bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rock Mechanical Properties of Shale Gas Reservoir and their Influences on Hydraulic Fracture
Authors: Li Qinghui , Chen Mian , Zhou Yu , Jin Yan , Wang Fred P. , Zhang Rixing 
Published: May 2016

Abstract
Each shale gas play is unique and the stimulation and completion method should be determined based on individual attributes. Selecting the completion style for an emerging shale play should begin in the laboratory rather than copy successful cases. An understanding of the rock mechanical properties is essential to help understand how the shale reservoir should be completed.
We conducted triaxial compression tests for specimens from North America and South China. The failure modes and mechanical behaviors are analyzed. A new method combines rock mechanical properties and mineralogy to quantify the brittleness was derived and the practical use is demonstrated afterwards. Natural fracture analysis from core and borehole image are conducted and potentially active fractures, which could be most important hydraulic conduits and another index of the fracability, are identified through a three-dimensional Mohr representational method.
The results of this study revealed that black shales are usually more brittle than imagined. Splitting and splitting-shear hybrid failure modes are the main failure modes under low confining pressures, while shear failure modes predominate under higher pressures. Types of shale, burial depth, coring direction and confining pressures are all affecting the mechanical behavior of specimens. The brittleness characterization of shale samples from China is similar to that from America. Compared with North America, shale from South China has higher strength and Young's modulus, while lower Poisson's ratio. A systematic approach of designing completion and stimulation is proposed based on brittleness, closure stress and hydraulic fracture width.
The analyzing results from two shale gas wells verified the value of this method. Brittleness calculating results tallied well with initial production of these wells, indicating good application prospects. Calculation of strength properties, closure stress and fracture width can be practical useful in selecting and designing stimulation measures.
Formation Damage and Treatment of Offshore Water Disposal Wells in Saudi Arabia: Case Studies
Authors: Mei Ken , Qahtani Hassan B. , Al-Kuait Abdulmohsen S. , Sukkar Luai A. 
Published: May 2016

Abstract
In one Saudi Aramco offshore oil field, the formation fluids are being produced from different platforms and transported to one onshore gas-oil separation plant (GOSP) where the produced water is removed from the hydrocarbon stream. The produced water is injected back to highly permeable formations through disposal wells with no interruption. In this way, the water disposal system is an integral part of the hydrocarbon recovery system. A failure of one of the disposal wells could adversely affect oil production. Saudi Aramco petroleum engineers are placing more and more attention on water disposal wells as a higher volume of produced water from the increasing hydrocarbon production rates has to be disposed of continuously every day.
The primary objective of surveillance on the disposal wells is to keep an extra disposal capacity for continuous oil production from the field and to precisely monitor the decline rate of the capacity of each disposal well. Areal sweep efficiency and pressure maintenance are not the surveillance scope for water disposal wells in our case. Few technical papers have been published that discuss the problems a water disposal system may have in a matured field and address issues such as surveillance of well performance and water quality, formation damage mechanisms, treatment and so forth.
In this paper, the existing water disposal system in a matured offshore oilfield is briefly described and discussed with the surveillance of well performance and the quality disposal water, potential problems, and the evolution of the surveillance philosophy. The reasons why most disposal wells experienced severe injection decline are analyzed and discussed in detail. Historic treatments were summarized with actual outputs demonstrating" ineffective" treatments for the issues discussed. After several trial tests, one customized chemical treatment recipe was developed to effectively tackle the issues and actual well data is included showing the effectiveness of those treatments. A new surveillance strategy for better monitoring of well performance and the quality of "waste" fluid is also discussed in this paper.
It can be concluded from our work that formation damage exists extensively in wastewater injection wells and that it greatly influences the performance of disposal wells. Any treatment for restoring the injection capacity of water disposal wells impaired by low quality water is expensive. Any successful treatment is rooted into the detailed analysis of the problems. Implementation of a proper surveillance program and appropriate processing of the injection fluid is also vitally important for wastewater management.
Modelling Well Performance Forecasting of Complex Volcanic Reservoir
Authors: He Liu , Yingan Zhang , Honglan Zou , Yang Gao 
Published: May 2016

Abstract
The formations of DaQing gas field are mainly volcanic reservoirs which have the characteristics of low permittivity and complex formation structures. Most of these wells need fracturing remodeling to meet the standards of industrial gas stream, and also, the gas productivity tests as well as the pressure recovery tests conducted on these wells are different from other regular gas reservoirs. Considering the nature of the volcanic reservoir, such as dissolution pores, karsts caves, natural fracture development, we built two mathematical models of dissolution pores development and natural fracture development under both of the Darcy flow conditions and Non-Darcy flow conditions separately to predict the production of triple porosity reservoir after gas reservoir well fractures. By using the Laplace transform and numerical inversion, the equation to calculate production of complex volcanic gas wells is obtained. Based on these researches, law of volcanic reservoir productivity is investigated. The theoretical data are compared with the practical data collected from the field operation. The comparison results reveal how the parameter of the fluid volume, proppant indexes, and conductivity of artificial fracturing induced fractures and length of fractures change affect the productivity. The research work reported in this paper provides theoretical support on the optimization method of fractured wells design of volcanic gas reservoir.
China's Future Energy Needs
Authors: Hornyak Albert , Vossoughi Shapour 
Published: May 2016

Abstract
China is the world's second-largest consumer of energy and the third-largest producer of energy. China consumes more than 10 percent of the world's energy, following only the United States. It is projected between 2015 and 2020 the world oil supply will flatten and then slowly decline. In contrast to declining oil reserves China's oil needs are projected to more than double by 2030.China's electricity and natural gas demand is expected to triple while reliance on coal is expected to double. If China maintains its current pace it will overtake the United States and become the largest consumer and producer of energy in the world.
China's current plan to meet future energy needs is very much dependant on fossil fuels. According to industry reports coal (60%) and oil (27%) will account for 87 percent of China's total energy demand by 2030. If China does not utilize new cleaner burning initiatives into their coal-fired power generation plants China will continue to pollute the world and may cause irreversible damage. The World Heath Organizations reports that within the next two decades China will become the largest emitter of green house gases in the world. The effects of pollution on the Chinese economy are enormous. The World Bank estimates pollution costs China eight percent of GDP.
Finally, if energy demand continues to grow at present rates, China may begin to crowd the United States and others out of the global energy market. The United States as the top consumer of energy will either have to curb consumption to make room for China, or will have to find a way to curb China'smassive energy needs. Both China and the United States need to realize the powerful incentives which would be gained through mutual cooperation in the search for new energy reserves and energy sources.
An Effective Acid Placement Technique to Stimulate High-Temperature Sandstone and Carbonate Formations
Authors: Gomaa Ahmed M. , Cutler Jennifer , Qu Qi , Boles Joel , Sun Hong 
Published: May 2016

Abstract
Viscoelastic surfactant-based acids have been used in the field for several years, and have been the subject of many laboratory and field studies. An extensive literature survey revealed that corrosion inhibitors and high-temperature dramatically weaken the surfactant structure and significantly reduce its viscosity. Therefore, these fluids are typically limited to placement in relatively low-temperature formations.
This study was conducted to evaluate a new VES system that can form a gel and maintain useful viscosity at high temperature. The effects of temperature, initial HCl concentration, corrosion inhibitor concentration, surfactant concentration, and breaker type and concentration on the viscosity and corrosion rate of the new VES were investigated. Additionally, a core flood study was conducted using Indiana limestone and Berea sandstone cores to evaluate the diversion ability of VES system.
Experimental results show that because of the low viscosity of the new VES system at live condition, it can be used at an initial HCl concentration of 15 wt% or higher. Even in the presence of a high concentration of corrosion inhibitor, the new VES system maintained its viscosity at 300°F. With no breaker in the system, the viscosity of the new VES system was stable for at least 3 days, and viscosity increased with surfactant concentration.
Breakers based on mineral oil caused a smooth viscosity decline, while breakers based on mutual solvent caused instantaneous viscosity reduction. The pre-flush stage of mutual solvent did not prevent gel formation during acid neutralization. Mixing the new VES in 5 wt% NH4Cl brine formed a gel at surface. The new VES acid system increased the pressure drop by a factor of 18 inside Berea sandstone core and resulted in a 60.5 % permeability enhancement. Corrosion inhibitor reduces viscosity of the new VES system, while intensifier has nearly no effect. Also, increasing the concentration of either corrosion inhibitor or intensifier reduced the corrosion rate of the new VES system. Therefore, in some cases, a higher intensifier loading can be recommended to achieve viscosity goals along with corrosion protection.
The Mechanism of Leakoff Reduction of Clean Self-Diversion Acid in Acid Fracturing
Authors: Mou Jianye , Cai Xin , Liu Ming , Zhang Ye , Zhang Shicheng 
Published: May 2016

Abstract
Leakoff has been regarded as the main factor that limits fracture propagation and live acid penetration distance in acid fracturing. Reducing acid leakoff is a common measure to increase effective fracture length. Due to cleanness and leakoff reduction, clean self-diversion acid (VES: viscoelastic surfactant acid) has been used in acid fracturing. So far the mechanism of leakoff reduction by VES acid is interpreted qualitatively, and performance evaluation of leakoff reduction is based on laboratory results. However, laboratory results cannot be generalized to formation conditions directly. In this paper, we developed a model to simulate VES acid leakoff. The model consists of two parts: the acid invaded zone and the compressed zone. Coupling of the two zones forms the VES acid leakoff model. In the invaded zone, we built a VES wormhole model, which simulates acid flow, acid-rock reaction, porosity variation, and acid viscosity variation. The VES wormhole model predicts the pressure field, the flow field, acid concentration distribution, cation concentration distribution, VES concentration distribution, and viscosity distribution. For the viscosity variation due to acid-rock reaction, we use a correlation of viscosity as a function of pH, temperature, cation concentration, VES concentration, and shear rate based on experiment results. With the model, by extensive numerical simulation, we analyzed wormhole progation behavior under VES acid flooding and put forth the mechanism of VES acid leakoff reduction. The study shows that wormholing and viscosifying have competitive effect on leakoff. Wormholing decreases flow resistance, while the viscosifying and the increase of the width of spent acid zone raise flow resistance. Wormholes have fewer branches under VES acid compared to regular acid. For reservoirs with small compressibility, for example oil reservoirs, VES acid has relatively small effect on leakoff because compressibility has dominant effect on leakoff ; while for reservoirs with large compressibility, for example gas reservoirs, VES acid has a significant contribution to leakoff reduction because viscosity has a dominant effect on leakoff.
Natural Gas Exploration in Kuqa Foreland Thrust Belt
Authors: Xie Huiwen , Li Yong , Huang Shaoying , Lei Ganglin 
Published: May 2016

Abstract
The Kuqa foreland thrust belt, which has superior petroleum geological conditions and lines of structural belts, is an important target for natural gas exploration in Tarim basin. But owing to the bad surface conditions, the complex deformation of the underground structures and the poor quality of seismic data here, it is difficult to define the trap and evaluate the reservoir. Since the discovery of the Kela 2 gas field and the Dina 2 gas field, there was no further progress at one time.
Recently, a serie of technique research aimed at the targeting Cretaceous subsalt rocks strata in Kuqa foreland thrust belt has been carried out: The application of wide line and large geophone array seismic acquisition technique in complex mountainous areas can effectively improve the quality of seismic data; With 3D anisotropy seismic pre-stack migration technique, the seismic imaging and migration homing problem of the complex over-thrust and the irregular object is effectively resolved; The modeling technology of the compressive salt-related structures effectively guides the high and steep complicated structure interpretation; The technique of recognizing and forecasting of the thick conglomerate layer in shallow strata can be applied to build the seismic velocity field and confirm the traps.
The great progress in exploration technology has enriched the geological understanding and brought about three major changes in exploration: In Kelasu structure zone, the exploration target turns to deep strata from the shallow ones; In eastern Kuqa depression, it goes to tight sand gas exploration while in the western part it switches to the lithologic hydrocarbon reservoir exploration. In this way, the subsalt layer hydrocarbon exploration has made a great breakthrough, companied with a new gas exploration upsurge. In five years, Dabei-3, Keshen-2, Keshen-5, Bozi-1, Keshen-8 and many other gas reservoirs have been found. 800 billion cubic meters of natural gas has been confirmed and about 30 important traps have been reserved. The total natural gas reserves amount has exceeded 2 trillion.
Response Analysis of Pipeline Subjected to Active Fault
Authors: Jiao ZhongLiang , Wang BaoQun , Wu Bin 
Published: May 2016

Abstract
Aiming at the requirement of pipelines' seismic design, the code of "Seismic Technical Code for Oil and Gas Transmission Pipeline Engineering" was published, and the code presented the seismic design method of pipelines subjected to active fault, and pointed out that finite element method is necessary when pipeline is axial compressed. Based on the strain calculation method proposed by the code, this paper discuss the influence factors such as pipeline-fault angle and pipeline buried depth, then presents pipeline strain variation trend when subjected to active fault movement. Meanwhile, this paper adopts finite element method to analyze pipeline strain distribution, and points out that pipeline strain is composed of axial tension/compress strain and bend strain, which could explain the pipeline strain distribution, and the elliptic phenomenon of pipeline should be considered in the future research works and code revision. This paper provides the technical reference for pipeline seismic design.
Integrated Geological, Petrophysical and Geophysical Characterisation of a World Class Shale Gas Play, Horn River Basin, British Columbia, Canada
Authors: Potma Ken , Jonk Rene , Davie Matthew , Austin Nick 
Published: May 2016

Abstract
The Devonian-aged strata of the Horn River Basin, located in northeast British Columbia, Canada, host a giant shale-gas play with an estimated OGIP of 14.2 trillion cubic metres (500 TCF). Ten distinct mudstone reservoir and non-reservoir lithofacies can be recognized in core, differentiated with a suite of wireline well logs and inverted from seismic data. Reservoir lithofacies are rich in total organic carbon (TOC) and the predominant pore type is organic micro-porosity. These lithofacies are predictable within a sequence stratigraphic framework which allows us to interpret the depositional processes, map the resulting depositional geobodies and thereby optimize the development plan.

Motivation
Lithofacies classifications associate sedimentary characteristics with depositional processes. In petroleum exploration and development, lithofacies classifications are typically tied to porosity and permeability - the two key parameters that control productive capacity. A powerful tool is obtained when the lithofacies classification is constructed within a predictive sequence stratigraphic framework that integrates geological and geophysical data. Although depositional processes and environments for fine-grained, organic-rich sedimentary rocks are not as well established as those for coarse siliciclastic or for carbonate systems, herein we show how we adapted a "conventional" workflow to allow such prediction in an "unconventional" shale hydrocarbon system.
Production Transformation in Horizontal Wells
Authors: Edward B. , Katavut C. , Chantarat L. , Gordon Goh K.F. , Wachiragorn P. 
Published: May 2016

Abstract:
Pan Orient Energy (POE) recognized that horizontal wells maximise fractures' intercept, thus improving drainage area for oil recovery. However, production data indicated horizontal wells on standalone basis, cannot guarantee the optimum performance required. The negative impact of downhole inflow imbalance along the entire horizontal wellbore is much worse in fractured reservoir due to the high contrast in permeability between macro fractures, micro-fractures and the core matrix inflow. In order to provide an inflow-control defense system downhole, ICD's application has been tested successfully in Bo Rang field and proved to normalise non-uniform influx to control water influx, thus optimising oil reciprocally.
With its single-string and one run-in-hole trip, ICD's execution is cost-effective and a low-risk yet simple operation in terms of safety, i.e. comparable to running standalone screen procedures. Upon overcoming the shallow volcanic fractured reservoir workover and lift challenges, this ground-breaking technology application success on the ICD pilot recompletion has bear fruits over the following production impact as such:Actual oil production exceeds targeted rate-improvement two-fold in Bo Rang Well A first pilotTransforming production for high water-cut well from the conventional choking-back and cyclic on-off production to the ICD's increased surface rate production with ESP lift and higher overall oil4 ICD's recompletion well installed to-date with all achieve and/or exceed oil-incremental expectation and water-cut reduction targetExisting high-water cut (WC=90%) old wells are revived with significant oil-incremental by ICD's re-distributed

Inflow across major fractures and /or micro-fractured horizontal well production
This is the first successful ICD's application in shallow fractured volcanic reservoirs worldwide, unlike in the common sandstones or carbonate fractures. The post-job production-upside significance of ICD's application in such worst-case scenario of recompleting in existing high WC wells has provided optimism and way-forwards to apply it in new sidetrack wells and the adjacent sandstones reservoir in the on-going development campaign.
Pressure Drop Reduction of Stable Water-in-Oil Emulsion Flow: Role of Water Fraction and Pipe Diameter
Authors: Al-Yaari M. , Al-Sarkhi A. , Hussein I. , Abbad M. , Chang F. , Abu-Sharkh B. 
Published: May 2016

Abstract
Emulsified acids provide significant benefits in stimulating oil and gas wells by slowing the reaction rate with carbonates and reducing corrosion in the tubular goods. However, pumping emulsified acids can result in high friction losses and hence reducing stimulation effectiveness. Therefore, reducing friction pressure loss is an important factor in expanding the application of emulsified acids. This experimental work aims to investigate a possible friction reduction through the control of water fraction as well as pipe diameter.
Surfactant-stabilized water-in-oil emulsions with different water fraction were created. Pressure drop measurements of the flow of all formed emulsions were conducted in a flow loop consisting of 1-in and 0.5-in horizontal pipe diameters at 77 oF emulsion temperature. Such results were explained in terms of emulsion viscosity as well as the average droplet size and distribution of the emulsion dispersed phase (water).
The results showed that stable water-in-oil emulsions are strong function of the dispersed water fraction. As water fraction increased, emulsion pressure drop increased. This was attributed to the increase in the emulsion viscosity due to an increase in the water fraction. Therefore, water-in-oil emulsion frictional pressure drop can be reduced by reducing water fraction. In addition, decreasing pipe diameter from 1-in to 0.5-in resulted in up to 74% reduction in emulsion friction factor and such dependency was clearer as water fraction increased.

Introduction
Under certain conditions, the injection of water into a crude oil pipeline results in a significant reduction of pressure loss, thereby facilitating oil transportation. Therefore, cocurrent flow of oil and water in pipelines has attracted the interest of researchers (Russel et al. (1959), Charles et al. (1961), Hasson et al. (1970), Oglesby et al. (1979), Arirachakaran et al. (1989), Valle and Kvandal (1995), Beretta et al. (1997), Angeli and Hewitt (2000), Soleimani et al. (2000) and Al-Yaari et al. (2008, 2009 & 2012)). However, the majority of studies reported in the literature, is mainly focused on either oil-water flow patterns or separated flows. The pipeline flow behavior of water-in-oil and/or oil-in-water emulsions has received less attention compared with separated flows.