bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Shutoff Treatment in Mega Rich Horizontal Well With Coiled Tubing Inflatable Packer for North Caspian
Authors: Burdin K. , Kichigin A. , Mazitov R. , Lobov M. , Bravkov P. , Stepanov V. , Eliseev D. , Zemchihin A. , Byakov A. 
Published: October 2015

Abstract
The Caspian Sea region, which includes Russia, Azerbaijan, Kazakhstan, Turkmenistan, Uzbekistan, and Iran, is one of the oldest oil-producing areas in the world and is an increasingly important source of global energy production. The area has significant oil and natural gas reserves from both offshore deposits in the Caspian Sea itself and onshore fields in the region.
Korchagin oilfield is located in the northern part of the Caspian Sea. Drilled wells are mega-reach (MD/TVD ratio greater than 3.0), with measured depths (MD) up to 23,622 ft and vertical depths of only 5,118 ft. This presents a great challenge for any well interventions, even for Coiled Tubing (CT) equipped with state-of-the-art hydraulic tractors. Limited working area, weight restrictions, challenging well geometry, completion features and lack of experience in offshore CT operations in the North Caspian Sea, required complex pre-job activities to optimize job design, select proper downhole tools and prepare a robust layout plan. This paper illustrates North Caspian project preparation challenges, on-the-job troubleshooting and workflow, supported by the well case studies and results from the first CT operation in North Caspian Offshore. Lessons learnt from the project, where all defined objectives were achieved with zero HSE (health, safety and environment) incidents, were also captured to assist in future campaigns with similar operational environment.
Marginal Commercial Reserves Estimation for Offshore Arctic Projects
Authors: Nagaytsev E. A. , Makarenko A. V. , Ushmaev O. S. , Bochkov A. S. , Varavva A. I. , Samolovov D. A. 
Published: October 2015

Abstract
Arctic offshore development can be characterized relative high capital expenditures for wells drilling, field infrastructure, and often small duration of drilling season. These features restrict ability of oil fields exploration in this region and there is a requirement of comprehensive uncertainty analysis before exploration program is started.
In this work a solution for optimal well spacing calculation for statistically distributed parameters of reservoir is presented. Exponential model of well productivity decline taking into account well lift maximum rate is used for analytical calculation. Using these solutions, it is possible to calculate reserves, NPV and minimal rental reserves distribution. Compared distribution of reserves and minimal rental reserves it is possible to estimate risk of exploration program and prioritize projects.
Waterflood Optimization Principles for Fields with Low-amplitude Tectonic Faults
Authors: Pichugin O. N. , Rodionov S. P. , Solyanoy P. N. , Gavris A. S. , Kosyakov V. P. , Kosheverov G. G. 
Published: October 2015

Abstract
In this paper, the authors demonstrated, using the Nelson criterion, that in case when 50% of cumulative oil production is provided by 5–15% of the wells many fields with terrigenous type of reservoir are characterized by a significant influence of fracturing on reserves recovery. In addition to seismic attributes, the technological performance of wells and logging data were analyzed (the ratio of the actual and estimated flow rates, the frequency of oil rate surge, the ratio of buffer pressure and injectivity, local deviation of OWC, the proportion of active thickness, the quality of cement sheath) which allows to specify the location of the decompression zone. Relation of these characteristics to abnormal well operation was confirmed by the method of statistical hypothesis testing. A high correlation between seismic attributes, which characterize disjunctive faults, and the well performance was observed (oil and liquid rate, water cut), as well as geological structure features (net pay thicknesses, net sand and macro-heterogeneity). Based on the development analysis of one of the fields in Kazakhstan the authors demonstrated a strong dependence between production performance of the area and well placement system, as well as the injectivity of displacing agent in a faulted reservoir. The dependence between the displacement efficiency and injection rate was theoretically confirmed by using the displacement characteristics obtained within this study on the basis of the equation for water saturation in fractured porous media [17]. The fundamental possibility and technological efficiency of waterflood systems transformation based on localization of decompression zones was demonstrated.
Defining Potentially-Productive Intervals and Evaluating Petrophysical Properties of the Tight-Oil Bazhenov Formation in Western Siberia Using a Suite of Modern Wireline Logs
Authors: Melnikov L. , Martinov M. , Demin V. , Cherevko M. , Zaray E. , Ezersky D. , Karpekin E. , Weinheber P. , Filimonov A. , Novikov S. , Blinov V. , Mikhaltseva I. 
Published: October 2015

Abstract
Using advanced logging methods combining NMR and spectroscopy an Oil Saturation Index (OSI) is computed that correlates well with the productive layers of the Bazhenov formation. This article describes a method of estimating the OSI from log data, proposes a model for log interpretation in the Bazhenov Formation sediments and compares the results to core analysis. We present results from three wells.
Features of Gas Well Testing in Reservoir with Low Permeability
Authors: Davletbaev A. Y. , Zhilko E. Y. , Islamov R. R. , Murtazin R. R. , Loznyuk O. A. , Shaybakov R. A. 
Published: October 2015

Abstract
Gas object T is characterized by poor reservoir properties and high horizontal and vertical heterogeneity. Therefore, the development of this reservoir is economically unfeasible with the conventional technologies of production applied to the majority of gas fields in Russia. Besides, by the beginning of the welltests this gas deposit had not been in production.
In order to ensure a deeper assessment of the target reservoir and work out robust engineering decisions, a Target Innovative Project under the title Selection of the development technology for the Turonian low-permeability gas deposit was carried out by Rosneft from 2012 to 2014. Under the pilot project, three different production wells were drilled: a vertical well with a hydraulic fracture (HF), a horizontal well completed with a slot-hole filter, and a horizontal well with a three-stage HF assembly.
This paper discussed the results of field welltests in a low-permeability gas reservoir characterized by high heterogeneity. The welltests were carried out in wells with different completions, estimates were received, and comparison of productivities performed. The paper also discusses the assessment of solid particle sloughing and validates a maximum pressure drawdown for the target reservoir. Pressure-transient tests enabled estimating the permeability of the reservoir, the effective length of the non-HF horizontal well (HW), the parameters of fractures in the vertical HF well and the horizontal three-stage HF well. Effects of nonlinear flow in wells with various completions are considered.
The paper also demonstrates the results of an interference test. This test confirms the existence of hydrodynamic connection between the pilot wells in the target low-permeability gas reservoir.
A Multistage Stimulation Operation to Unlock the Gas Potential of the Turonian Siltstone Formation in Western Siberia
Authors: Loznyuk O. , Surtaev V. , Sakhan A. , Murtazin R. , Latkin K. , Sitdikov S. , Pestrikov A. , Gusakov V. , Politov M. , Yudin A. , Vernigora D. , Olennikova O. , Bulova M. 
Published: October 2015

Abstract
One of the strategic targets in Yamal autonomous district, the Turonian siltstone formation, lies above the Cenomanian formation and is separated by a massive argillite barrier. Successful stimulation experience in vertical wells in the North-Kharampurskoe field during 2008 to 2010 encouraged the operator planning the next step of field exploration to consider horizontal well completions using multistage stimulation. The paper will describe pilot campaign in details.
The Yamal Turonian formation was formed in a coastal marine environment with slow deposition rates and is composed primarily of siltstone. The major challenges of the Turonian formation are low permeability (∼0.5 md) and extremely high clay content—chlorite, kaolinite, illite, and mixed-layer illite-montmorillonite. The low temperature of the Turonian formation (below 80°F) also presents a significant challenge for gas production. An operator must produce at minimum drawdown to avoid hydrates creation. The shallow reservoir depth (∼ 3,000 ft) restricts recovering potential energy stored inside of the formation (initial reservoir pressure of about 1600 psi); therefore, hydraulic fracturing is a must for economic development of the Turonian formation. Selecting the correct fracturing fluid required extensive laboratory tests for compatibility and rheology adjustments. Thorough optimization of the fracturing fluid with clay stabilizer was applied during the course of this project. Additional challenges included proppant flowback tendency and inefficiency of conventional methods (resin-coated proppant) at such low temperatures.
The project began by stimulating a vertical well that was used as a reference for the fracture horizontal well that was stimulated in three stages. Coring and a full logging suite were performed on the reference well, including acoustic measurements, post-frac, to obtain fracture height growth. It was shown that fracture is vertical at such depth and that it covers the whole interval without vertical growth into argillaceous barriers. Bottom hole gauges were used to complete the precise mechanical modeling of the stimulated reference well. Evaluation of the mechanical and properties were completed using E&P software platform-based simulator to optimize the multistage fracturing design in the horizontal well.
This paper includes a detailed sequence of the operations performed and explains conclusions made concerning fracture geometry. The lessons learned during the assessment campaign are described. This stimulation project performed in the North-Kharampurskoe field is fundamental in development of the field and serves as important step toward unlocking the gas potential of other Turonian siltstones.
Possibility of Kerogen Decomposition Using Termo-Gas Wave Stimulation in Bazhenov Formation
Authors: Dieva N. , Dmitriev N. , Kravchenko M. , Muradov A. 
Published: October 2015

Abstract
Significant attention paid recently to development of Bazhen reservoir fields is obviously a result of qualitative leap not only in cognition to geology of such reservoirs, but also a result of so called innovative technologies of O&G fields development of non-conventional hydrocarbons, which includes heavy oil, low permeable reservoirs oil an shale O&G fields. By geological properties, generation conditions and possibilities of development these fields are quite different, but could be combined in common group not only because of huge reserves amount that exceeding conventional hydrocarbon sources, but also by development technologies similarity.
Due to low porosity and permeability of kerogen containing reservoirs, high degree of anisotropy and low percentage of recoverable reserves it is necessary to develop new recovery technologies specially designed for complex and low-permeable reservoirs development. Main target of such methods is structure properties alteration of reservoir and filtration properties improvement of contained fluids. Besides technology should contribute to liquid hydrocarbons generation in source rock. Pilot projects of kerogen-containing Bazhen suite O&G field's development based mostly on chemical, calorific and thermal-chemical methods.
Authors of the article conducted a research of low-permeable reservoirs current development state, analyzed of laboratory experiments and field data of kerogen matrix dissolution with liquid hydrocarbon excretion were also performed. Basing on analysis results mathematical model of kerogen decomposition process in reservoir under thermal-gas-wave influence, representing modern methods of thermal and chemical EOR, was generated. Mathematical modeling research includes a stimulation of inflow to well by injection of chemically-active substances into reservoir for decomposition kerogen conditions.
Multi-Stage Fractured Horizontal Well Numerical Simulation and Its Application in Tight Shale Reservoirs
Authors: Guo Chaohua , Wang Jiaqi , Wei Mingzhen , He Xiaoming , Bai Baojun 
Published: October 2015

Abstract
Unconventional tight shale reservoirs have been developed during recent years due to increasing shortage of conventional resources and a large number of multi-stage fractured horizontal wells (MsFHW) have been drilled to enhance reservoir production performance. Gas flow in tight shale reservoirs is a multi-mechanism process, including: desorption, diffusion, and non-Darcy flow. The productivity of the shale gas reservoir with MsFHW is influenced by both reservoir condition and hydraulic fracture properties. In this paper, a dual-porosity-dual-permeability model was presented to estimate the effect of parameters on shale gas production. Three flow mechanisms have been considered in this model: gas diffusion in nano scale pores, Darcy flow in macro scale pores, and non-Darcy flow in near wellbore hydraulic fractures. Langmuir isotherm was used to simulate the gas desorption process. Hydraulic fractures were performed by Local Grid Refinement (LGR) method.
To conduct sensitivity anlaysis on production performance of tight shale reservoirs with MsFHW, parameters influencing shale gas production were classified into two categories: reservoir properties (including matrix permeability, matrix porosity, natural fracture porosity, rock compressibility, gas desorption) and hydraulic fracture properties (including hydraulic fracture spacing, fracture half-length, fracture conductivity, and fracture height). Typical ranges of these parameters have been reviewed. Sensitivity checks for each parameter were performed to analyze the effect of factors on the cumulative gas production. It can be found that matrix porosity is the most influencing reservoir parameter which has greatest effect on cumulative production among reservoir parameters. And hydraulic fracture spacing, fracture half-length, fracture conductivity, and fracture height are all significant parameters. Result of this study can be used to improve the efficiency of history matching process. Also, it can contribute to the design and optimization of hydraulic fracture treatment design in unconventional tight reservoirs.
Optimization of Cyclic Steam Stimulation (CSS) Under Geomechanics-Dependent Permeability
Authors: Temizel Cenk , Gorucu S. Emre , Erdogan Sinem Setenay , Tiwari Aditya 
Published: October 2015

Abstract

Objectives/Scope:
Since its accidental discovery in Venezuela during a steamflood procedure, and despite the high costs associated with using steam. CSS has been widely used throughout the world in heavy-oil reservoirs, especially in Alberta, California, and Venezuela. It has turned out that it is also important to understand the degree of impact of geomechanics as it is a key parameter in reservoirs with geomechanical response. This makes the optimization process more valuable in terms of the application of crucial operational constraints and parameters, such as injection rate, cycle size, cycle life, and well spacing, not only for the reservoir but also the wellbore, which are important for delivering steam to the subsurface while ensuring minimum heat loss along with reservoir integrity and permeability variation.

Methods, Procedures, Process
The CSS recovery method is influenced by complex reservoir geologies, where a CSS well can penetrate multiple layers having significantly different properties, including permeability. It is important to have a solid understanding of the impact of multiple layers on recovery when using CSS, not only to help maximize recovery but also net-present value because of the high cost of steam generation. In this study, a commercial full-physics reservoir simulator is used to simulate the effect of multiple layers with varying permeabilities under different operating conditions.

Results, Observations, Conclusions
CSS helps to increase recoveries up to 20 to 25% by means of certain mechanisms, including but not limited to viscosity reduction thermal expansion of oil, blocking removal, and gravity drainage. Although it is generally valid that higher steam qualities and shorter soak times provide higher recoveries, the main stages of cyclic steam stimulation (CSS)—injection, soaking, and production—should be carefully optimized because the efficiency of this technique is reduced after the first few cycles. The influence of geomechanics turns out to be a significant parameter in this process.

Novel/Additive Information
The results and sensitivities are compared and discussed in light of a comprehensive literature review of CSS with different process optimization methods, including sequential CSS and cumulative average daily profit methods. The significance of all major parameters are outlined using tornado charts to serve as a practical example for optimization of similar future applications.
Re-fracturing Considerations of Horizontal Well Multi Stage Fractured Completions in Mid Permeability Formations
Authors: Butula K.K. , Yudin A. , Klyubin A. 
Published: October 2015

Abstract
The oil and gas industry in Russia started facing a complex problem of productivity decline from horizontal multi stage fracture completed wells drilled in the low to mid permeability reservoirs. To enhance hydrocarbon flow from these formations, aggressive production using artificial lift is supported with active water flooding. Nevertheless, operators have acknowledged that the horizontal well multi stage fracture (HW MSF) completions do not live to their expectations.
The application of HW MSF completions started in 2008, but widespread acceptance followed several years later. Today, in Russia, about 300 horizontal wells are drilled and completed annually bringing the total number of HW MSF to more than 1200 wells. All these wells are potential candidates for re-fracturing treatments and re-completion, but while re-fracturing of vertical wells is a well proven success in Russia, the industry today has no clear understanding how to address the multitude of potential productivity difficulties in HW MSF.
During the work published in this paper, the team has analyzed all the known potential engineering problems and technical risks and clearly defined the domains of further investigation and set recommendations on measurements that are needed to understand the impact of re-fracturing. The analysis was based on field measurements made, analytical calculation and numerical simulations, modeling in all details the key processes defining the productivity of HW MSF completions. The results indicate that pressure influenced stress changes in a mostly isotropic system and resulting fracture placement within the horizontal wellbore are key contributors to the complexity of the problem.
The paper presented here is a genuine attempt for the industry streamline further search for solutions and novel methodology to effectively re-fracture the existing completion systems and bring these wells to profitable production.
A Novel Automated and Probabilistic EOR Screening Method to Integrate Theoretical Screening Criteria and Real Field EOR Practices Using Machine Learning Algorithms
Authors: Tarrahi Mohammadali , Afra Sardar , Surovets Irina 
Published: October 2015

Abstract
To make promising operational decisions for reservoir exploitation, oil and gas industry relies heavily on predicting the performance of various enhanced recovery processes. Decisions on recovery strategies should be taken in an early stage of field development planning. To select an appropriate recovery technique based on reservoir and fluid characteristics, EOR screening criteria are used as a reliable decision making approach. A dependable first order screening evaluation algorithm enables critical decision making on potential enhanced oil recovery strategies with the limited reservoir information.
In this study, we propose to solve the EOR screening problem by machine learning or pattern recognition methods, which are well-established in computer science literature. We perform a comprehensive study on the application of various machine learning methods such as Bayesian Classifier, K-nearest Neighbor Classifier, Minimum Mean Distance Classifier, and Artificial Neural Networks.
The proposed data-driven screening algorithm is a high-performance tool to select an appropriate EOR method such as steam injection, combustion, miscible injection of CO2 and N2, based on different reservoir and fluid properties such as permeability, depth, API, and viscosity. In this innovative approach, we integrate both theoretical screening principles such as Taber criteria and successful field EOR practices worldwide. Not only this algorithm proposes an appropriate EOR method for a specific reservoir condition but it also gives the probability of success or success rate corresponding to each EOR method. In addition, the proposed algorithm is able to address environmental, economical, geographical and technological limitations.
The proposed algorithm permits integration of different types of data, eliminates arbitrary approach in making decisions, and provides accuracy and fast computation. The suitability of the proposed method is demonstrated by different synthetic and real field EOR cases. This novel EOR screening method is capable of evaluating the effectiveness of different EOR scenarios given a specific reservoir condition. We showed that the proposed EOR screening algorithm is able to predict the appropriate EOR method correctly in more than 90% of cases. We also ranked the proposed screening algorithms based on their screening performance.
Systematic Approach to the Aplication of Chemical EOR in JSC "Rosneft"
Authors: Zakharyan A. G. , Musin R. M. , Cimic M. , Ganiev I. M. , Ismagilov T. A. 
Published: October 2015

Abstract
This article describes a systematic approach used to improve efficiency of water shutoff treatments application in JSC Rosneft. The description of the main stages of this approach as well as n tools and techniques used in it is given.
The approach proposed consists of three main stages. The first stage - the creation of a rating of waterflooding patterns which require application of water shutoff treatments, the second stage - the selection of optimal technologies for a given reservoir properties, which includes an analysis of previous studies, tracer studies, laboratory testing and modeling of the effects of treatments, third stage - monitoring of the operations and probabilistic estimation of incremental oil recovery.