bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Channel Fracturing in the Vaca Muerta Shale Formation
Authors: Ejofodomi E. A. , Cavazzoli G. , Morris J. , Prioul R. 
Published: June 2014

Abstract
The channel hydraulic fracturing technique was recently introduced to the oil and gas industry as an alternative to the conventional hydraulic fracturing methodology. Channel fracturing involves the creation of a network of open channels or flow paths within the stimulated fracture volume, enabling the increased flow of hydrocarbons through the channels and into the wellbore. This paper investigates the applicability of this novel technique in the Vaca Muerta shale and presents a case history evaluating the potential production benefits of this methodology.
Starting with a calibrated geomechanical model, an index profile was created using the ratio between the young's modulus and closure stress to determine if channel fracturing is applicable in the Vaca Muerta. The technique is compared to conventional hydraulic fracturing case to identify the differences in the created fracture properties. Based on the created channel fracturing index profile, the gross Vaca Muerta shale interval was divided into three intervals (lower, middle, and upper) and the process was repeated across each section to determine the incremental production impact across interval.
The result of this study shows that the channel fracturing technique is applicably in the Vaca Muerta shale and can potentially increase the production performance. The analysis also shows that this technique is more favorable primarily across the upper and middle Vaca Muerta intervals than the lower Vaca Muerta interval due to the high organics, low rock moduli, and high stress. Also, permeability degradation of the proppant pack does not negatively impact the overall conductivity in a Channel fracture system. Instead, loss of aperture reduces the conductivity by orders of magnitude.
Cyclic Water Injection in San Jorge Gulf Basin, Argentina
Authors: Perez Diego , Salicioni Federico , Ucan Sezai 
Published: June 2014

Abstract
Historical production operations in San Jorge Gulf Basin have shown that production loss of down time, due to operational problems or any strikes can be recovered in the same production period of the year without changing any operational conditions. The study of the physical processes involved in this phenomenon has motivated the investigation on cyclic water injection.
There is an extensive list of international references on cyclic water injection that can be traced back to the early 1960’ showing encouraging results on laboratory, simulation and field developments. Nevertheless, recently it has received renewed attention since for mature fields (i.e. after a long history of water injection) cyclic water injection now appears to be a very appealing option to conventional water flooding for it may lead to additional oil recovery at virtually zero additional cost.
Many thin fluvial sands saturated with viscous heavy oil, high area-thickness ratio, long history of secondary flooding, high water cut, and low recovery factor reservoirs were the selected candidates for cyclic water injection. The main reasons for the improved oil recovery were found to be that cyclic injection schemes increase the sweep efficiency through oil migration on the high saturation gradient around swept zones, reducing water channeling and fingering by means of stabilization of the displacement front. In addition, by keeping injected water in the reservoir, its energy is raised, oil production is increased and water cut is reduced.
In this paper, an alternative theoretical interpretation of the process is presented as well as simple simulation models of the heterogeneous and anisotropic sands distributions. Here we demonstrate that high oil incremental from cyclic injection is achieved even in total absence of capillary forces or heterogeneity. Besides, an exhaustive analysis of the main rock and fluid properties, cycle length and pressure conditions is performed.
The on-going cyclic water injection project in Las Mesetas field in San Jorge gulf basin western flank makes use of the maximum injection capacity by distributing the cyclic injection vertically by mandrels and per wells in a fashion that keeps stable the total water injection rate from the water plant and maximizes cyclic injection potential. Simulation history match in a small region of the project area is used to exemplify the different possible responses.
The field results proved the effectiveness of this process producing 11000 m3 of incremental oil in the firsts 18 months.
Porosity and Density Estimation from Seismic Inversion in Tight Gas Sandstones
Authors: Castillo F. , Aguilera R. , Lawton D. 
Published: June 2014

Abstract
A post stack seismic inversion has been applied to 2D and 3D seismic data in order to obtain a quantitative assessment of rock properties including density, compressional velocities and porosity in a tight gas sandstone. To achieve this objective, the study develops a new relationship between Acoustic Impedance (AI) and porosity.
This study focuses on a post stack seismic inversion through a band limit technique that involves three major steps: 1) Derive a low frequency velocity model using sonic logs, 2) Invert the seismic traces using a recursive inversion procedure giving as a result the middle frequency model band of the AI, and 3) Combine the previous models in order to obtain the full band limit inversion product.
The methodology is demonstrated using data from a tight gas reservoir formation chracterized with low porosity and permeability located at approximately 2, 000 meters (TVDSS) in the study area. From the model inversion, the acoustic impedance (AI) is compared with variations in porosity resulting in a reasonable correlation for the stratigraphic interval studied.
The methodology can probably be extended to other regions around the world, which possess tight gas formations with similar characteristics to the ones described in this work.
Applications of Formation Sigma While Drilling
Authors: Peternell A. , Hebert J. , Cao Minh C. , Fisher J. , Dupuis J. , Hobbs B. 
Published: June 2014

Abstract
Pulsed neutron generator (PNG) tools have been used historically in cased hole environments to provide formation sigma and carbon/oxygen (C/O) ratios to characterize reservoir depletion, gas/oil/water contacts, and waterflood sweep efficiency. However, one of the main challenges has always been planning the right acquisition time for the first sigma measurement. The implementation of a ruggedized PNG source in the multifunction logging-while-drilling (LWD) formation evaluation platform has allowed reservoir saturation determination using capture sigma measurements in open hole environments.
Comparisons of LWD sigma with wireline cased hole sigma has helped cross-validate the reliability and shortcomings of both measurements. On the other hand, and going beyond the historical application, new methodologies to apply sigma-while-drilling in formation evaluation have been developed. Through the integration of LWD resistivity and sigma measurements, which are collocated in the multifunction LWD platform, both formation water salinity and water saturationcan be simultaneously determined. New developments in Multi Depth of Investigation (MDOI) sigma help ensure that a noninvaded or true formation sigma value is determined. This paper demonstrates a unique application of sigma-while-drilling to determine water saturation where the water salinity is unknown.
The implementation of sigma-while-drilling technology has opened new frontiers that go beyond the common application as a baseline for monitoring logs. With the integration of collocated, pre-invasion measurements, it is possible to determine formation water salinity, key information in enhanced oil recovery (EOR) projects or exploration wells.
A Hybrid Approach to Closed-Loop Directional Drilling Control Using Rotary Steerable Systems
Authors: Matheus J. , Ignova M. , Hornblower P. 
Published: June 2014

Abstract
Traditionally, trajectory control in the drilling industry has been performed by experienced directional drillers, using drilling tools such as mud motors, these tools are just iron components, that limits the efficiency of the drilling process and rate of penetration (ROP). The introduction of Rotary Steerable Systems (RSS) enabled faster and efficient well bore delivery. This tested the limits of human operators to assimilate the MWD data, compare the actual well trajectory with the planned and take corrective actions to get back to the desire well plan.
A hybrid approach consisting of two levels is proposed to perform the trajectory control in the oil drilling industry using RSS. Level 1, attitude control, regulates inclination and azimuth downhole. Level 2, the outer loop, monitors the performance of the inner loop and controls the directional drilling commands issued to the tool to follow a predefined plan.
A next generation nonlinear trajectory control algorithm was developed and tested. This algorithm can hold inclination and azimuth downhole, run below mud motors, and perform an automatic turn, while holding inclination with the ability to control the gains while drilling ahead. This novel algorithm has been applied in various locations worldwide to control inclination and azimuth and keep true vertical depth (TVD) within tight tolerances. Conclusions and lessons learned from the analysis will aid future applications of the hybrid approach and the new algorithm.
Estimation for Representative Element Area of a Coquinas Analogue Using Statistical and Numerical Methods
Authors: Oliveira R. , Pepin A. H. , Carvalho M. S. 
Published: June 2014

Abstract
The Itapema formation consists fairly of a limestone reservoir section with coquinas (shell fragments) deposited under high salinity lacustrine conditions. The environment in which this deposits accumulated along with the diagenetic processes subsequently undertaken created reservoir rocks with high heterogeneity in several scales of investigation. The representative elementary length plays a major role to characterize such reservoirs. The present work describes a quantitative approach to determine the size of a representative elementary area (REA) using both numerical and statistical methods defined for a Coquinas analogue. Two effective properties are determined for the REA: Porosity and Permeability. The porosity is defined here as the visible porosity from a micro tomography slice and the permeability estimated from a virtual Darcy's experiment using a finite element implementation of Brinkman's equation. Brinkman's equation is deemed necessary to properly model the flow within the vugs and porous matrix. The REA is subject to periodic boundary conditions with a pressure gradient on each boundary face. The variance is estimated and used as a statistical instrument to guide the REA size and later compared to the results obtained from the porosity and permeability estimations. The laboratory routine core analysis (RCA) provides a bulk measurement for porosity and permeability of the whole Coquinas sample. The RCA is used to constraint the obtained results for the simulations and statistical estimation and delineate the asymptotic behavior.
Evaluation of Multiple Component Induction Logging in a Deltaic Environment: A case study
Authors: Aguilar C. , Govea H. , Jimenez J. , Salazar F. , Barboza J. 
Published: June 2014

Abstract
The Lower Eocene C Misoa Formation was deposited on a tidally-influenced low deltaic plain in the Bloque 8 Field, Lake Maracaibo Basin. As a result of the environment deposition usually sand layer thickness is below of tool's resolution, resulting in petrophysical properties being averaged across the shale and sand lamina. One of the measurements affected is resistivity hence is common to find low net pay reservoir. These low resistivity pays, characterized by electric anisotropy, are often overlooked or mistaken as water-bearing sands when conventional resistivity measurements are used for calculating their water saturation, especially when an oil based mud and traditional induction logs are acquired. More accurate and reliable petrophysical quantification is crucial for the economic decision to explore, develop, and produce these reservoirs. Klein et al. (1995) note that pronounced electrical anisotropy in porous sediments could be a good indicator of hydrocarbon pay.
The Multi-Component Induction (MCI) tool is comprised of three pairs of mutually orthogonal transmitter-receivers measuring all nine magnetic field components at 10 different frequencies. The main objective in this paper is to show how information of seven wells with MCI logs was incorporated into the petrophysical model in order to reduce uncertainties about water saturation calculation. Using tensor resistivity equations, true sandstone resistivity and the volume of laminar shale were computed. Water saturation estimation using traditional resistivity measurements in the reservoir have predicted initial water production; meanwhile MCI predicts that some intervals should not have it. All Production data available was used to determine which log derived saturation match with the real reservoir production behavior. Finally, we summarized how the lack of core and image logs information may cancel the benefits of having vertical resistivity, because N/G and porosity has a great impact in calculations.
New Work Flows for Well Interventions Using Production Data Center Solutions
Authors: Sosa J. , Bello Y. , Sahmkow R. , Marcano O. 
Published: June 2014

Abstract
To support the work of maintaining production levels in PEMEX E&P in Mexico, several workflows were created using a production integrated data center solutions. These workflows were applied to wells candidates to interventions (workovers, side track, stimulations, new locations, etc.) in the region.
Specific workflows were created depending of the problem, for example: positions in relations to the oil water contact and injection wells. These workflows consolidated and use all the different information analysis available in the production data center solutions, including: ▪ Plot: production and injection data, bottom hole pressure, wells interferences, salinity, percent mole of N2, etc.▪ Bubble and grid maps: production and injection cumulative, percent mole of N2 and water salinity.▪ Forecast: oil, water cut, GOR, WOR, etc.▪ Yortsos and Chan diagnostic plots.▪ Heterogeneity index.▪ Scatter plot: productions rate cumulative or any variable of interest.▪ Normalize plots.
Applying theses workflows, engineers can perform an accurate well analysis of exploitation conditions and its neighbor in order to technically support workovers and ensure the success of these. In fields where the methodology was applied success rate for well intervention was very good. Additionally, engineers can have a better way of planning rig schedule for their fields and optimize reservoir management times.
Strategy for the Development of Shale Gas in Peruvian Fields
Authors: Porlles J. W. 
Published: June 2014

Abstract
Currently, few shale gas fields have been discovered in Peru. These fields require technical and economic strategies for optimal development. The main aim of this paper is to show the location of sedimentary basins and stratigraphic columns of the main basins, where we can see the source rocks, which are likely to be candidates for exploration for shale gas and shale oil. On the basis of a comprehensive analysis, it will show different fields and their possible development techniques.
A Feasibility Study of Tar Sands Exploitation in Trinidad and Tobago
Authors: Ransome Godfrey 
Published: June 2014

Abstract
The continuous decline in Trinidad and Tobago's crude oil production has accelerated the drive to boost oil production from unconventional sources. One such source is a tar sands deposit with estimates of original volume in-place between 400 million and 2,000 million barrels of bitumen. To corroborate the volumetric estimates or determine the correct and acceptable volumes of bitumen resources, geostatistical analysis was performed. This was considered a critical first step towards assessing the feasibility of exploiting the tar sands.
Methods for converting bitumen from tar sands to synthetic crude oil (SCO) were analysed and a dry-retorting technique was selected to circumvent the environmental hazards associated with the traditional Clarke's hot-water process. Additionally, a socio-environmental survey was conducted with residents and workers in the area in order to estimate their mean perceived impacts of various aspects of bitumen extraction techniques and to have them weigh in on various possible proposed mitigation/remedial/compensation solutions.
The paper showed volumes of bitumen in place to average approximately 500 million barrels for a major tar sands reservoir. Capital costs, crude price, and environmental concerns impact significantly on the profitably of producing SCO from tar sands. The quantum of Government's take would be decisive in deciding investor participation since inclusion of royalty and corporate tax has resulted in a mere breakeven position for the base case scenario. Exploiting tar sands can be considered viable and could assist in boosting declining crude oil production in the country. Environmental mitigation and continuous prolonged remediation coupled with tax incentives would be necessary to quiet public outcry and attract investor interest.
Original Gas in Place Probabilistic Assessment Using Design of Experiments on Material Balance Models in the Dolphin Field
Authors: Guerrero A. , Gomez G. , Lerza A. , Dolan J. 
Published: June 2014

Abstract
Dolphin field is a mature gas field located in the East Coast Marine Area, offshore Trinidad. One of the methods to estimate gas initially in place (GIIP) of the field is material balance; however, this approach presents some particular challenges which include: sands are not well consolidated and exhibit very high rock compressibilities, communicating reservoir compartmentalization and wells are produced at very high rates. These three factors don't allow for a straight-forward understanding of the aquifer size, normally assessed with a deterministic Cole Plot analysis. As a result of these complexities, analysis demands a more in-depth understanding of the uncertainties of the reservoirs and their implications on fluid in place estimation to avoid bias and anchoring. This paper presents a case study of the workflow used in determining probabilistic material balance models for one sand in the Dolphin Field.
Initially, an uncertainty analysis was conducted to determine the appropriate ranges of petrophysical data and aquifer properties that were used as input information for the material balance models. Experimental Design was then successfully applied to generate probabilistic material balance models: Placket-Burman design of experiment was used to identify the key uncertainties in a linear model. Monte Carlo simulation was used with the resultant response surface equation to determine probabilistic volumes of the field.
This project successfully achieved a probabilistic GIIP range for a single method testing sand of the field, ultimately yielding a better understanding of the significant uncertainties and their implications. The resulting probabilistic material balance models also enable the use of an integrated asset model to generate fit for purpose forecasts and a provides a more rigorous quality checking method on reservoir simulation results.
This paper will discuss a simple workflow used in probabilistically determining GIIP for one producing horizon in Dolphin field. Given the high confidence results encountered on the single sand, this approach will be applied to all Dolphin sand horizons to provide higher confidence GIIP estimates for the entire portfolio.
Successful Polymer Gels Application in a Highly Channeled Peripheral Injection Well: Tello Field Pilot
Authors: Maya G. , Castro R. , Sandoval J. , Pachon Z. , Jimenez R. , Pinto K. , Diaz V. , Zapata J. , Perdomo L. , Muñoz S. 
Published: June 2014

Abstract
Tello Field is operated by ECOPETROL S.A. and located in the Upper Magdalena Valley Basin, Colombia. It began production in 1972 and reached a maximum primary rate of 11, 200 BOPD in 1980. A peripheral water injection process started in 1997, reaching a maximum secondary production of 15, 552 BOPD in 2000. From this date, water production has increased due to an unfavorable mobility ratio (M &gt; 3.5) and a high permeability contrast (Dykstra-Parson coefficient: 0.8 - 0.9). The current recovery factor is 22% and water cut is 92%.
This paper summarizes from the laboratory to the field evaluation of a successful polymer gel project for controlling water thief zones, implemented as a strategy to reduce the phenomenon of channeling identified between the injection well Te-49 and the producer well Te-46. The design includes laboratory test (fluid – fluid, fluid – rock and cinetic reaction) to determine the right polymer and the necessary polymer and crosslinker concentration to obtain consistency of the gel at the reservoir conditions.
Polymer gel injection began in October 2009, reaching 43, 400 bbl of solution injected (13% of channel volume) and being the largest Latinoamerican polymer gel treatment until now. Injection strategy considered a maximal polymer concentration of 7000 ppm and a fixed polymer/crosslinker ratio ranging from 40:1 to control maximum injection pressure. Field results showed an important increase in oil recoveries (oil production up to 300%) and a reduction in water cut (3%). Comparing these results to what is normal obtained with this technology this is one of the most efficient process until now, this is more relevant when taking into account the peripheral condition of the water injection.
This work led to design and implement processes for water injection channeling control to improve the efficiency of water injection into other areas of the Tello field and other Colombian fields.
Material Balance Analysis of Naturally or Artificially Fractured Shale Gas Reservoirs to Maximize Final Recovery
Authors: Duarte J. Cabrapán , Viñas E. Cáliz , Ciancaglini M. 
Published: June 2014

Abstract
Unconventional shale gas reservoirs are acquiring more relevance nowadays, so the industry should focus on the optimization and development of unconventional exploitation techniques. In order to produce shale gas, the reservoir needs to be naturally fractured or, otherwise, stimulated by artificial procedures.
The purpose of this study is to present an analytical tool based on the Material Balance Equation ignoring water influx (Aguilera 2008) and adapted for this kind of reservoirs, by doing a sensitivity analysis through the variation of ω, the original gas in place stored within the fracture system. Applying a plot of p/Z (pressure and deviation factor ratio) vs. Gp (Cumulative Gas Production), it can be determined when the matrix's contribution begins to manifest, and this point represents a critical moment since the fracture is closing and, consequently, the production's decay rate intensifies. By knowing the critical Gp, a relation can be made with the corresponding reservoir pressure and an estimation on the production of adsorbed gas by applying Langmuir Isotherm can be done as well. It is noteworthy that this method may be used both for natural and artificial fractures systems, considering that they behave likewise when the latter has a fracture system not propped correctly.
Therefore, to maximize final recovery and to avoid a premature closing of the fractures, the critical Gp and the adsorbed gas must be considered.
This work presents a new Material Balance Equation, which takes into account dual porosity system and desorption mechanisms to calculate OGIP. Considering the production rate, the critical time can be estimated to anticipate a proper moment for a re-stimulation.