedure is a useful tool to reduce the timing to analyze PCP systems and to automatically determine the best operational conditions in terms of production and performance.
Design and Surveillance of Development Projects through Specific Software Tools: Importance of Data Management in Mature and Complex Fields in the Golfo San Jorge Basin, Argentina
Authors: Mazzola Ricardo , Cano Frers Isabel , Baldassa Dario R. , Valle Jorge , Lacivita Alejandro , Ponce Carlos A. , Viola Alfredo F. , Laffitte Miguel A. 
Published: December 2007

Proposal
Cerro Dragon is a mature Area located in the Argentine Republic, 90 km to the West of Comodoro Rivadavia and 1,900 km to the South of Buenos Aires, with a surface of 3,480 km2 and with 3,738 perforated wells.
Since its discovery in1958, and after a long history of production, a change of strategy on 1999 resulted in an important increase in Production and Reserves
Decision making at every level, such as people health, environment care, and strategic, organizational, structural, operative and technological planning, was key for the rebirth of this field.
The work is centered in how we handle the information, the entailment of the data bases and the use of systems we have built to contribute to maintain the production growth of the Cerro Dragón Asset.
Based on the field complexity we recognized that it was necessary to implement new tools that would allow us to make production and investments prognoses, integrating information from different sources, as well as to detect improvement opportunities.
The selected software tools allowed us to perform simulations and dynamically survey the projects. The information used came from geological, geophysical, physical production, interventions, measurements, and automation databases, among others. Some of them were developed during the 2 initial years (1999 – 2000).
The selected software tools additionally let us integrate the projects into the Long Term Plan, and Budget, taking advantage of the virtuous Circle of Plan-Do-Control-Learn.
A project simulation is solved in a period substantially shorter than the one it demands a conventional simulator, which is of great advantage at the time of analyzing different scenarios in an area where the structural complexity and the meager petrophysical information are important barriers at the time of making a study.
The control and daily pursuit of the Projects through these systems have favored substantially the fast decision making, the correct lease of resources and a better operative answer.
To complete the description of our Optimization options other tools and practices are described.
Pressure Evidence of Communication through a Canyon: Sedimentary, Structural, and Reservoir Management Aspects, Campos Basin, Brazil
Authors: Gangá Adriana O. , Braga Mário Sérgio S. , Silva Edilon R. , Bragança Glaucia H. , Maciel Walter B. , D'Oliveira Manoel M.S. 
Published: December 2007

Abstract
Caratinga giant oil field is located in the central part of Campos Basin, Southeast of Brazil, in water depths around 1,000 meters. The total reserve is around 290 MM boe in these turbidite sandstones, 78% of which are within the lower Oligocene Reservoir (CRT100) and 22% are within Oligocene/Miocene and Eocene/Paleocene reservoirs. The CRT100 is a turbidite submarine fan of maximum thickness of 40 m, that was further cut by a NW-SE, Lower Oligocene submarine canyon, that have segmented the reservoir in two blocks: North Block and South Block. This canyon was further filled by the Oligocene MRL600/700 and the Oligocene/Miocene MRL330 sandstones. These canyon-filling sandstones constitute the Central Block. The development strategy for this field included a Pilot Phase in which three producer wells, one in each block, produced to a FPSO. The history match of this production data did not consider connectivity between the North and South Blocks of the CRT100 reservoir; although, seismic data have suggested possible reservoirs connection through the Central Block. Despite these features were represented in the 3D reservoir modeling, the transmissibility multipliers used kept these connections closed. The definitive production system, with 12 producers and 8 injection wells, started in February of 2005. The extensive use of pressure down hole gauges and a dedicated reservoir team allowed the observation of very important new information about the reservoir hydraulic behavior. Among several other issues that have arisen, a good communication across the Canyon was confirmed, connecting the North and South Blocks. This effective hydraulic communication observed can be explained by the sand to sand juxtapositions between off-canyon and canyon-filling sandstones in some regions, whereas the low thickness reservoirs, associated to geological faults, can justify the fluid flow behavior in other regions. These issues have been considered in the flow simulation model. The results are showing an increment on the total recoverable oil, since some portions of the canyon sandstones that used to have a low recovery volume, are now being swept by the water flooding.
Experimental and Numerical Investigation of Proppant Placement in Hydraulic Fractures
Authors: Shokir Eissa M. El-M. , Al-Quraishi Abdulrahman A. 
Published: December 2007

Abstract
In hydraulic fracturing treatments, a fracture is initiated by rupturing the formation at high pressure by means of a fracturing fluid. Slurry, composed of propping material carrieby the fracturing fluid, is pumped into the induced fracture channel to prevent fracture closure when fluid pressure is released. Productivity improvement is mainly determined by the propped dimension of the fracture, which is controlled by proppant transport and proper proppant placement. Settling and convection (Density driven flow) are the controlling mechanisms of proppant placement. In this study, proppant transport and placement efficiency of four non-Newtonian fluids with controlled density differences was experimentally investigated and numerically simulated. Small glass model was used to simulate hydraulic fracture and parameters such as slurry volumetric injection rate, proppant concentration, and polymer type (rheological properties) were investigated.
It has been observed that small glass models easily and inexpensively simulated flow patterns in hydraulic fractures and the flow patterns observed are strikingly similar to those obtained by very large flow models used by previous investigators. Convection was observed to be significant flow mechanism even with small density contrast. As viscous to gravity ratio increases, due to increasing slurry injection rate or decreasing proppant concentration, convection settling decreases and proppant placement efficiency increases. Increasing non-Newtonian flow behaviour index (n) by using different types of polymers shows more gravity under-running and less proppant placement efficiency. Therefore, larger slurry volumes are needed to be injected in order to prop the entire fracture height. Experiments conducted were simulated and some of the simulated experiments were presented. The simulator quantitatively replicates the experimentally observed proppant placement and the match between the experimental and simulated results improves with the quality of fluids rheological data used in the simulation.
Using Openhole Horizontal Completion Technology to More Efficiently Complete Vertical Wells
Authors: Seale R. , Athans J. 
Published: December 2007

Abstract
Horizontal completion technology has progressed dramatically over the last six years, with the latest technical barriers being eclipsed with open hole technology. These completions have allowed multiple zones to be fractured while mechanically isolating each zone. The efficiencies and benefits of utilizing open hole horizontal completion technology has been well documented. From the enhanced production witnessed using open hole completion with mechanical isolation, to the operational benefits of multiple fracturing operations being pumped in one continuous operation equating to time savings, more efficient fracs, faster cleanup and less safety hazards. Conventional methods of cementing a liner in place, perforating, fracturing and repeating the process for the number of stages required can be very time consuming with the added expense of removing the frac plugs with coiled tubing (CT) after the operations have been completed.
The enabling technology that has been used successfully over the last six years for multi-stage fracturing in open hole horizontal wells has been successfully applied to vertical wells. This paper will detail the benefits of using open hole multi-stage fracturing technology with mechanical isolation in vertical wells. In some aspects this may seem a simple transition, however, there are many operational considerations that must be evaluated in many vertical applications that might otherwise not be factored into a horizontal completion. These operational considerations will be thoroughly outlined, including case histories where this technology has been successfully applied.
Optimizing Producing Wells with Solid Expandable Tubular Technology
Authors: Perez-Roca Eduardo 
Published: December 2007

Abstract
A practical field restoration and rejuvenation project requires an economically efficient and technically astute plan. Using existing infrastructure allows operators to build a sound value proposition by capitalizing on previous investments. Enabling technology, such as solid expandable tubulars, makes the proposition even more attractive by further minimizing project costs. Solid expandable tubulars provide a technology that offers variable solutions without sacrificing hole size or compromising budgets.
Solid expandable tubulars have built a legacy as a viable and practical workover technology, based on over 660 installations. As acceptance and use of expandable systems increases, so do the application venues where they can be used to facilitate well remediation. Expandable systems repair and/or reinforce existing casing while minimizing loss of hole size, which enables use of the same completion. The systems have also provided the impetus for operations that result in compelling returns on production enhancement projects for old and new wells and fields.
This paper will explain how solid expandable tubular systems are used to repair and remediate wells that developed casing integrity problems and wells that experienced flow-constrained problems. Case histories will be used to illustrate how the technology was used to mitigate production problems and retain or improve value. In addition, this paper will discuss the economic implications of using this revolutionary technology.
Fluid Distribution Model for Structurally Complex Reservoirs in El Carito-Mulata and Santa Bárbara Fields, Venezuela
Authors: Carpio G. , Rodríguez F. , Khan K. , Contreras A. , Campos L. , Idrogo C. , Labastidas E. 
Published: December 2007

Abstract
El Carito-Mulata and Santa Bárbara fields are located in Eastern Venezuela in the Maturín sub basin and cover almost 300 km2. The asymmetrical anticline of the reservoirs is the result of different tectonic regimes alternating compressive and extensive periods from the late Cretaceous to the Middle Miocene. The fields are producing 240,000 STB/D and their OOIP is estimated to be around 6.5 MMMSTB. The variation of the vertical fluid distribution is predominant. There is a light oil (condensate) at the top of the structure, black oil at the base and free water at different levels in the reservoirs. This vertical fluid distribution is not well represented in the dynamic simulation model, which increases the uncertainty on any prediction or elaboration of the production plan.
The main objectives of this study are the determination of the original fluid contacts and the construction of a fluid model, which takes into account the free water presented in the reservoirs. This model can also define the vertical and lateral extension of the oil fields, indispensable for the reserves estimation.
The integration of the different kinds of static and dynamic information of 149 wells was necessary in order to obtain a well-supported fluid distribution model.
The analysis of the large number of data allowed defining the geometry of the Tar mat (asphaltene content &gt; 20%), which is folded/faulted according to the structure and considered as a sealed layer in reservoir conditions, with thicknesses ranging between 300 and 500 feet. The irregular Tar mat surface limits the reservoirs and controls the free water levels in the fields. This new fluid distribution model was included at the numerical simulation model matching all the wells information about water or type of oil that has been produced or tested.
Quantitative Mechanism for Permeability Reduction by Small Water Saturation in Tight Gas Sandstones
Authors: Motealleh Siyavash , Bryant Steven L. 
Published: December 2007

Abstract
In tight gas sandstone the productivity of a well is sometimes quite different from that of a nearby well. Several mechanisms for this observation have been advanced. Of interest in this paper is the possibility that a small change in water saturation can change the gas phase permeability significantly in rocks with small porosity and very small permeability.
We quantify the effect of small saturations of the wetting phase on nonwetting phase relative permeability by modeling the geometry of the wetting phase. We also show how a porosity-reducing process relevant in tight gas sandstones magnifies this effect. The basis for these observations is a model of the grain-scale geometry of low-porosity sandstones. The model is built from a dense random packing of spheres modified geometrically to simulate quartz overgrowth cementation. To compute phase geometry and permeability we use a physically representative network model extracted from the model rock. At small saturations (at or near the drainage endpoint) the wetting phase exists largely in the form of pendular rings held at grain contacts. Pore throats correspond to the constriction between groups of three grains, each pair of which can be in contact. Thus the existence of these pendular rings decreases the void area available for flowing non-wetting phase. Because the hydraulic conductance of the throat varies with the square of the void area, the effect on permeability is disproportionate to the volume occupied by the rings.
Convention holds that connate water has little effect on oil or gas permeability because it occupies the smaller pores. Comparing predictions for unconsolidated model rocks with those for cemented model rocks allows one to reconcile this view with the sensitivity reported in the field and the laboratory.
Stimulation of Bypassed Pay Zones in Existing Wellbores
Authors: Moreno J. W. , Engler T. W. 
Published: December 2007

Abstract
A significant portion of the U.S. gas resources is located in low-permeability, bypassed pay zones, within multilayered sandstone-shale sequences. Acquiring these resources leads to operational and design difficulties in stimulation, particularly if the target zone is bounded above and below by existing producing zones. The objective of this work was to evaluate the impact of adjacent, existing producing zones on the stimulation design and hence production performance of the bypassed payzone.
To investigate this problem, a 3D planar, hydraulic fracture propagation model was constructed and superimposed on a 3D flow model. The physical model was comprised of three layers, the top and bottom representing previously stimulated and producing layers, and the middle layer the target or bypassed layer. The impact of lithology, fracture length and total stress variations over time on the fracture conductivity, fracture efficiency and average reservoir pressure were investigated.
Evidence of pressure depletion of the target layer was observed due to production of the upper and lower layers. The degree of depletion is dependent on the fracture length and lithology of all of the layers. That is, the ability to propagate a fracture in the target layer was a strong function of the shale content and to a lesser extent, on the hydraulic fracture length of the bounding layers. Increased shale content in the target as well as the bounding layers resulted in a decrease in fracture conductivity of the target layer. However, an increase in fracture length did not necessarily result in a decrease in fracture conductivity of the target layer.
The study includes examples of stimulating the Menefee formation in the San Juan basin.