bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced Oil Recovery After Polymer Flooding by Wettability Alteration to Gas Wetness
Authors: Cheng Changhui , Li Kewen , Liu Changwei , Jia Lin 
Published: November 2016

Abstract
Polymer flooding, as one of the EOR (Enhanced Oil Recovery) methods, has been adopted in many oilfileds in China and some other countries. Over 50% oil remains undeveloped in oil reservoirs after polymer flooding. It has been a great challenge to find approaches to further enhancing oil recovery when polymer flooding is over. In this study, a new method was proposed to increase oil production using gas flooding with wettability alteration to gas-wetness when polymer flooding has been completed. The rock wettability was altered from liquid- to gas-wetness during gas flooding. An artificial oil reservoir was constructed and many numerical simulations have been conducted to test the effect of wettability alteration on the oil recovery in reservoirs developed by water flooding and followed by polymer flooding. Production data from different scenarios, water flooding, polymer flooding after water flooding, gas flooding with and without wettability alteration after polymer flooding, were calculated using numerical simulation. The results demonstrate that the wettability alteration to gas-wetness after polymer flooding can significantly enhance oil recovery and reduce water cut effectively. Also studied were the combined effects of wettability alteration and reservoir permeability on oil recovery.
Application of Spectral Decomposition and Seismic Inversion for the Determination of Reservoir Architecture and Connectivity for Coal Seam Gas Field Development
Authors: Ahmad Mirza Naseer , Tyson Stephen 
Published: November 2016

Abstract
Coal seam gas (CSG) is naturally occurring methane found in coal seams. Fractures act as the major channel for the gas to flow and play a significant role in evaluating the practicability of the CSG exploitation. Prediction of the subsurface coal seams and the distribution of the fractures within the coal seams is a challenge. This study attempted to predict coal distribution by applying spectral decomposition and post-stack seismic inversion on a data set of the Surat Basin, Queensland, Australia. Semblance and curvature attributes were computed to determine fracture distribution within the coal seams.
According to the rock physics analysis, based on well data, coal beds had a low p-impedance as compared to surrounding lithologies. A model-based P-impedance inversion was executed to create a P-impedance volume. Extracted horizon slices successfully highlighted coal seams at different levels. Blind test for the P-impedance prediction at a well location revealed a reasonable match for coal prediction. High frequency (from 40~60 Hz) spectra delineated thin coal beds. Semblance and curvature predicted zones of high fracture density within various stratigraphic levels. The high density of fractures is along faults.
This study successfully demonstrated the prediction of coal seams and fracture distribution by using seismic inversion spectral decomposition and seismic attributes. Hence, these techniques can be used for the field development of coal seam gas.
Numerical Simulation Analysis on Degassing Structure Optimisation of a Gas-Liquid-Solid Three-Phase Separation Hydrocyclone Based on the Orthogonal Method
Authors: Zhao Wenjun , Zhao Lixin , Xu Baorui , Zhao Yu , Jiang Minghu 
Published: November 2016

Abstract
The composition of oilfield produced fluid (OFPF) is introduced, and the necessity of degassing and desanding of OFPF are illustrated. Two main degassing and desanding methods, gravitational method and hydrocyclone separation method, are respectively introduced. The latter attracts much attention due to its small occupation area and high separation efficiency. Classification and respective characteristics of solid-liquid hydrocyclone and gas-liquid hydrocyclone are described. The state-of-the-art of gas-liquid-solid three-phase hydrocyclone are briefly introduced. A new gas-liquid-solid three-phase hydrocyclone was designed based on the thought of connecting an inner-cone gas-liquid hydrocyclone with a conventional solid-liquid hydrocyclone in series by spiral flow channels. Based on the orthogonal method, influencing degree and rules of geometric parameters on the gas separation efficiency are studied using a computational fluid dynamics software FLUENT, and geometric parameters are preliminarily optimized. Study shows that degassing cone angle and gas phase overflow pipe stretch length have more significantly impact on gas-phase separation efficiency. The results provide some reference for the structure optimization of the three-phase hydrocyclone for gas phase separation.
Geomechanical Evaluation for Previously Fractured Unconsolidated Formation in Microscopic Numerical Modeling
Authors: Li Wenjing , Wu Rui 
Published: November 2016

Abstract
Traditionally, hydraulic fracturing is considered as an effective stimulating method for unconventional reservoirs with extremely low permeabilities. For poorly consolidated sandstone formations in Gulf of Mexico, East China, West Africa, etc., hydraulic fracturing is used for control or solution of sand production and formation damage more than just creating conductivity. However, it is difficult to analyze the rock mechanisms after stimulation due to the consequences of weakening of proppant overtime and changing of fracture tortuosity, etc. Stress distribution in the formation has been altered with the propagation of fractures, which make the situation more complex. For simulation of solid rock, applied by Discrete Element Method (DEM), a dynamic numerical model approached by PFC 2D Modeling is used to evaluate geomechanical properties and predict the potential formation damage. DEM is also coupled with Pipeline Network Approximation (PNA) for solid-fluid interaction. In this paper, fracture initiation and propagation, anisotropic stress boundary effect, contact forces between particles, and change of stress are investigated in microscopic system. Results demonstrate that the shear cracking mode should not be neglected in the formation of low strength and high permeability. The simulation results from PFC modeling are in agreement with the conventional numerical simulation methods. This study provides an alternative method of understanding the fracture micro-mechanism for poorly-consolidated formations, which could be applied into design and optimization of hydraulic treatment.
MPD Closed Loop Cementing in High-Pressure, High-Temperature Wells in Vietnam
Authors: Singh Harpreet Kaur Dalgit , Quoc Bao Ta , Yong Tan Chai , Nguyen Vi Pham , Wittry Alan E. , Malpas Peter , Beaugeois Aldric , Huu Nhieu Nguyen 
Published: November 2016

Abstract
Managed Pressure Drilling (MPD) technology has effectively proven that it can overcome the operational obstacles encountered when drilling difficult and challenging wells. MPD has helped many operating companies reach target depth by accurately managing the annular pressure profile of the wells in which it is deployed. However, well construction operations do not stop when target depth is reached. The well still has to be cased, cemented, and completed in order to produce and returns the initial spend on these investments.
In high-pressure, high-temperature (HPHT) well conditions where very narrow margins between the pore and fracture pressures are prevalent, conventional cementing operations become a complicated task. The tendency of inducing losses is very common, specifically during running of casing or liners, which is then further aggravated during the displacement of the cement slurry.
This was the case in one of the HPHT wells in Vietnam where losses were encountered during previous liner running operations. This situation led the operating company to decide to utilize MPD technology to improve, enhance and optimize the cementing operation. Pre-modeling to determine the correct parameters and the utilization of MPD technology allowed the mud weight to be reduced while managing equivalent circulating density (ECD) through the application of surface backpressure (SBP) to stay within the limits of the well. The application of MPD closed loop cementing on this HPHT well proved effective and provided correct parameters to successfully complete the cementing operations.
This paper will discuss the application of MPD closed loop cementing on this HPHT well in Vietnam. Specifically, it will examine the following: (1) reasons and concepts associated with MPD closed loop cementing; (2) MPD closed loop cementing pre-planning and engineering; (3) MPD closed loop cementing execution; (4) MPD closed loop cementing challenges; and (5) lessons learned and best practices.
The paper will also detail how the MPD closed loop cementing technique can be further refined and improved to be able to address other pertinent concerns experienced by other HPHT operations in Vietnam, thereby realizing the full potential and impact that the technology can help bring about in terms of drillability, efficiency, and above all safety.
The Survey for Prevention of Work-Related Musculoskeletal Disorders Among Workers Performing Manual Material Handling Work
Authors: Thongpradit A. , Dusadi-Isariyavong A. , Jongpaiboonkit A. , Kim J. , Jalayondeja W. , Mekhora K. , Jalayondeja C. , Bhuanantanondh P. , Upiriyasakul R. 
Published: November 2016

Abstract
Manual Material Handling (MMH) activities (i.e. lifting, lowering, pushing, pulling, and carrying) pose the risk of injury to the musculoskeletal system of the workers. The injuries may lead to decreased work performance, and increased errors, absenteeism and health care cost. Therefore, it is necessary to know whether the workers of one of the Oil and Gas Company in Thailand are facing with the injury problem and to find the solutions for preventing those injuries.
The procedure of the solution is walk-through survey of hazards and risks of Work-Related Musculoskeletal Disorders (WMSDs) among the workers (both onshore and offshore platforms) whose works involved in MMH tasks and providing the recommendation and followed up by Medical and Occupational Health team of the Company together with the physical therapists from one of the famous academic institute in Thailand who are collectively called "the research team".
The research team conducted a walk-through survey and performed preliminary physical examination at an onshore and all offshore platforms. The survey included characteristics of each work, intensity and frequency of workload, work environment and potential risk factors. Physical fitness assessment including muscle power and weakness was also determined.
The findings from the walk-through surveys, work procedure were analyzed to identify risk factors of work-related musculoskeletal injuries. The findings from preliminary physical examination in approximately 300 operating workers, upper cross and lower cross syndromes were found, indicating muscle imbalance in MMH workers. Task activities were analyzed on each procedure which has risk factors including awkward posture, repetitive movement, manual handling, forceful exertion, work environment, equipment, and cognitive and psychosocial issues. The research team reported risk factors with consequences and provided recommendation for each factor regarding engineering, administrative, and individual controls. For example, offshore platform has many floors which are designed for particular function (office, bedroom, dining room, etc.). Offshore workers regularly perform high repetitive stepping up and down stairs making them prone to hip and leg muscles imbalance. There is high compression at knee joint which may lead to early degenerative joint or knee pain. The recommendation is to provide properly work break and training with principle of ergonomics in workplaces including ergonomic risk factors; risk prevention; and strengthening exercise.
Findings on this study lead to the specific designed exercise program and training to counteract the effect of heavy musculoskeletal activities related to MMH in daily work. The study will also serve as a guide for developing of MMH guideline for the company.
Design of Inter-Well CO2EOR Pilot Test in Offshore Field
Authors: Murai D. , Kuroki K. , Takayanagi M. , Kawaura K. , Takahashi S. , Son L. N. , Trung P. N. 
Published: November 2016

AbstractCO2EOR has much advantage not only in enhancing oil recovery but also in CO2 storage. It is, however, necessary to confirm or estimate the technical, operational and economic uncertainties by pilot test for applying CO2EOR to actual oil fields. This paper describes the methods and the procedures to design an inter-well CO2EOR pilot test.As a result of subsurface study, the number of pilot wells is determined to be 1 injection well and 2 production wells in order to estimate CO2 areal sweep efficiency in the minimum cost. To confirm the effect of CO2EOR, well interval, cumulative CO2 injection volume and duration were determined to be 300 m, 2,000 tonnes and 2 weeks, respectively. The oil production rate begins to increase 1 month after the beginning of the pilot test, and the gas production rate and the vapor phase CO2 mole fraction also begins to increase at the same time. Then, the oil production rate reaches the peak after 1.5 months from the beginning, and the effect of CO2EOR is confirmed clearly. If oil saturation is high in the target reservoir, it will be difficult for confirming the oil bank clearly. In such case, pre-water injection before CO2 injection is found to be an effective countermeasure.As a result of surface study, a CO2 procurement method and a new platform were designed through the process optimization study. Manufactured CO2 was selected as CO2 source for the pilot test. The packed manufactured CO2 into tank containers are transported to the injection site by trucks and supply vessels. Moreover, CO2 impact study was conducted, and it is found that we can manage the potential risks related to corrosion and scale formation by using suitable countermeasure such as CRA's and inhibitors. Finally, based on the result of corrosion and scale formation studies, the operation guidelines were prepared. When the CO2EOR pilot test will be planned in any oil field, it will be possible to make the test design with the similar procedure to this study.
Challenging Operation in Block A South - How to Enhance Development Success in Abnormal Pressure
Authors: Wasawat Y. , Sittichod S. 
Published: November 2016

Abstract
Due to highly abnormal pore pressure observed in Block A South phase I development, several unexpected problems were encountered. Well targeting, operation and integrity issues were studied to minimize in the next phase of Block A South development. Phase II well designs were renewed to gain reservoir optimization. This paper presents the field mitigation and operational improvement of Block A South development from phase I to II, and the proposed guideline to later Block A South phases. For instance, Block A South phase III is another achievement to perform on these development strategies.
Block A South comprises many reservoir sections from shallow target – 2E unit, down to deep target – FM1. Pore pressure starts to ramp up at lower 2D unit and back to normal pressure at lower 2A unit. All targets were combined in a single well for reservoir maximization in phase I. However, it caused problems in terms of well operation and integrity during production. Therefore, new well design was planned to segregate reservoir targets as shallow, intermediate and deep sections to minimize operational issues. These three types of new well designs were also incorporated with pressure pregnant profiles. After two batches of fifteen wells drilled in Platform A, many operation issues, well control, borehole collapse and well integrity, were experienced. Average well cost was approximately 30 percent in excess of plan. Only half of drilled wells cannot be put on stream as planned due to cementing and integrity problems.
For Block A South phase II, pressure prediction is precisely conscious to avoid operational problems. Platform H was first developed with abnormal pressure of 1.65 sg. The new designs show success in the platform development. The Platform H new well drilling gives rise to about 20% increase in success rate from Platform A drilling. Also, average well cost is as planned. Platform G, which investigates maximum observed pressure up to 1.85 sg, exhibited all methods to avoid operational problems. 85% of wells drilled in Platform G have no problems and average well cost is within 5 percent exceeding plan. Actual operation cost and time yield better results than expected. Additionally, larger amount of volume in Platform G has been produced comparing to Platform A. The overall result of Platform G is favorable to the next phase of Block A South development.
The strategies are acceptable results to control operation with abnormal pressure. It is beneficial to Block A South development and investment. Lesson learned from these practices will provide operational improvement in later Block A South phase. These designs can be applied to other fields in the Gulf of Thailand.
Computational Method for Hydraulic Fractures Spacing of Multi-Fractured Horizontal Well in Ultra Low Permeability Reservoirs
Authors: Mingqiang Hao , Yongle Hu , Xingfan Zheng 
Published: November 2016

Abstract
Hydraulic fractures spacing of multi-fractured horizontal well (MFHW) is an extremely important item for the optimization of MFHW in ultra-low permeability reservoirs. By adopting the maximum condition that fluid at the midpoint of the two adjacent hydraulic fractures is just able to flow, the mathematical model and computational method to determine the hydraulic fractures spacing of MFHW were established based on the non-Darcy flow theory, the elliptical seepage theory, and average mass conservation law. Then the influences of the reservoir permeability, thickness, hydraulic fracture half length and conductivity, producing pressure drop on hydraulic fractures spacing of MFHW were studied quantitatively. The results show that hydraulic fractures spacing increases as the permeability increases and they have a preferable double logarithmic linear relationship; the fractures spacing decreases as the reservoir thickness and fracture half length increases, and the influences of the reservoir thickness and fracture half length on the fractures spacing are related to the hydraulic fracture conductivity. When the fracture conductivity is high, the fractures spacing is relatively broad, but with the fracture conductivity increasing, the fractures spacing growth gradually slows. The relationship between the producing pressure drop and the fractures spacing is approximately linear. The larger the producing pressure drop, the broader the fractures spacing of MFHW.
Building More Realistic 3-D Facies Indicator Models
Authors: Blévec Thomas Le , Dubrule Olivier , John Cédric M. , Hampson Gary J. 
Published: November 2016

AbstractWe present a generalization of Pluri-Gaussian Simulation (PGS) of facies that is constrained by facies transiograms instead of variograms. The main benefit is that the transiogram can be different in opposite directions whereas the variogram is symmetric. This is important as geology shows vertical (e.g. shoaling upward successions) and lateral (e.g. proximal-to-distal trends, preferential facies pinch-outs) asymmetries in facies transitions that cannot be quantified by variograms. Mathematically, the modelling approach is based on the incorporation of a spatial shift between the underlying gaussian random functions ("shifted PGS"). The matching with the transiograms is achieved by numerical computation of a multi-gaussian integral. Consequently, the modelled heterogeneities can account for a spatial polarity that may be vertical (upwards/downwards), lateral (proximal/distal), or oriented in any other direction. The method is illustrated using outcrop data from a reservoir analog deposited in a carbonate shoal environment over a lateral distance of about 2 km, i.e. equivalent to inter-well spacing in a typical hydrocarbon reservoir. A comparative study is performed between classical PGS and shifted PGS methods. The shifted PGS method successfully models the spatial ordering/asymmetry between high-permeability shoal and low-permeability backshoal facies. This new method widens the possibilities of facies modelling in complex geological environments, and produces more realistic predictive geological models.
Mechanical and Microstructural Studies of Nanoclay Based Oil Well Cement Mix under High Pressure and Temperature Application
Authors: Murtaza M. , Rahman M. K. , Al-Majed A. A. 
Published: November 2016

Abstract
To prevent cement sheath damage, a robust cement sheath is required to ensure long-term integrity and stability of the well from the imposed stresses. Successful completion of cementing job has become more complex, as drilling is being carried out in high pressure high temperature (HPHT) wells. Recently, application of nanomaterials in enhanced oil recovery, drilling fluid, oil well cementing and other applications are being explored. This paper presents the outcomes of an experimental study conducted to investigate the effect of nanoclay as an additive on the properties of Type G cement slurry under HPHT conditions. An organically modified nanoclay in which natural montmorillonite is modified with a quaternary ammonium salt is used in a cement mix, typically used in the Saudi Arabian oil field under HPHT conditions. Nanoclay based cement mixes were prepared with 1%, 2% and 3% BWOC nanoclay, along with silica flour, and other chemical admixtures. Development of compressive strength properties, microstructural studies using SEM and XRD techniques and permeability and porosity studies were conducted. It was observed that nanoclay at 1%BWOC reduced the permeability and porosity and enhanced the compressive strength with the accelerated strength development at early ages. A crystal product that is interweaved and joined together to build strong and well-proportioned structure is developed in the harden cement paste. The smaller size particles fill the capillaries of the cement paste that resulted in a dense structure of the matrix. In addition, this novel slurry formulation with low permeability and porosity and high compressive strength, is suitable in zones where the possibility of gas migration is very high.
Well Planning Optimization Process: The Collaboration Way of Saving Well Planning Time in Gulf of Thailand
Authors: Luckanakul M. , Chuemthaisong N. 
Published: November 2016

Abstract
With the world oil price crisis, reducing both well costs and drilling time are primary goal of leading E&P companies. Helping PTTEP to achieve these goals is its Well Planning Optimization Process, which shortens well planning time and increases time to optimize well design through collaborated communication among subsurface and drilling teams and advanced pre-identification of risks. PTTEP's new process gives 2 years advance time to optimize wells, supporting the company concept of "Drilling Factory Model". The well planning optimization process consists of geosciences and drilling well planning database integration, optimizing the well planning process, and a 3D visualization well planning optimization meeting. Further, it creates a collaborative environment among subsurface and drilling teams to work more efficiently and provides quick decision making for well design, optimizing targets, identifying risks, and analyzing offset wells. The significant reduction of well planning days give more time to plan ahead for future platforms. This paper presents a case study from the Gulf of Thailand using this new well planning optimization process. Also addressed is the methodology of an integrated process and data flow for better well planning.