bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phenomenological Correlation of Pressurization/Depressurization Hysteresis of Stress-Dependent Porosity and Permeability of Shale Reservoirs
Authors: Civan Faruk 
Published: October 2017

Abstract
This paper presents a theoretically rigorous correlation of the effect of poroelasticity on pressurization/depressurization hysteresis of stress-dependent porosity and permeability of shale reservoirs. Naturally fractured shale formations are characterized as a matrix-fracture system. The constituents of this model are individually described by their own stress-dependent properties which are then coupled to determine the overall stress-dependent response of the shale system. This model accounts for the deformation, transformation, deterioration, and collapse of the shale pore structure during pressurization and depressurization processes and their effect on the porosity and permeability of shale reservoirs. The comprehensive model developed in this study is then validated by means of the experimental data gathered by testing of samples from various shale and sandstone reservoirs. The phenomenological parameters of the shale and sandstone samples are determined for best match of the experimental data. The data analyzed in this study indicates that pressurization/depressurization hysteresis has a significant effect on the stress-dependent porosity and permeability of shale reservoirs. The model developed in this paper can describe the stress-dependent porosity and permeability of shale rock more accurately than the commonly used empirical correlations.
Detecting Poor Cement Bonding and Zonal Isolation Problems Using Magnetic Cement Slurries
Authors: Nair Sriramya D. , Patzek Tadeusz W. , van Oort Eric 
Published: October 2017

Abstract
There has been growing interest in the use of magnetorheological fluids to improve displacement efficiency of fluids (drilling fluids, spacer fluids, cement slurries) in the eccentric casing annuli. When magnetic particles are mixed with the cement slurry for improved displacement, they provide an excellent opportunity for sensing the presence and quality of cement in the annulus. This work focuses on using sophisticated 3D computational electromagnetics to simulate the use of a magnetic cement slurry for well cement monitoring. The main goal is to develop a new tool, which is capable of locating magnetic cement slurry that is placed behind a stainless steel casing. An electromagnetic coil was used to generate a magnetic field inside the borehole. It was found that when a current was passed through the electric coils, magnetic field lines passed through the stainless steel casing, the cement annulus and the rock formation. Three sensors were placed inside the cased borehole and the magnetic field strength variations were observed at these locations. Various factors that have a significant influence on zonal isolation were considered. These include, effect of debonding between casing and cement annulus, effect of changing annuli thickness, influence of a fracture in the rock formation, effect of changing magnetic permeability of cement and finally influence of annuli eccentricity. Based on the results shown in the paper along with the next generation of supersensitive magnetic sensors that are being developed, the magnetic approach appears to be a viable alternative for evaluating the quality of the cement annulus to ensure good zonal isolation.
Reaction Rate of a Novel In-Situ Generated HCl Acid and Calcite
Authors: Arslan Emre , Sokhanvarian Khatere , Nasr-El-Din Hisham A. , Shimek Nicole , Smith Kern 
Published: October 2017

Abstract
A new in-situ generated HCl acid was developed to overcome the fast reaction rate and high corrosion rates of 15 wt% regular HCl acidizing system. The objectives of this work are to: (1) examine the reaction rate of the new in-situ generated HCl with calcite at 100, 150, and 200℉, and (2) compare the reaction rate of 15 wt% regular HCl with the new in-situ generated HCl.
The rate of the reaction of 15 wt% HCl and the new in-situ generated HCl was measured using the rotating disk apparatus (RDA). Calcite disks were used with the specifications of 1.5 in. the diameter and 0.65 in. thickness. The effects of disk-rotational speed (200-1,200 rpm) and temperature (100-200℉) were investigated. Calcium concentrations were measured in the samples collected from the RDA, which were used to calculate the rate of dissolution. The disk surface after the tests was analyzed using Scanning-Electron-Microscope–Energy-Dispersive Spectroscopy (SEM-EDS).
Experimental results showed that the rate of dissolution at 100 and 150°F was controlled mainly by the rate of mass transfer of the acid to the surface. By increasing the temperature to 200℉, the overall rate of reaction for the in-situ generated HCl was mass transfer limited up to 800 rpm and surface limited above 800 rpm. Based on the dissolution rate results, the diffusion coefficient, the activation energy, and the reaction rate constant at 100, 150, and 200°F were determined for the new developed in-situ generated HCl and were compared to 15 wt% regular HCl.
This study will assist in developing a more cost-effective and efficient design of acid treatments through a slower reaction rate of the in-situ generated HCl. This new in-situ generated acid system reacts slower and more efficient compared to regular HCl in carbonate and sandstone reservoirs.
Challenges of Delivering Capital Projects in Fast Growing Indigenous Oil and Gas Company NOC: The SEPLAT Experience
Authors: Oladipo Adekola 
Published: October 2017

Abstract
The challenges facing indigenous oil and gas producing companies operating in the Niger-Delta are enormous especially during periods of supply glut with its resultant low crude oil prices. This paper identifies the key issues limiting the effectiveness of project delivery in indigenous oil and gas companies in the Niger-Delta and the attendant impact on the value to investment ratio. It then proffers practical and cost effective solutions that will mitigate against the erosive impact of these challenges.
The key issues limiting the effectiveness of project delivery in all the cases studied resulted in poor project delivery with significant project value erosion. Results showed that optimal value was not derived because of poor project phasing occasioned by a desire for an accelerated payout. In most cases the funding for such capital projects was sourced from financial institutions as loans with high interest rates. This urgency for a quick cash-out leads to poor Project Management practices and processes in most of the cases reviewed.
The critical success factor(s) of the projects were also evaluated using novel success screening criteria customized in-house for each project. Long term cost/Opex was also considered as one of the key factors. Some of the challenges experienced by indigenous national oil companies in capital project delivery as observed from this study are: variations due to improper scoping, poor project execution, poor stakeholder mapping and engagement, technical and technological limitations, poor cost management and poor concept selection and implementation resulting in high maintenance cost etc.
A new effective project delivery model was thus developed for all fast-growing indigenous oil and gas companies in the Niger-Delta and it has been proven from the studies to guarantee good cost savings (cost improvements of more than 10%) while ensuring that project delivery deadlines are met (reduction in project execution schedule by up to 15%). Other proven benefits of this model are: Improved Plant Availability and Reliability, Elimination of pre-mature failures, reduced HSE Risk, reduced OPEX, delivery of quality project and eliminating re-works, Improved Partner Relationship and Increase in Production
For effective capital project delivery and guarantee of return on investment, Proper scoping, planning, robust technical challenge of capital projects (benchmarking of such projects will create great value and increase the overall profitability), Implementation of change management, proper roles assignment (RACI), documentation of lesson learnt/dissemination of information to all the relevant stakeholders must be in place. A new project management life cycle was developed specially for fast growing oil and gas producing companies.
Well Collision Avoidance - Separation Rule
Authors: Sawaryn S.J. , Wilson H. , Bang J. , Nyrnes E. , Sentance A. , Poedjonoand B. , Lowdon R. , Mitchell I. , Codling J. , Clark P.J. , Allen W.T. 
Published: October 2017

Abstract
The well collision separation rule presented in this paper is a culmination of the work and consensus of industry experts from both operators and service companies in the SPE Wellbore Positioning Technical Section (WPTS). This is the second of two papers and complements the first paper SPE 184730 which described the collision avoidance management practices. These practices are fundamental in establishing the environment in which a minimum allowable separation distance (MASD) can be effectively applied. A standardised collision avoidance rule is recommended, complete with parameter values appropriate to the management of health, safety and environment (HSE) risk, and benchmarks for testing it. Together, these should help eliminate the disparate and occasionally contradictory methods in use today.
The consequences of an unplanned intersection with an existing well can range from financial loss to a catastrophic blow-out and loss of life. The process of well collision avoidance involves rules that determine the allowable separation and the management of the associated directional planning and surveying activities. The proposed separation rule is based on the pedal curve method and is expressed as a separation factor, a dimensionless number expressed as a ratio of an adjusted centre to centre distance between wells divided by a function of the relative positional uncertainty between the two. The recommended values for the rule's parameters are based on a comparison of various industry models and experience. The relationships between key concepts such as separation factor, MASD and allowable deviation from the plan (ADP) are discussed, together with their interpretation and application. The dependency on the error distributions of the survey instrument performance models used to establish the tolerance lines is also discussed.
The consequences of implementing a standardised separation rule across the industry are far reaching. It influences slot separations, trajectories, drilling practices, surveying programme and well shut-in. It is shown how the MASD can be related to a probability of crossing and being on the far side, or wrong side of an offset well. It is shown why this qualification is required for safe drilling practices to be preserved. Examples are presented to help the reader validate the calculations and software necessary to perform them. The limitations of the methods are explained and areas are highlighted for further work. The methods outlined here, taken together with SPE 184730, if implemented will improve efficiency in planning and executing wells and promote industry focus on the associated collision risks when drilling. The WPTS is also supporting the current development of the API Recommended Practices for Wellbore Positioning (RP78). Mathematical derivations or references are shown for all the calculations presented in the paper.
Methodology to Systematically Reduce Uncertainty Assimilating Quantitatively 4D Seismic and Well Data in a Probabilistic and Multi-Objective History Matching
Authors: Rosa Almeida Forlan La , Davolio Alessandra , Schiozer Denis José 
Published: October 2017

Abstract
History matching (HM) is a complex process that aims to increase the reliability of reservoir simulation models. HM is an inverse problem with multiple solutions that calls for a probabilistic approach. When observed data are integrated with sampling methods, uncertainty can be reduced by updating the probability density function (pdf) of the attributes. This work presents a practical methodology to systematically reduce uncertainties in a multi-objective probabilistic assisted history matching, integrating well and 4D seismic data (4DS) quantitatively. The pdf update goes through an iterative process. The pdf of the current iteration is combined with the pdf generated using the best-matched models to generate the posterior pdf. The multiple local objective functions (OF) are evaluated independently, allowing the identification of OFs that indicate the requirement of re-parameterization. This quantitative process was applied in two phases: (I) using only well data to constrain the models; (II) adding 4DS data. The methodology was successfully validated against a benchmark case of medium complexity, with the history-production data generated at fine scale (reference model). The proposed methodology reduced uncertainties for the majority of attributes, achieving the highest probable levels similar to those of the reference values. The identification of objective functions that restricts the match allowed improving of the parameterization employed, by locally adding probabilistic perturbations to the petrophysical realizations. The method efficiently achieved multiple matched simulation models, with all (87) local objective functions within the defined tolerance range. Each iteration increased the number of matched models, demonstrating good convergence. The uncertainties were reduced gradually, avoiding premature level elimination (minimizing convergence at an incorrect solution). In both phases, the matched simulation models presented similar production forecasts to the reference model. The 4D seismic data were included regionally with an acceptable increase in computation time. The quantitative incorporation of 4D seismic data generated models that forecasted production with less variability than models generated without 4DS data. This was expected as for this study, 4D seismic data provided perfect information.
New Wireless Acoustic Telemetry System Allows Real-Time Downhole Data Transmission through Regular Drillpipe
Authors: Hawthorn Andy , Aguilar Sergio 
Published: October 2017

Abstract
One of the key enablers for the huge advancements in oil field drilling has been the ability to access downhole data in real-time to facilitate decision making. It is hard to imagine wells being drilled now that do not have even a basic Measurement While Drilling (MWD) tool in the Bottom Hole Assembly (BHA). The huge advancements in geosteering and the development of highly deviated and horizontal drilling absolutely necessitate access to real-time downhole data.
However as wells have become more complex both onshore and offshore the actual amount of time spent on bottom drilling has significantly decreased as a percentage of total well construction activities. Some operators have seen that in the deepwater environment this may actually constitute less than 15% of total well time.(Blacklaw: SPE GCS Annual Drilling Symposium. April 2016). Casing, cementing and completion operations have not had the benefit of access to real-time downhole data. They have instead relied on surface measurements and associated modelling which has often been seen to deviate severely from what is actually happening downhole.
This paper will take a look at a new wireless acoustic telemetry system that has the ability to transmit right across the well construction operating envelope, and thus has the potential to give operators access to downhole data throughout all well construction operations. It is postulated that this access to data has the potential to inprove efficiency, limit non production time (NPT) and improve the safety of operations from spud through production.
Repeatable Steady-State Foam Experimental Data and Investigations of Foam Hysteresis in a Sand Pack
Authors: M'barki O. , Ma K. , Ren G. , Mateen K. , Bourdarot G. , Morel D. C. , Nguyen Q. P. 
Published: October 2017

Abstract
The repeatability of steady-state foam experiments in porous media had been a major concern due to either alterations in core petrophysical properties or the impact of trapped gas. Trapped gas is an important cause of history-dependent foam behavior known as foam hysteresis. The removal of trapped gas generated in a previous foam experiment can sometimes be difficult when one tries to restore the core for a subsequent experiment.
This paper presents systematic studies of steady-state foam behavior without hysteresis and foam transport with hysteresis. We developed a procedure to restore a sand-pack system after a foam flood, which ensured that every foam experiment started with the same condition of the sand pack saturated with 100% surfactant solution and ruled out the impact of surfactant adsorption or gas trapping. An experimental design composed of 24 steady-state foam core floods were carried out and the local pressure drops were measured and correlated with varying phase (gas and water) velocity and foam quality. Next, two groups of foam hysteresis experiments were conducted by varying either the foam quality or the total fluid velocity.
The results showed that the repeatability of the experimental data was excellent in the hysteresis-free experiments. In addition to the steady-state data obtained in traditional high- and low-quality flow regimes, we have also identified a transition to highly viscous foam where the pressure gradient increased significantly from the entrance to the exit of the sand pack at steady state. This transition has only been observed with relatively low foam qualities and high liquid velocities. Multiple pore volumes of injection before foam reached a steady state in most of the experiments were observed. Various possible reasons, such as the requirement of minimum pressure gradient and the homogeneity of the system, are discussed. In the subsequent study of foam hysteresis, the first group of experiments showed that the final steady states of foam apparent viscosity at fixed foam quality and total fluid rate were generally repeatable regardless of initial state (phase saturations) of the sand pack in the high-quality regime; however, the initial state had a significant impact on the transient process before reaching a steady state. In the second group of experiments, the results indicated that foam hysteresis had a significant influence on the final foam steady state.
To our knowledge, it is the first time that such reliable and systematic data base for steady-state foam behavior in porous media without hysteresis was provided. This comprehensive data set in combination with foam-hysteresis data could therefore be used for foam-model evaluation and improvement with high confidence.
Achieving Directional Control and Rathole Elimination While Under-Reaming Depleted Formations with a Rotary Steerable System
Authors: Greenwood Jeremy A 
Published: October 2017

Abstract
An oil and gas operator in the Gulf of Mexico planned to drill a deepwater well section in one run by concurrently drilling and enlarging a 12 1/4- to 14 1/2-in. hole while deviating from 60 to 30° inclination and crossing expected depleted formations. At section total depth (TD), the rathole below the under-reamer needed to be eliminated to help ensure successful cementing of the liner. A bottomhole assembly (BHA) was designed to allow achieving these objectives in one run, and the field results obtained with the system are described.
The first step in determining the best BHA design was to compile drilling experiences through the target formations and perform a comprehensive review of all pertinent offset well information. Weaker zones had been encountered in the 12 1/4- × 14 1/2-in. section, and an at-bit reamer (ABR) had to be included in the BHA to allow the liner to be set on bottom of the section, rather than leaving an 85- to 135-ft rathole. Because the ABR placement in the BHA is between the bit and the rotary steerable system (RSS) tool, it was important to ensure directional control could be maintained in the section and make certain no interference existed between the ABR and the wellbore that could compromise control. Stabilization and placement of the under-reamer were crucial also to ensure the necessary directional performance was obtained without overstressing the BHA components, and extensive modeling was performed to optimize the design. Thorough hydraulics and torque and drag modeling ensured the BHA design could drill the depleted zone without premature activation of either reamer.
The detailed modeling and analysis of offset performance resulted in successfully drilling the section and opening the rathole in one run. The BHA was steered to the final desired angle and reached the section TD without incident and at the desired rate of penetration (ROP). Once the section TD was reached, the ABR successfully opened the 12 1/4-in. rathole to the desired 14 in., allowing the liner to be set 3 ft from bottom. This type of operation would normally require a separate dedicated hole-opening run. Using the new design eliminated the additional trip and the time necessary to open the hole, which was estimated at 56 hours.
A BHA solution was developed through detailed modeling that allowed the operator to not only maintain the steerability needed to achieve directional requirements with an ABR between the bit and the RSS while drilling depleted formations but also to concurrently perform under-reaming.
Smart Lost Circulation Materials for Productive Zones
Authors: Mansour A. , Ezeakacha C. , Taleghani A. Dahi , Li G. , Salehi S. 
Published: October 2017

Abstract
Lost circulation occurs when mud or cement is lost to the formation while drilling. Lost circulation has been a huge problem and may cause heavy financial costs in the form of lost rig time and mud fluid and in severe cases, well blowout with serious environmental and safety consequences. Despite extensive advances in the last couple of decades, lost circulation materials used today still have disadvantages such as damaging production zones, failing to seal the fractures or just sealing the fractures without strengthening the well. Here, we propose a new class of smart expandable lost circulation material (LCM) to remotely control the expanding force and functionality of injected LCM. Our smart LCM is made out of thermoset shape memory polymers and becomes activated by formation natural heat as well as electromagnetic waves if needed, hence it can effectively seal fractures’ width without damaging production zone and strengthen the wellbore. The activation temperature of the LCMs can be adjusted based on the formation temperature. We conducted a series of experiments using a HPHT particle-plugging apparatus (PPA) to measure the sealing efficiency of the smart LCMs as a proof of concept. Various slot disc sizes were used to mimic different size fractures in the formation. The API RP 13 B-1&2 have been followed as standard test methods to evaluate fluid loss in water based muds.