bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Mathematical Models for Calculating the Proppant Embedment and Conductivity
Authors: Gao Yuanping , Lv Youchang , Wang Man , Li Kewen 
Published: March 2015

Abstract
Proppant embedment plays a significant role in decreasing fracture aperture and conductivity, especially for weakly consolidated sandstones, shale (oil and gas) rock, and coal beds. Empirical and semi-empirical models were usually used to calculate the embedment of proppants. However the accuracy of matching or predicting the proppant embedment using these existing models may not be satisfactory in some cases. On the other hand, it is difficult to determine the coefficients of these models. In this study, analytical models were derived to compute the proppant embedment and fracture conductivity. These new models can be used to calculate the proppant embedment, proppant deformation, the change in fracture aperture and fracture conductivity in the ideal or experimental situations of either single-layer or multi-layer patterns in the fractures under closure pressures. The new models showed that the proppant embedment and fracture conductivity are affected by the factors of closure pressure, fracture aperture, the elastic modulus of proppant and coal bed, the size of proppant, the concentration of proppant-paving, etc. Experimental data of proppant embedment in fractures and fracture conductivity of different proppants at different closure pressures were used to test the models derived in this study. The results from matching the experimental data using the new and the existing models were compared. The results showed that the new models especially the revised new models could match the experimental data in all of the cases studied. The new models for calculating the proppant embedment and fracture conductivity with a better accuracy are of great significance in selecting proppants, which is helpful to achieve high fracture conductivity and then high oil or gas productions of conventional, especially unconventional resources such as shale oil, shale gas, and coal bed methane.
The Study and Application of High Temperature-Resistant Solid Expandable Tubular Technology
Authors: Li Yiliang , Chen Qiang , Gao Xiangqian , Li Tao , Han Weiye , Bi Xiuling , Sun Qiang 
Published: March 2015

Abstract
The introduction of solid expandable tubular has been successful in the oil and gas industry, normally nitrile-butadiene rubber was vulcanized outside the tubular in order to seal off the annulus between the tubular and the wellbore, and the rubber may fail at about 400K temperature, making the tubular incapable while applied in high-temperature wells.
To solve this problem, two kinds of materials aimed at replacing the rubber were considered, one is copper which could be welded upon the tubular, and the other is the steel which is the protruding part of the SET body and can be obtained through machining process. Firstly full-scale expansion tests were performed to compare the impact of copper and steel on the expansion force, given the same length and post expansion interference; secondly the experiments aimed at understanding the sealing ability of the two new materials were carried out in the simulative environment of 673K.
The results showed that the use of copper and steel witnessed increased expansion pressure about 10% and 20% respectively compared to rubber, when the two materials were put into 673K environment for pressure testing, both copper and steel demonstrated instable results due to the irregular shape of the casing, therefore the right strategy was to set up sealing components at different part of the SET to increase the chance of success. The test results demonstrated that generally 0.5mm post expansion interference was enough for both to function well at 25MPa. The steel was more reliable than the copper since the latter demands additional process to be integrated with the SET and the field application of the casing patching in the high temperature well selected steel as the sealing material, two months after the operation, the steel passed the test of 15MPa without any leak.
We expect this research will contribute to improving the high-temperature resistant ability of expandable tubular, and will help form the technical basis for the future application in some extreme conditions.
Foam Assisted Air Injection (FAAI) for IOR at Hailaer Oilfield: Prospects and Challenges
Authors: Bo-jun Wang , Jin-zhong Liang , You-wei Jiang , Fan-zhong Kong , Jia-chun Wang 
Published: March 2015

Abstract
The Xi11-72 Block, located in Hailaer Oilfield, Inner Mongolia Autonomous Region, China, contains many ultra-low permeability (&lt;2.0×10-3µm2) oil reservoirs, with natural fractures. The reservoir temperature is 82°C; the original reservoir pressure is approximately 22.5 MPa; and the water-sensitive index of the reservoir is high (&gt;0.7). Primary production and limited water flooding experience at adjacent Blocks have shown that the recovery factor in these reservoirs is very low due to lack of reservoir energy and poor water injectivity. Since 2009, Foam Assisted Air Injection (FAAI) has been proposed, in order to block natural fractures, maintain reservoir pressure and/or increase sweeping and displacement efficiency. A series of laboratory experiments have been conducted to study the oxidation kinetics of air/air foam with oil and the blocking and displacement efficiency of air foams in different oil sands. Reservoir simulation has also been carried out for predicting the reservoir response to foam assisted air injection and optimizing the injection process. Air injection pilot test started in the field since 23 April 2011 in a well group with 1 injector and 6 producers, using a Skid-mounted high pressure air compressor (40 MPa, 7 m3/min air rate). Oxygen breakthrough was observed (oxygen contents 3.7%) on 13 May 2011, and then assisted foam was injected to inhibit air breakthrough. Up to 30 June 2011, five foam slugs had been injected into the reservoir. The field results show that air injection can enhance injection capacity; assisted foam injection can inhibit air breakthrough effectively; and oil production can be significantly increased with water cut reduced by 4%. The detailed laboratory study, field experience and prospects and challenges analysis are presented in this paper.
Effect of Porous Media on Saturation Pressures of Shale Gas and Shale Oil
Authors: Pang Jianyuan , Zuo Julian , Zhang Dan , Du Liangui 
Published: March 2015

Abstract
Shale gas and shale oil are the typical ones of unconventional reservoirs in the past decade. Some research studies focused on the effect of porous media on the dew point of gas condensate and bubble point of crude oil systems in terms of experimental and theoretical work. They reached to the contradictory conclusions. Therefore, it is of great importance to develop an effective method to predict the phase behavior of shale gas and shale oil in porous media and investigate the effect of some factors on the saturation pressures of shale gas and shale oil in unconventional reservoirs.
In this work, by taking into account the effect of capillarity on saturation pressures of gas condensate and crude oil systems, the theoretical model has been developed to predict the phase behavior of shale gas and shale oil in unconventional reservoirs. The Parachor model is applied to determine the interfacial tension of crude oil and gas condensate. Some case studies were completed to address the effect of porous media on the phase behavior of reservoir fluids. The effect tendency of some properties of porous media on the dew or bubble point of reservoir fluid is discussed in this paper.
Shallow Gas Overburden Characterisation and Full Wavefield Modelling for Gas Clouds Imaging
Authors: Ang C.T. , Othman H. , Zahir M.H. , Adnan A.G. , Ghazali A.R. 
Published: March 2015

Abstract
Imaging complex subsurface like the gas clouds has always been challenging. Gas clouds are gas accumulation, trapped as an overburden that lowers P-wave velocities (Vp) and frequencies, disrupting transmitted energy and obscures events beneath it. Attenuation of seismic amplitude due to multiple scattering in thin layering of heterogeneous media was first reported by Anstey (1971). A nonlinear full waveform redatuming method proposed by Ghazali (2011) utilized multiple scattering phenomena which described the overburden as complex scattering and translated it to a transmission correction operator. Since it is a nonlinear full waveform inversion (FWI) method, it is important to characterize the rock properties in the gas clouds to identify factors that caused the formation of shallow overburden and help to constraint non-linear inversion results.
Recent Technology Developments in Surfactants and Polymers for Enhanced Oil Recovery
Authors: Lu Jun , Liyanage Pathma Jith , Solairaj Sriram , Adkins Stephanie , Arachchilage Gayani Pinnawala , Kim Do Hoon , Britton Christopher , Weerasooriya Upali , Pope Gary A. 
Published: March 2015

Abstract
Several classes of new surfactants have recently been tested for enhanced oil recovery. These new surfactants were needed for oil field applications under reservoir conditions that made it difficult or impossible to find conventional surfactants with the desired behavior such as ultra-low interfacial tension, aqueous stability, thermal stability at high temperature, low retention, tolerance to high salinity and so forth. We illustrate results for several of these new surfactants and discuss under what conditions they are suitable, how we developed formulations using them and some of the general principles that can be applied to future applications. A common theme of this development is the need for surfactants with large hydrophobes (carbon numbers above 18) even for some light oils. A second common theme is the advantages and flexibility of propylene oxide and ethylene oxide linkages between these large hydrophobes and the sulfate or carboxylate end group. A third common theme is the advantages of highly branched hydrophobes regardless of the other characteristics of the surfactant structure help prevent undesirable viscous phases. Finally, a fourth common theme is the advantages of using surfactant mixtures with diverse structures and sizes. These common elements enable us find surfactant formulations that are highly effective and that can be made from available feedstocks at reasonable cost.
Solid Deposition in Gas Turbines of a Cogeneration Plant, Sumatra, Indonesia, Mechanism and Remediation
Authors: Hwang R. , Iwamoto J. , Coughlan P. , Kumboro D. 
Published: March 2015

Abstract
A rapid build up of solid deposits occurred in the fuel system of gas turbines of the Duri Field Cogen plant and forced to shut down the plant frequently, which resulted in a great reduction in both electric power and steam output and hence curtailed tremendously the field production of heavy oil. A comprehensive study of the fuel gas delivery system and fuel gas quality was undertaken to determine the root cause of solid deposition. The results of the study show that the pale yellowish solids recovered from the fuel system are mixtures of elemental sulfur and wax. Both elemental sulfur and wax were derived from the fuel gas delivered to the plant where they were detected in the gas at trace levels (sub ppm). The occurrence of sulfur and wax deposition was somewhat surprising as the routine monitoring of the gas showed their levels were well within operation specifications all the time. Interpretation of composition data of numerous gas samples and solid deposits combined with operation conditions of gas turbines and gas phase chemistry provided insights of the solid deposition process. The problem was caused by the significant pressure drop encountered in the fuel gas delivery system of the turbines, which induced a measurable temperature drop and the associated phase changes of elemental sulfur and wax hydrocarbons from gas phase to condense phase leading to their deposition and turbine plugging. A remediation measure was developed and implemented.
A New Model to Predict Average Pressure Difference of Liquid Droplet in Gas Well
Authors: Hai-Quan Zhong , Zhong-Neng Liu , Tong Liu , Kai Liang , Yong Ren 
Published: March 2015

Abstract
The distribution of droplet surface pressure is uneven under the action of high velocity gas streams in gas wells, and there exists a pressure difference which leads to droplet deformation before and after the droplet. Moreover, it affects the critical liquid carrying rate. The pressure difference prediction model must be determined, because of the existing one lacking theoretical basis. Based on the droplet surface pressure distribution in high velocity gas streams, a new model is established to predict the average differential pressure of droplets. Compared with the new differential pressure prediction results, the existing pressure difference prediction results overvalued by 46.0%.This article also improves four gas-well critical liquid carrying models using the proposed pressure difference prediction model, and compares with the original one. The result indicates that the critical velocity of the original models is under valued by 10% or so, due to the overestimate to the pressure difference.
Research and Application of Fire-Flooding Technologies in Post-Steam Injected Heavy Oil Reservoir
Authors: Changfeng Xi , Wenlong Guan , Jihong Huang 
Published: March 2015

Abstract
As fire-flooding has strong adaptability to develop the reservoir, it can be considered as a follow-up EOR technology of the low economic profit and high oil recovery reservoirs flooded by water or steam. Because of the complicated secondary water and steam channels, fire-flooding in post-steam-injected reservoir is far different from that in original reservoir. In this paper, the mechanism and problems associated with development engineering of fire-flooding in post-steam-injected heavy oil reservoir was studied systematically by using1D&3D physical simulation systems and reservoir numerical simulator. The temperature of combustion zone decreased and high-temperature zone enlarged because there existed secondary water formed during steam injection which could absorb and carry heat towards producers out of combustion front during fire flooding, but high saturation of water in layer caused by secondary water had less influence on the quantity of fuel deposit and air consumption. In the process of 3D fire flooding experiments, air override was observed during combustion front moving forward and resulted in a coke zone in the bottom of layer, and the ultimate recovery factor reached 65%~70% on fact that the saturation of oil within the coke zone was no more than 20%. The flooding model, well pattern, well spacing, and air injection rate was optimized according to the specific property and the existed well pattern in post-steam-injected heavy oil reservoir, and the key techniques of ignition, lifting, and anticorrosion was also selected in the same time. The pilot of fire flooding in H1 block in Xinjiang oil field was carried out since Dec. 2009on the base of these research work, and now the pilot begin to show the better performance. The production oil is about 49t/d, and the water cut is stable below 70%, the air oil ratio is about 2000m3/t, the good performance is gained for this kind of abandoned post-steam-injected heavy oil reservoir.
Oman Large Carbonate Field Production Improvement Through Integrated Well, Reservoir and Facility Management
Authors: Al-Khadhuri S.M. , Al-Harthi M.M. , Alkalbani A. 
Published: March 2015

Abstract
Managing oil fields in the best way possible has always been in the centre of interests for various oil companies. Production maintenance and optimization, deferment minimization, efficient monitoring of well, reservoir & facility performance, cross-function collaboration, and many other related issues, all represent the building blocks of a successful and efficient field management structure. This carbonate field of Petroleum Development of Oman is one of the largest fields in the Sultanate of Oman and has been running for more than four decades, and still contributes. Hence, it is becoming more important than ever to ensure that the field is managed both optimally and efficiently to adequately handle the subsurface complexity, the large stock of wells and facility units, and all other related issues, such as operations, services, human resources, etc.
An integrated Wells, Reservoir and Facility Management has been implemented to create a more focus and discipline with the aim of achieving an efficiently monitored & controlled asset as well as highly synchronised multi-team actions. The integrated management approach involves structured reservoir and field reviews conducted by integrated multi-disciplinary team, structured processes utilising Smart Field concept and Collaborative Work Environment, enabling technology to obtain data, convert data to useful information and take right decision/action at right time. Exception Based Surveillance is deployed via smart tools to closely monitor and optimise wells and facilities in real time.
As a result of the newly introduced management approach, a total of 26 sectors (more than 450 wells) have been collaboratively reviewed, resulting in:Wells book including full details on current status, challenges, potential activities and short term optimisation plan have been updated for all wells. This is considered a major achievement for this cluster of fields, where for the first time 100% wells were being properly reviewed on yearly basis.More than 150 activities have been identified as well optimisation, reinstatement, repair, data gathering and sidetrack. Excellent optimisation gain has been generated and stable production has been achieved.
Proper planning of identified activities and faster implementation resulting in better reservoir monitoring, excellent production, significant deferment reduction and lesser restoration time of failed wells and equipment.
Understanding Tight Oil Reservoir Hydraulic Fracturing Stimulation Using Two Wells Simultaneous Micro Seismic Monitoring Approach
Authors: Xu Y. , Mu L. , Yang X.G. , Zhao W. , Wang X. , Lim T.K. , Li Y. 
Published: March 2015

Abstract
The tight sand oil reservoir found in the Ordos basin is known for its very low porosity and permeability. Almost every well has been stimulated using hydraulic fracturing techniques. The average production for a vertical well is approximately 4–5 tons per day. Among such a large number of fracture jobs, enhanced production after stimulation does not always meet expectations. Since2005, hydraulic fracturing monitoring services have been carried out widely in this field to improve fracture geometry understanding and optimize well placement. With the implementation on-site, real-time hydraulic fracture monitoring, the pumping procedure can be adjusted accordingly based on the mapped microseismic events.
Based on the past hydraulic fracturing monitoring experience in this field, an average microseismic event detectable distance range around 300 m is expected for the case of geophones inside a monitor well. Two parallel horizontal wells were thus drilled at 600m apart. Horizontal section length is around 1,500m for both wells. The original hydraulic fracture plans for each well consisted of 18 stage stimulations, but were subsequently adjusted to 13stages based on real-time hydraulic fracture monitoring results. Three monitoring wells were drilled from toe to heel as shown in Figure 1. These monitor wells will also be used as water injection wells in later secondary recovery processes. So hydraulic fractures generated by the pumping from both horizontal wells are not expected to extend far enough to reach the monitor wells.
With this favorable well layout, simultaneous dual-well hydraulic fracture monitoring was proposed and conducted. In order to obtain the optimized fracturing parameters first, the initial 3 stages of each treatment well was conducted at one stage per well i.e. stimulate well-1 and then move to fracwell-2. Simultaneous hydraulic fracturing began after the initial six stages were completed.
Application of Chemical Tracers for Clean-Up and Production Inflow Monitoring with Onshore Wells in Italy
Authors: Nutricato G. , Repetto C. , D'Amico A. Santi , Oftedal G. , Faevelen E. , Andresen C. , Leung E. , Wikmark V. 
Published: March 2015

Abstract
Chemical tracers have recently been used to identify oil and water production along different intervals in open hole slotted liner completion, compartmentalized with swellable packers. The reservoir is a fractured carbonate brown field containing several sub-areas producing asphaltene and clasts in which chemical inflow tracers have provided greater understanding of characterizing the reservoir and its' well performance in deviated wells. The permanent downhole tracer systems have been successfully applied in two onshore wells in Italy. The principle of this technology is to place a number of unique chemical tracer systems in different compartments along the length of the lower completion with only minor modifications for clean-up and production monitoring. The system releases tracer into the well stream when wetted by the target fluid, oil or water. When wetted by the opposite phase they will remain dormant, meaning no tracers will be released. The application of permanent oil and water tracer systems placed at pre-defined intervals along the production zones of the wells. Upon well start up, oil samples were taken at the surface and were analyzed to identify which zones were effectively contributing to oil and water production. Permanent water tracer systems were installed aiming at detecting the onset of early water breakthrough. After water break-through has occurred, a regular sampling program is performed and samples analyzed to identify the location of water production to understand the water profile evolution over time. Swellable packers have been used to segment the horizontal sections for the purpose of selective zonal stimulation and to optimize future water shut off intervention by treating the offending zones based on tracer detection. This paper will discuss an innovative wireless approach using chemical inflow tracers as the technology enabler with field proven case studies for clean-up verification, identifying where water and oil is flowing, assess stimulation job effectiveness and estimate relative flow contribution between intervals. Lessons learned for future installations will also be discussed.