bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydraulic Fracture Initiation while Staged Fracturing for Horizontal Wells
Authors: Lv Zhikai , He Shunli , Gu Daihong , Zhang Hongling 
Published: March 2015

Abstract
Hydraulic fracturing is recognized as a successful stimulation technique for enhanced hydrocarbon recovery from unconventional tight reservoirs. Technological advancement in directional drilling has led the petroleum industry to drill arbitrarily oriented wellbores for exploitation of reservoirs, which otherwise could not be economically produced. Prediction of fracture initiation from such wellbores is therefore essential for petroleum industries to undertake efficient hydraulic fracturing stimulation tasks.
In a hydraulic fracturing process, fluid is injected under pressure through the wellbore in order to overcome native stresses and to cause failure of rocks, thus creating fractures in a reservoir. These fractures create a passage through which hydrocarbon flows into the well from the shale formation. Based on the superposition principle and elasticity theory, a total stress field mathematical model while staged fracturing for horizontal well is abstractly presented in this paper, considering systematically influencing factors such as wellbore pressure, in-situ stress distribution, seepage effect of fracturing fluid, and induced stress produced by hydraulic fracture. The law of initial and subsequent fractures initiation is studied.
The results show that the initial fracture initiation is affected by the wellbore azimuth angle, and it is easy for transverse fractures to form when the minimum in-situ horizontal stress along the wellbore direction. The stress distribution around wellbore is influenced by induced stress field, and when the initial fracture height is constant, the effect decreases gradually along wellbore direction until the combined stress field tends to the in-situ stress field. In a certain position from the initial fracture, the bigger the fracture height, the greater the induced stress, and in particular, the influence on induced stress along the wellbore direction is more obvious. Induced stress can increase subsequent fractures initiation pressure, whose level will reach 30% and increase as the fracture height increases. When fracture height is constant, the increase level of initiation pressure decreases rapidly with the increase of fracture spacing.
There is well coincidence between computational solution and measured result. Results from the analytical and numerical models used in this study are interpreted with a particular effort to enlighten the causes of abnormally high treating pressures during hydraulic fracture treatments, as well as engineers study recovery techniques.
Advanced Oxygen Enrichment Technology for Cost Effective Sulfur Recovery Processing Facility Applications in China
Authors: Wong Vincent W. , Chow Thomas K. , Zhan Yangchun 
Published: March 2015

Abstract
A global trend towards increasingly-stringent environmental regulations of sulfur dioxide emissions to improve air quality is faced. China has been adopting progressive policies for improvement of air quality. Recent industry trends focused on producing cleaner air and fuels around the globe, especially in China, have generated significant demand for additional hydro-desulfurization and sulfur recovery capacities in both new and existing refineries and gas plants. Oxygen enrichment technology frequently offers the most economical route to achieve the desired increase in sulfur processing capacity with high recovery efficiency.
This commercially proven technology has excellent operating safety records as witnessed by the safe operation of over 300 SRU/TGTU plants in USA, Canada, Europe, Middle East, South Africa and a newly installed facility in Panjin, China.
This paper provides a technical background of oxygen enrichment technology, and discusses the various economic, logistical, process and operational advantages that can be realized through its implementation.
Multistage Temporary Plugging Acid Fracturing Technology Application Long Interval Heterogeneous Carbonate Reservoir
Authors: Jianming Sheng , Xinrong Wu , Aijun Huang , Anpei Wang , Bin Zhao , Bo Geng 
Published: March 2015

Abstract
Sichuan Puguang Gas Field is high sulfur content carbonate gas reservoir buried in the depth of 4775.4~6461.3m. In the produced gas, the average content of methane is about 75%, H2S 15% and CO2 10%. The thickness of producing formation is between 176.4m~838.8m, on average, the thickness is 395m. The formation is severely heterogeneous, including type?, type? and type ? reservoir which is developed alternately. The proportion of type ? reservoir is more than 50%, the total ratio of type ? and type ? is more than 90%. Gas testing in early exploration phase obtained no commercial gas production in type ? and type ? reservoir. Using the cores from Puguang gas field reservoir, fracture flowing capacity experiments have been conducted by using various acid fracturing fluid systems and different technical models. Considering geological characters, completion situation and surface gathering conditions, large-scale temporary plugging multistage injection acid fracturing technology is selected. The plugging ratio of the temperature-controlled temporary plugging agent is more than 90% and the plugging strength is greater than 15MPa. The pump discharge capacity of the new gel acid system is 10 m3/ min. The operating friction is 30% of that of clear water. The viscosity is more than 30mPa•s after being kept for 180min under 130?. 34 wells have been acid fractured by using this technology, and the average open-flow capacity of a single well is 487.8×104m3/d. And after having been producing for one year the average gas production of a single well is 69.3×104m3/d. Multistage temporary plugging acid fracturing technology application to long well interval heterogeneous carbonate reservoir integrated with acid fracturing technology and optimized design is technical guarantee to develop Puguang Gas Field efficiently and safely, and at the same time it will also be a technology backup to develop some similar gas fields.
Production Performance Analysis of Hydraulically Fractured Horizontal Wells in Sulige Gas Field
Authors: Ruilan Luo , Yongxin Han , Shuming Yu , Jiwu Fan , Wen Xu , Ke Yuan 
Published: March 2015

Abstract
Sulige gas field is the largest tight sand gas field in China. In order to boost gas production of individual wells and to maximize economic return, hydraulically fractured horizontal wells are widely applied in Sulige gas field in recent years. Influenced by special geologic condition and stimulation, the production performance of hydraulically-fractured horizontal wells in tight sand gas reservoir is obviously different from that of conventional gas wells, such as:? The dominant flow regime is linear flow rather than pseudo-radial flow and this flow regime may continue for several years;? The dynamic reserve, drainage area and productivity of producing wells vary with time quickly, especially in the early stage of production.
By correctly identifying the percolation characteristics and production performance of hydraulically fractured horizontal wells in tight sand gas reservoir and combine with modern gas production analysis technology, 137multi-stage fractured horizontal wells in Sulige gas field have been analyzed. Then a prediction chart of estimated reserves and new method of dynamic deliverability evaluation for Sulige multi-stage fractured horizontal wells are established. With these chart and methods, by using early stage production data, the dynamic reserve, drainage area and deliverability of multi-stage fractured horizontal wells can be predicted effectively with elapsed production time. In this paper, ultimate recoverable reserves, drainage sizes, drainage lengths and drainage widths of 57 multi-stage fractured horizontal wells in Sulige gas field are estimated.
The results show that, in Sulige gas field, the average ultimately dynamic reserves and drainage sizes of multi-stage fractured horizontal wells are 2.8to 3.4 times that of offset fractured vertical wells, and the average initial deliverability of multi-stage fractured horizontal wells is 4.0 to 5.0 times that of offset fractured vertical wells. Based on these data, the reasonable well spacing and gas flow rate of Sulige gas field are suggested.
Polymer Flooding for Middle and Low Permeability Sandstone Reservoirs
Authors: Xiaoqin Zhang , Wenting Guan , Feng Pan 
Published: March 2015

Abstract
Daqing Oilfield is a heterogeneous sandstone oilfield with multi-layers. Polymer flooding in primary oil layers has obtained significant technological and economic effects. As the recoverable reserves of primary oil layers decline yearly, secondary oil layers have become the focus of industrialized polymer flooding since 2003. Compared with the primary layers in Daqing Oilfield, secondary layers are of thinner thickness, lower permeability, narrowly-developed channel sands and poor continuity of sand bodies. There are four lower aspects and two imbalances in the dynamic performance of polymer flooding in secondary layers. Due to the geological properties and recovery performances of secondary layers, measures are taken to further enhance their recovery factors. Polymer flooding objectives are carefully selected, layers are carefully divided, well spacing between injectors and producers is shortened, and separated-layer polymer injections are widely utilized. Inconsequence, better development has been obtained.
The Use of "Dope-Free" Tubulars in Petroleum Well Completions
Authors: Funes Alejandro , Figini Fernando , De Franceschi Esteban , Actis Goretta Emiliano , Castineiras Tomas , Wang Xiuli , Economides Michael J. 
Published: March 2015

Abstract
Although invariably well tubulars have been connected with a thread compound to prevent corrosion and the galling of the metal itself, innovative technologies have allowed the introduction of dope-free connectivity by engineering the connections at the end of pipe sections. Avoiding the use of dope compounds has apparent benefits, one of which is the prevention of formation damage. Another is the efficiency and reliability of the operation itself, removing a cumbersome, albeit routine job, a major advantage in the hectic time of a drilling rig's operation.
During the connection assembly a portion of the thread compound is exuded outside the connection and gets access to the well fluids through the tubing and annular space. Laboratory studies by us with core experiments, presented in this paper, show that the dope forms a suspension which penetrates and damages the formation. The damage is severe (more than 99 percent) and will be present in any well injection service. For production the issue is different and will depend on the reservoir permeability and the ability or lack thereof of the dope compound to penetrate the rock matrix or whether it will form a removable filter cake.
The reason that this problem has not gained widespread notice is perhaps because the problem has a narrow application of formation permeability, one that we delineate in this work. Additionally, we present evidence that the dope can be washed off usually by simple flow of reservoir fluids and/or brines orit can be partially dissolved by simple solvent treatments employing toluene orxylene.
We present here the clear benefits of using dope-free pipe connections by quantifying the negative effects of the alternative. Production equations using a dope-induced skin effect are presented, showing the detrimental impact on well performance.
From Molecular Dynamics to Lattice Boltzmann: A New Approach for Pore Scale Modelling of Multi-Phase Flow
Authors: Gong Bin , Liu Xuan , Yu Jiapeng 
Published: March 2015

Abstract
Absolute permeability tensor and relative permeability curves, which are the two most important properties in prediction of subsurface flow dynamics, are both obtained from lab experiments traditionally. Although the measuring approaches have been widely used and results are largely accepted for many years in most cases, the lab experiments are usually expensive, not robust especially for low and ultra-low permeability core measurements, and can not always be repeated for different fluids or under different flow scenarios.
Multi-phase modeling based on geometry information of cores obtained by Micro X-ray Computed Tomography becomes an emerging technology that tries to yield rock properties directly. Among all the methods of pore scale modeling, Lattice Boltzmann Method (LBM) shows an apparent advantage in terms of computational efficiency, readiness for parallel computing, and capability of modeling flow with complex boundary conditions. Several multi-phase LB models have been proposed in the last two decades, with successful implementation in the simulation of actual single component two phase (liquid and vapor) flow problems. But for actual solid-fluid systems, most models suffer from the parameters fitting in order to match the experimental results.
In this study, we propose to integrate Molecular Dynamics (MD) simulation with Lattice Boltzmann method to solve this problem. The basic idea is to first construct the molecular model based on the actual components of the rock-fluid system. Then MD simulation is performed to compute the interaction force between the rock and the fluid of different densities. MD simulation results indicate that the composition of the forces is a surface force as a nonlinear function of fluid density. This calculated rock-fluid interaction force, combined with the fluid-fluid force determined from the equation of state(EOS), is then used in LBM modeling. Without parameter fitting or assuming the linear relationship between the rock-fluid interaction force and fluid density, this study presents a new systematic approach for pore-scale modeling of multi-phase flow.
We have validated this approach by simulating a two-phase separation process and gas-liquid-solid three-phase contact angle. The success of MD-LBM results in agreement with published EOS solution and experimental results demonstrated a breakthrough in pore-scale, multi-phase flow modeling. Based on an actual X-ray CT image of a reservoir core, we applied our workflow to calculate absolute permeability of the core, vapor-liquid H2O relative permeability and capillary pressure curves. With the application of this workflow to a more realistic model considering actual reservoir rock and fluid parameters, the ultimate goal is to develop an accurate method for prediction of permeability tensor, relative permeability and capillary curves based on 3D CT image of the rock, actual fluid and rock components.
Qualification Testing of Large Bore, HP Tubing Retrievable Safety Valves for Gas Wells
Authors: Ali Mohammad A. , Ahmari Abdulrahman S. 
Published: March 2015

Abstract
Over the past decade, the role of natural gas has become increasingly important in fulfilling the ever-increasing energy needs of the world. Natural Gas has not only become an integral part of the world's energy portfolio but also offers a cleaner and more efficient fuel to help reduce carbon emissions when compared to oil. Recently, Saudi Aramco has made three major offshore, high pressure, non-associated gas discoveries. A large bore completion design was selected for these fields in order to bring these discoveries on line quickly and cost effectively.
The surface controlled, sub-surface safety valve is a critical component of the asset integrity management program for these gas wells. In order to meet the requirements of completion design and reservoir pressure, the world's first 9-5/8in 10,000psi rated TRSSSV were developed tested and qualified for these developments.
As part of qualification testing, high rate slam closure testing of the TRSSSV was carried out at the Southwest Research Institute and at GL Nobel Denton facilities. The objective of the tests was to ensure that TRSSSV closes, seals and continues functioning after a slam at the highest anticipated flow velocity in the wells. Additionally, slam test results were used to design surface and subsurface components that are required to operate the TRSSSV and must be capable of withstanding the shock load produced by a slam closure.
Two leading completion companies were selected to develop and provide the TRSSSVs for these projects. Both designs suffered initial failures, required significant modification, and underwent extensive tests before the final designs were successfully tested.
This paper discusses the basis of design, test criterion, results and lessons learned from the slam testing of the world's first 9-5/8in, 10,000 psi rated TRSSSV. The paper also provides an overview of the two test facilities used, their limitations, and recommendations for future tests.
Use of High Resolution Sequence Stratigraphy in Building 3D Reservoir Geological Model - A Case Study from Kuwait
Authors: Neog Nilotpaul , Chakraborty Subrata Kumar , Rao N.S. , Perrin Christian , Pattnaik C. , Al-Ashwak Samar , Al-Mayyas Rawan Hussain , Al-Darm Areej , Al-Ateeqi Khalid 
Published: March 2015

Abstract
A number of structures are producing hydrocarbons in commercial quantity from the carbonate reservoirs of Middle Marrat Formation in the Northern part of the State of Kuwait. Seismic resolution of these deep carbonate reservoirs of Toarcian age is strongly affected by multiples from overlying Gotnia-Hith salt-anhydrite layers impacting true understanding of the internal depositional architecture from seismic data making it difficult to make realistic geological models.
An extensive coring campaign adopted over a period of time for improving the understanding of depositional settings and diagenetic processes in these reservoirs and subsequent studies helped in developing a correlation based on sequence stratigraphic principles. In the Middle Marrat Formation seven cycles with sequence boundaries and maximum flooding surfaces were identified. The best reservoir facies are located in High Stand Tract, corresponding to the progradation of the carbonate platform in the form of clinoforms sloping towards the basin.
3D geological model was built with a framework base on this correlation capturing the higher order sequences with the prograding and aggrading carbonate shelf. Sedimentary facies were identified from electrologs with complete calibration from core description and ECS calibrated ELAN processing results. Gross depositional environment maps were prepared to guide the distribution of primary sedimentary facies within the model for different depositional environments like Slope/Basin, Outer Shelf, Inner Shelf, Shoreface, Barrier/ Shoal, Backbarrier/ Backshore, Lagoon, Tidal Flat, and Sabkha using templates developed for different sequence boundaries.
These carbonates are characterized by seepage reflux dolomitization process and burrows giving rise to enhanced porosity and higher productive layers. This diagenetic imprint was modeled on the primary facies in shoreface and inner shelf areas. This facies model was used to distribute other reservoir properties like porosity, permeability and water saturation using different techniques. The developed model was further calibrated with isotope geochemistry studies and was also validated from comparison with exposed and well studied geological analogue examples. This model showed better predictive capability for wells drilled subsequently.
In this carbonate reservoir, a sequence stratigraphic framework holds the key for distributing the reservoir facies within a 3D geological model in a realistic manner giving better predictability of reservoir properties and facies thereby reducing the field development uncertainty.
A New Approach for the Estimation of a Laterally Variable Anisotropic Velocity Model
Authors: Bacenetti R. , Andreoletti C. , Ferla M. , Panizzardi J. 
Published: March 2015

Abstract
A case history of anisotropic velocity model building on a West Africa (offshore Angola) dataset is proposed. The goal of the project was to improve depth imaging quality, in particular in terms of accuracy of event placement and fault positioning, and also to estimate a reliable velocity model for pore pressure prediction. Seismic data provided evidences of the presence of anisotropy in the area. In order to obtain a robust and reliable estimation of Thomsen's anisotropic parameters, we applied two independent methods in parallel: the first one, used as reference, is based on the standard time-domain approach [1] whilst the second one works in depth domain and applies the migration velocity analysis principles [2]. The two approaches resulted in coherent estimates of Thomsen's parameters but the depth domain approach is preferable because of its integration in the imaging workflow: the definition of the vertical velocity (and, therefore, of Thomsen's delta parameter) at well locations is univocal thanks to the exploitation of depth stratigraphical markers. The introduction of anisotropy in the model, tightly coupled with an accurate velocity analysis, not only allowed obtaining the correct depth positioning but also a remarkable improvement in imaging quality with respect to both PSTM and the initial isotropic PSDM.
Running Casing in Stands with Automate Casing Drive System - Case Studies
Authors: Lee Chee Wai , Won Keith Shao Wang 
Published: March 2015

Abstract
Escalating rig rates in recent years have resulted in operators looking for faster and safer well construction techniques for all aspects, including casing-running operations. With current trends of wells design pushing the casing seat deeper, reduction of total casing-running time plays a crucial role in minimizing total drilling cost. One performance improvement objective is running casing in double-joint or triple-joint stands.
Conventional casing running is known as a high-risk process, involving considerable manual handling on the rig floor. Casing running in stands using the conventional side-door elevators and manual handling by the derrickman on the stabbing board are less efficient and raise safety concerns.
An automated casing-running system has been introduced that can solve the problem of long casing-string handling. This powerful tool minimizes both the rig crew's involvement near the rotary table and personnel working at heights. Casing handling via automation results in a safer casing-running operation and reduces total casing-running time. This versatile system also provides the extra capability of rotating, reciprocating, circulating, and pushing down the casing string through problematic zones to ensure successful installation of the casing at total depth (TD).
This paper will introduce the successful implementation of casing running with double-joint and triple-joint stands using the automated casing-running system, and detail the performance improvements of tripping casing in stands.