bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deepwater Reservoir Characterisation Using Tidal Signal Extracted from Permanent Downhole Pressure Gauge
Authors: Wu Xingru , Ling Kegang , Liu Dexin 
Published: March 2015

Abstract
Permanent Downhole Gauge (DHG) technology has been widely used in deep water reservoir development in the last decade and is playing an increasingly significant role in real time reservoir/well surveillance and reservoir management. Tidal signal extracted from the highly accurate and precise device can be used for reservoir characterization such as monitoring the changes of saturations and estimating rock pore compressibility. Most previous works treated tidal signal as pressure "noise" and little has been discussed on how to utilize the tidal information in reservoir characterization.
This paper will address how to use Fast Fourier Transform (FFT) to extract the tidal signal and the theory and method to process the signal for reservoir characterization purposes. In addition, several examples from some deep water fields will be discussed to illustrate how to use tidal information to estimate pore compressibility, monitor dynamic fluid saturation change, and detect the presence of secondary gas cap. This paper will show that FFT is a fast and reliable method to process the DHG pressure data for tidal signal which can be used for reservoir characterization in multiple dimensions. Furthermore, the results (pore compressibility and saturation) obtained from the tidal signal are very unique because they cannot obtained in laboratory, simulation, or direct measurements because of the scale impacted by tides.
Strategies of Land Internal Multiple Elimination Based on Inverse Scattering Series
Authors: Kelamis Panos G. , Luo Yi , Weglein Arthur B. 
Published: March 2015

Abstract
In spite of a plethora of novel innovative algorithms for multiple identification and elimination, the fact is that their applicability and success is in most cases questionable and limited to marine environments especially deep waters. In land seismic datasets however, a clear understanding of internal multiples and their generation is not readily available and thus efforts to attenuate them become cumbersome and quite often ineffective. Particularly in desert terrains with a complex near surface and low-relief structures, surface multiples are rare. In most cases, we are dealing with so called "near surface related multiples". These are basically internal multiples generated within the complex structure of the near surface. They exhibit little moveout discrimination with respect to primary reflections and thus cannot be removed with conventional technologies commonly based on Radon transforms. Their proper estimation and subsequent elimination requires a rigorous approach firmly rooted to wave equation concepts.
In this paper we employ theoretical principles of Inverse Scattering Series (ISS) and develop distinct, cost-effective, practical methodologies for internal multiple elimination applicable for land and shallow water seismic data. These fully-automated, data-driven algorithms require no picking of events and identification of multiple generators, assume no subsurface velocity information and can be applied pre and/or post-stack. They can accommodate the broadest set of internal multiples of all orders and can be extended to multi-dimensional earth models. Thus, multiples are surgically removed by predicting their amplitudes and phases and do not harm primary reflections, even if they are proximal and overlapping. A series of realistic synthetics and field land datasets from the Arabian Peninsula are used in order to demonstrate the effectiveness of ISS-based algorithms towards the attenuation of internal multiples.
Effects of Deviated Wellbore Stresses on Compressional Headwaves and Modal Dispersions
Authors: Sinha Bikash K. , Lei Ting 
Published: March 2015

Abstract
A new 3D finite-difference time domain formulation of equations of motion for elastic waves in prestressed formations has been used to calculate synthetic waveforms at an array of receivers in a liquid-filled deviated borehole. These equations describe the influence of borehole hydrostatic pressure as well as triaxial formation stresses on elastic waves produced by either a monopole or dipole transmitter placed on the borehole axis. The synthetic waveforms are processed by a slowness-time coherence algorithm and modified matrix pencil algorithms for isolating both non-dispersive and dispersive arrivals in the wavetrain. Computational results for the formation compressional, fast-shear, and slow-shear slownesses obtained from synthetic waveforms in a wellbore with deviations of 0o, 30o, and 60o from the vertical are consistent with the plane wave velocities in homogeneously stressed rock in the far-field subject to the rotated stresses referred to the borehole measurement axes. Compressional slowness changes are primarily affected by changes in the stress along the propagation direction. In contrast, shear slowness changes are equally affected by stress changes either in the propagation or radial polarization direction. Crossing dipole dispersions are observed for all deviations and the magnitude of shear slowness anisotropy is proportional the difference of principal stresses in the borehole cross-sectional plane. A deviated wellbore with the least amount of difference between the principal stresses in the cross-sectional plane is likely to be the most stable trajectory and is characterized by the least amount of cross-dipole shear slowness anisotropy.
Maximising Productivity of Standalone Screen Completions in Complex Multi-Lateral Wells
Authors: Nettleship Gary , Palmer Anthony , Eshtewi Abdullah 
Published: March 2015

Abstract
The Vincent project is a heavy offshore oil field developed by subsea multilateral wells with sand control. This paper will provide an insight into how completion practices were developed to maximize well productivity and how they were balanced against risks for constructing multilateral (ML) junctions.
The fluids used for drilling and cleaning up open-hole laterals can have a significant impact on well productivity in standalone screen applications, especially with respect to sand screen plugging. This paper details the development of open-hole fluid selection and clean up practices for completing long 2000m+ horizontal laterals with standalone screens. The Vincent wells are more complex due to drilling tri-lateral wells that include two TAML level 5 ML junctions requiring open-hole connections. The paper identifies the key risks for installing the ML junctions in a weak formation including risks imposed from clean up practices.
The paper reviews the lessons learned during execution, how the ML junction installation risks were mitigated and how the Vincent wells were delivered with a well performance meeting expectation.
New Generation of Aluminum Drill Pipes Enhanced the ERD Performances in to the Huizhou Field - South China Sea
Authors: Scaruffi W. , Cristofanelli E. , Yu S. , Trocchia A. , Molaschi C. , Merlo A. 
Published: March 2015

Abstract
This paper is to present the results of a important effort and continuous performances improvement into the ERD challenging drilling activity. CACT-OG is the operator of Huizhou HZ 25-4 oilfield in South China Sea, the discovery made in 2005 consisting in a multiple oil bearing The HZ 25-4 field is pertinent to the PSC 16/19, central area of Pearl River mouth basin, and it is located 6 km southwest from the already operating HZ 19–2 platform, in a water depth of 102 meters. A total of 7 wells have been drilled so far, from HZ 19–2 platform in three different drilling campaigns. After the first three wells campaign, a number of technical challenges have been identified within them : ERD drilling experience level, excess torque and drag, shocks and vibrations, hole instability, hole cleaning and resulting pack off, high side force and casing wear, high ECD due to shallow TVD, losses due to the same leak off because of the increase of the measured depth (faults presence). For the second drilling campaign (2009–2011) a new methodological approach was planned including : a new engineering main curvature design, revised operations procedures and the implementation of newer used technologies such as: Aluminum Drill Pipes (first generation) and Continuous Circulating Devices, (e-cd eni technologies).The results were extremely promising in term of drilling risks reduction and cost saving. A further enhancement step has been achieved with the third drilling campaign in 2012. Taking in consideration the achieved experience, and the lesson learned, the operation plan has been fine tuned revising the procedures, and introducing new Aluminum Drill Pipes of second generation, specifically designed for open hole sections. The new methodological approach and the deployment of the new generation Aluminum Drill Pipes (ADP #2 generation) have had as result both: an amazing improvement in drilling performances specially for 12 ¼ section and a consistent budget saving for the overall project. We can say finally that, this specially conceived drilling approach, and the new technology deployment, may represent an impressive step forward for improving the drilling performances in to the ERD wells, helping to maintain the economic threshold of the Development project.
Rock-Fluid Interactions of a Carbonate Bitumen Reservoir Rock Under Steam-Soak Conditions - Importance of Testing Under Reservoir Temperature and Stress Conditions
Authors: Dudley J.W. , Taberner C. , LaMantia B.C. , Zhang E. , McNett J. 
Published: March 2015

Abstract
Thermal recovery processes can generate substantial porosity, permeability and mineralogical changes to carbonate rocks. Understanding these changes is critical to evaluate the success and safety of the process. Tests to evaluate these changes under steam soak conditions have been done on a carbonate bitumen reservoir rock. Thermal testing done in the presence of water at 265°C and 5.1 MPa (740 psi) under unstressed conditions for ~60 days showed considerable fracturing, dolomite dissolution, calcite precipitation, magnesium-clay formation, and carbon dioxide (CO2) generation above 240°C. Calcite precipitation in the matrix porosity and newly formed fractures was extensive. However, reservoir steaming conditions will be at lower temperature (180°C), pore pressure (1.0 MPa [145 psi], with primarily steam rather than water), and under confining stress (5.8 MPa [845 psi] horizontal, 6.7 MPa [970 psi] vertical). A 17-day steam-soak test in a triaxial pressure vessel under these reservoir conditions was done on an uncleaned core sample (~80% bitumen saturation) for comparison. Water/steam flowed through the sample at intervals indicated a relative permeability of 0.3 mD. At the end of the test the accessible (i.e., water filled) pore space was filled with epoxy under stressed conditions. The remaining bitumen was removed post-test before thin section manufacture. Thin sections from the post test sample were compared to thin sections made from untested end trims and adjacent core material, and to ones from the prior unconfined, higher temperature and fluid pressure testing. The sample tested under confined reservoir conditions also shows dolomite dissolution and neoformation of magnesium-clays. The amount of calcite precipitated is minor. However, calcium sulfate (CaSO4) (not observed in the pre-tested equivalent sample) appears as a by-product of the reaction. Newly formed open fractures are not observed in the test under lower temperature, lower pore pressure, confined conditions. This work highlights the importance of mimicking expected reservoir conditions (temperature, pressure, stress & steam) for evaluating thermal decomposition effects on reservoir rocks. Future tests will help to evaluate whether longer duration heating and flow at the lower expected temperature will produce similar reaction products and physical damage (including fracturing) as more bitumen is mobilized and larger surface areas are in contact with steam.
Discrete Natural Fracture Uncertainty Modelling for Produced Water Mitigation: Chuandongbei Gas Project, Sichuan, China
Authors: Hui Mun-Hong , Glass Jerome , Harris Dan , Jia Changqing 
Published: March 2015

Abstract
The Chuandongbei project is estimated to contain a resource base of 5 TCF (1400 × 108 m3) of gas in five Triassic carbonate reservoirs. It is expected to produce at a capacity of 740 MMscf/d (2100 × 104 m3/d) for several years. There is evidence indicating that natural fractures are present in the reservoir: well test deliverabilities are substantially higher than expected from matrix permeability alone, and natural fractures are observed in cores and image logs. These potentially conductive fractures pose the risk of aquifer water breakthrough to wells.
We evaluated the impact of natural fractures on water production using an Experimental Design approach. Traditionally, fractured reservoirs are represented as dual-porosity models that simplify the matrix-fracture interaction. In this work, we instead represent faults and natural fractures explicitly as unstructured Discrete Fracture Models, which are then flow-simulated using the INTERSECT† simulator. We considered uncertain parameters associated with the fractures (density, size, and permeability) as well as matrix permeability and gas-in-place. We also evaluated the trade-off between two different well patterns, designed to mitigate reservoir compartmentalization and water encroachment respectively.
There was a concern that natural fractures would cause early breakthrough from encroaching aquifer water. However, our results showed that fractures can be beneficial to gas production in some situations but detrimental in others. This study highlights the non-intuitive consequences of natural fractures in a gas field that has an aquifer. It also points to the importance of reducing geological uncertainty (e.g., fracture characteristics and matrix properties) for effective mitigation of water production. Finally, our probabilistic approach illustrates a framework to optimize the well pattern in the face of this uncertainty.
Utility of Multiphase Production Logs in Optimising Performance of Horizontal Wells Exhibiting Crossflow
Authors: Al-Shammeri Faleh , Brett Fischbuch , Abd El-Fattah Mahmoud , Bawazir Mustafa , Al-Shabibi Hussain 
Published: March 2015

Abstract
Horizontal wells are increasingly being completed with inflow control devices (ICDs) in order to equalize the flow profiles, avoid water coning, enhance oil production, and minimize or eliminate downhole crossflow. Evaluating ICD completions is important to assess well performance, water entry intervals, completion efficiency, and potential remedial actions. Advanced multiphase production logging tools can be employed to evaluate the effectiveness of ICD completions.
This paper examines case studies of two horizontal wells drilled along well trajectories with large heel-to-toe pressure differentials. These wells were drilled in a large carbonate reservoir with moderate fracturing in areas of high structural curvature, which added to the heterogeneity. Crossflow can occur under static and flowing conditions with sufficient contrast in reservoir pressure along the wellbore. Crossflow is undesirable especially when water enters the wellbore in one region and flows into the formation at another region, thereby reducing oil relative permeability in the latter region. This can adversely affect well performance and ultimate recovery. Advanced multiphase production logs and wellbore simulation are useful in the determining minimum well production rate required to avoid downhole crossflow.
Multiphase production logging profiles were obtained for the two ICD-equipped horizontal wells in this study. These logs demonstrate the efficiency of ICD completions in minimizing crossflow when wells are produced above critical flow rates. However, the problem of crossflow remains when such wells are shut-in or produced at rates below their respective critical rates.
These results show that comprehensive evaluation of wells exhibiting crossflow is necessary to minimize or mitigate crossflow and optimize well performance. Additional ICD design enhancements are recommended to control crossflow below the critical flow rate and to minimize undesirable gas/water production.

Introduction
Horizontal wells are commonly used in the oil industry to accelerate production and lower unit development cost. Horizontal well performance is affected by many factors, including reservoir heterogeneity, well placement and completion design. In heterogeneous reservoirs, the displacing fluid (water or gas) tends to move faster in zones with higher permeabilities, which will cause early breakthrough of unwanted fluids with eventual bypass of some undisplaced oil (Ouyang 2009). This can affect the pressure distribution and hence can cause crossflow between layers.
Scale Squeeze Treatments in Short Perforation and High Water Production ESP Wells - Application of Oilfield Scale Management Toolbox
Authors: Chen Tao , Chen Ping , Montgomerie Harry , Hagen Thomas , Heath Steve 
Published: March 2015

Abstract
Inhibitor squeeze treatments have been regularly carried out to prevent both sulphate and carbonate scale depositions from reservoir to topside facilities in North Sea field since 1990s. Some of the wells, especially for the short perforation, high water production wells and relatively clean sandstone with little amount of clay material, had experienced a relatively short squeeze life with traditional squeeze treatment.
In this paper, an oilfield scale technology toolbox has been introduced to meet the challenge of squeeze treatment for high water production and short perforation ESP well, including scale inhibitor molecular design, squeeze life enhancement technique, squeeze design, inhibitor residual analysis technique, application and deployment techniques. Field trials were carried out with a satisfactory result.
This paper outlines the idea of how a special monomer was introduced into a polymer to provide improved inhibition performance and enhanced adsorption and retention capability, along with squeeze life enhancement technique through crosslinking and bridging capability with other ionic polymer additives. In addition, the squeeze life enhancement techniques through squeeze treatment design, residual analysis and deployment are discussed. A detailed lab test program to qualify the squeeze scale inhibitors will be introduced including brine compatibility, static jar test, dynamic loop test and coreflood test to qualify the scale inhibitor for squeeze application. This polymer scale inhibitor showed good efficiency in both sulphate and carbonates scale inhibition under the test conditions, along with very good adsorption and desorption property without formation damage.
This paper will give a comprehensive study of oilfield scale squeeze treatment for challenged well, which includes molecular synthesis, program of lab qualification, field design, deployment, application and monitoring. In addition, the mechanisms of squeeze life enhancement through molecular design, squeeze life enhancement and squeeze design will be addressed.
Pore Pressure Prediction in Unconventional Resources
Authors: Couzens-Schultz B.A. , Axon A. , Azbel K. , Hansen K.S. , Haugland M. , Sarker R. , Tichelaar B. , Wieseneck J.B. , Wilhelm R. , Zhang J. , Zhang Z. 
Published: March 2015

Abstract
Understanding pore pressure prediction in unconventional plays is important for executing a safe drilling strategy and for accurate production modeling. Experience from several unconventional plays highlights key aspects of pore pressure prediction work that are different from conventional exploration settings. In conventional exploration, the most common source of overpressure is disequilibrium compaction, where porosity is preserved in mudrocks as pore fluids take on additional overburden load. Traditional petrophysical methods use resistivity, sonic and density data to measure porosity and associate it with vertical effective stress (VES), which is overburden minus pore pressure. In unconventional plays, secondary pressure mechanisms and uplift require other methods because of two influences on pore pressure:hydrocarbon generation andvariations in burial and uplift history.
Both of these situations mean that the relationships between vertical effective stress (VES), velocity, density and resistivity will follow unloading paths, not compaction trends. The unloading paths vary depending on the amount of hydrocarbon generated and the amount of uplift. In organic-rich sections, an additional complication arises because pore pressure cannot be de-convolved from total organic carbon (TOC) and gas effects on shale compressional velocity and resistivity. In conventional settings, fluid gradients and contacts are used to translate measured pressure data from one location to another. In unconventional tight reservoirs, the fluids are not connected and this method will not work. Pressure data must be inferred from drilling event and diagnostic fracture injection test interpretations, and a different way to translate data between locations is required. The majority of pressure data in unconventional reservoirs shows that often, the way to translate pressure information from one location to another in the same tight rocks is to use a constant VES. This method combined with understanding variations in uplift history and hydrocarbon generation has been used to successfully predict pressure ranges in multiple unconventional plays.

Introduction
Unconventional resources plays in shale and tight rocks have become a substantial resource in North America. They are now rapidly being explored and developed outside the United States and Canada in a trend that will likely continue to grow. To economically develop these plays, wells must be drilled as cost effective as possible. To produce from these plays and forecast production, the mechanical properties of the rocks and their stress conditions need to be understood to best stimulate and complete the wells. Pore pressure prediction is integral to both of these activities.