bluuebunny/crossref_metadata_2025 huggingface dataset:
Complex Approach to Well Construction with Cost Minimization in Complicated Mining and Geological Conditions
Authors: Predein Andrey , Klykov Pavel
Published: October 2016

In economically difficult situation in the world including oil and gas industry the question of minimization of costs with use of innovative solutions is actual. Development of hardly removable resources to become possible due to complication of a design of wells and use of the hi-tech equipment. At the same time the question of stability of a well bore is particularly acute more than ever. In this article are provided the results of complex approach to well construction with cost minimization in complicated mining and geological conditions, developed by a Branch of LLC LUKOIL-Engineering "PermNIPIneft" in Perm.
Complex Approach to Drilling Optimization Doubled the Penetration Rates and Eliminated NPT
Authors: Kamatov Kamal , D’Amore Antoine
Published: October 2016

Horizontal drilling and sidetracking of existing wellbores is one of the main methods of production level increase on brownfields. This paper describes the engineering study on drilling performance enhancement conducted for a group of oilfields in Western Siberia, Russia, where the operator company has just started sidetrack and horizontal drilling campaign.

The first several sidetracked wells drilled were characterized by high amounts of non-productive time (NPT) due to downhole tools failures and low penetration rates (ROP). For NPT root cause analysis, drilling surface logging data (including real-time torque and drag analysis) along with downhole measurement while drilling (MWD) vibrations data was analyzed and figured out the failures mechanisms. ROP improvement process included interpretation of LWD and wireline logs and their correlation with bottomhole assembly (BHA) performance via mechanical specific energy (MSE) approach.

A number of factors that led to overall unsatisfactory performance on sidetracks were identified. This included wrong bit selection, limited drilling parameters, hole quality problems and cleaning issues and several others. These issues were properly addressed with field-proven drilling optimization process, which resulted in doubling of previously achieved ROP and elimination of NPT. The next sidetrack was drilled with 40% reduction of average rig days per 1000 m. Based on experienced gained, a motorized rotary steerable system (RSS) BHA was selected for the next complex sidetrack well, and provided another record-breaking performance, with another 20% improvement of ROP. The successful techniques are currently being transferred from sidetracks to horizontal sections on new wellbores.

The paper represents latest achievements of ongoing drilling optimization process, which allowed the operator company to significantly decrease time and operational costs on drilling operations. The described complex geological and technological approach, along with revised wellbore placement, have led to main project performance indicators increase and next-step completion and production solutions for enhanced hydrocarbons recovery.
Drill Bit Evolution During Execution of Long-Term Offshore ERD Project
Authors: Bebeshko Ivan , Kazurov Andrey , Ruzhnikov Alexey , Zhentichka Maxim , Kuznetsov Alexander , Petrova Galina , Zvyagin Vasiliy
Published: October 2016

Initial selection and further optimization of drill bits is one of the key factors of an effective drilling process, which is particularly important in high-cost projects. This article presents the incremental changes made to increase the ROP and mechanical efficiency of drill bits while drilling offshore extended-reach drilling (ERD) wells.

With the implementation of the tasks based on a well-by-well analysis of bits, recommendations were developed for optimizing the design of drill bits. These recommendations were based on results of bit simulations in specialized software with correlation of proposed models and actual results. Simultaneous bit optimization was performed in conjunction with other elements of the BHA with the help of an integrated engineering analysis system. The result was the development of new bit designs and sizes designed for drilling specific rock in specific fields.

In addition to the optimization of the drill bits themselves, a refined technological component was introduced: a real-time drillbit optimization system to enhance ROP, decrease bit wear while drilling, and ensure maximum run length via the optimization of drilling parameters.

Application of the proposed technical and technological changes has increased ROP up to two times, and enabled a bit to drill a 4,900-m section in one run with minimum bit wear, leading to a reduction in the cost of the well.

As a result, bits for ERD were optimized for each size, and a drilling parameters map was created. This map was updated based on the result of the construction of each well to ensure maximum efficiency with minimal bit wear during subsequent drilling.

Additionally, one of the most important results was a 6-year record of no NPT associated with the drill bits.

Experience gathered during the development of the bits using advanced modeling applications, together with real-time drilling optimization, will be applied on a nearby offshore field to minimize the time required to reach the optimal ROP.

This article describes the selection, optimization, and continuous improvement of drill bits using the latest techniques and technologies, the use of which occurred gradually during development over several years. The above approaches can be applied to ERD and standard horizontal wells worldwide.
Experimental Study on the Effect of Spiral Flow on Wax Deposition Thickness
Authors: Theyab Muhammad Ali , Diaz Pedro
Published: October 2016

Wax precipitation is one of the most important flow assurance problems, and a significant economic issue in the petroleum industry. Wax leading to increase fluid viscosity causing the blockage of filters, valves and even pipelines, increasing pumping costs, and reducing or even stopping oil production or transport. Wax can precipitate as a solid phase on the pipe wall when its temperature drops below the Wax Appearance Temperature (WAT).

The objective of this study is using spiral flow to mitigate wax deposition. An experimental flow loop system was built in the lab to study the variation of wax deposition thickness under the single phase transport. A series of experiments were carried out at different flow rates (2.7 and 4.8 L/min) to study wax deposition process and measure the wax thickness. The effects of factors on wax formation, such as spiral flow, inlet coolant temperature, temperature drop, flow rates and experimental time have been examined.

The spiral flow created inside the pipe by inserting a twisted metal along the pipe, which will create high shear stress affecting to wax deposition. The results show that the wax inhibition (reduction) percentage (WI) % by using the spiral flow at flow rate 2.7 L/min, inlet coolant temperature14 °C, was 65%. At flow rate 4.8 L/min, inlet coolant temperature 14 °C the wax inhibition percentage was 73%. Experimentally, it was found that the spiral flow more efficient than the chemical inhibitors. This percentage of reduction will increase rapidly by increasing the inlet coolant temperature and decreased by reducing the inlet coolant temperature.

This technique of creating spiral flow inside the test section of the pipe will provide a step forward in flow assurance technology to mitigate the deposition of wax.
Low-Volume Positive Displacement Pumps For Production of Viscous Fluids
Authors: Panachev Mikhail
Published: October 2016

A submersible system is provided for viscous fluids recovery making use of a newly designed rotary displacement sliding-vane pump. As opposed to sucker rod and surface-driven PCP pumps also used for viscous oil extraction, the system in question does not include elastomers (requiring selectin to match the fluid being extracted) and forgoes the line of rods, hence there are no limitations for lift it generates and it could be deployed even in horizontal wells.

The first sample has been in operation for almost a year with average flow about 10 m3/day and reservoir conditions of 70 CP.
Pore Structure of West Siberian Jurassic Clastic Reservoirs: Detailed Evaluation with Use of New Generation Wireline Technologies
Authors: Delia S. V. , Drandusov K. A. , Ezersky D. M. , Novikov S. V. , Weinheber P. , Vasilyev D. V. , Filimonov A. Y.
Published: October 2016

Highly heterogeneous rocks are known to provide significant challenges for the determination of permeability and other reservoir properties. Carbonates are known to be micro heterogeneous as well as macro laterally heterogeneous. However, the problem of accounting the structure of the pore space geometry is highly relevant in low-permeability shaly-sand rocks. Traditionally this problem is solved with extensive core analysis. In this article we present alternate methods with advanced logging tools and interpretation techniques to address the challenges.
Interference Test in Naturally Fractured Formation Gas Field Case Study
Authors: Vasilev I. , Aleksakhin Y.
Published: October 2016

Naturally fractured reservoirs present a production paradox. It is not an exaggeration to say that the big part of the world oil and gas reserves are concentrated in naturally fractured reservoirs (NFR). Naturally fractured formations may have different genesis. Igneous, metamorphic and sedimentary rocks undergo of fracturing and faulting as well while forming extensive and narrow system of highly conductive zones.

In this paper, we investigate and analyze core study results, interference test results conducted in naturally fractured formation on gas field, draw conclusions about the conducted test and analyze interpretation results.

At the end of this paper, we give recommendations for using the test for determinations of high permeable zone in naturally fractured reservoir.
Fracture Quantitative Characterization Using Tracer Flowback for Multistage Fracturing Horizontal Well in Tight Oil
Authors: Li Linkai , Jiang Hanqiao , Li Junjian , Zhao Lijun
Published: October 2016

Unconventional reservoirs have emerged as significant hydrocarbon supplies all over the world. Although horizontal drilling combined with multistage hydraulic-fracturing techniques has enabled commercial hydrocarbon production from unconventional reservoirs, fracture characterization in such complex reservoirs remains challenging. In this study, we propose an analytical model to characterize fracture using the early-time post-stimulation tracer flowback profile.

The tracer flowback analysis is a quick method used to evaluate load recovery of hydraulic liquids, productivity of each stage and fracture characterization. However, tracer flowback analysis combined with microseismic data is still at qualitative appraisal stage and non-Newtonian effect of hydraulic fluids is not considered. Therefore, based on convection-diffusion transport theory, a tracer injection flowback model is developed and solved by Laplace transform and image reflection method, and then fracture parameters characterization is proposed considering the non-Newtonian hydraulic fluids flow.

The results demonstrate that the calculated tracer profile of the presented model can well explain the main part of tracer flowback profile except the long trail. That is because the model only considers the process of tracer transports in hydraulic fractures while the long tail of tracer flowback profile reflects the mass interchange between hydraulic fractures and tight matrix. Parameters sensitivity study shows that the peak of tracer flowback profile decrease with the increasing dispersion coefficient and retardation; tracer dispersion induces the increment of tracer slug extent. The differernce of tracer injection and flowback rate severly affects the shape of tracer flowback profile. Fracture parameters are characterized and validated with field data.

The presented model for describing the behavior the tracer profile during the flow back process provides an alternative approach for reservoir characterization. This study encourages the industry to manage the flowback operations carefully.
Investigation of Optical and Rheological Properties of Natural and Recombined Hydrocarbon Mixtures
Authors: Ramis Burkhanov , Ildar Ibragimov , Mars Khannanov , Azat Lutfullin
Published: October 2016

Currently, oil companies are actively using dual completion and production systems (DCPS/DS). In the case of using this technique fluids of two formations are mixed in the wellbore. Two formations are being operated simultaneously by one well. For better control on the oil recovery from both the formations a reliable and prompt product sharing technique is necessary nowadays. Rheological and optical properties of natural and recombined hydrocarbon mixtures have been investigated whithin the research. Recombined mixtures have been produced by mixing oil samples of different reservoirs. These studies are aimed at solving inverse problems, i.e. for product sharing problem.
Quantitative Inflow Profile Determination in Unsable Producers Transient Temperature Potential
Authors: Panarina E. P. , Kremenetskiy M. I. , Melnikov S. I.
Published: October 2016

A difficult condition of field development requires the search for new methods and techniques for more comercial production. There is active development and introduction of new technologies in the field of geophysical monitoring technologies in recent years. When the well inflow is a multi-phase one, or is low and unstable, the flow metering data tends to be of no particular value for evaluation of pay potential of a formation. Thus, some alternative evaluation methods become increasingly required. According to field data analysis, temperature log appears to be the most efficient geophysical survey in a setting discussed.

The report looks into capabilities of temperature log and the scope of its applicability to quantitative evaluation of production from formations that are only able to provide some low and unstable multi-phase inflow. The report describes the method of evaluating well production outside inflow intervals in case of a cycling operating pattern or when the well operating mode is changed, and thus geothermal temperature distribution can not be used as background data.

Examples include well test results obtained on fields of different types (terrigenous, carbonate) with different saturation of reservoirs when they were opened by a vertical well and by a horizontal well.
Multi-Zone Waterflood Top Seal Integrity Assurance: Insights from Advanced Pressure Fall Off Analysis Using Smart Well and DTS Technologies Offshore Sakhalin, Russia
Authors: Petrik Artyom , van den Hoek Paul
Published: October 2016

Assuring the topseal integrity during waterflood is important for petroleum field development. Several cases of failure to do so in the industry worldwide resulted in severe reservoir management and environmental problems, when either unwanted inter-zone communication, or even break all way up to the seafloor occurred.

Case history of applying topseal integrity assurance process with novel controlling approach in a stacked multi-reservoir environment, offshore field, is described in the article.

Approach applied within Sakhalin Energy includes definition of safe operating envelopes for water injection (injection rates, pressures, water quality), based on appropriate reservoir data collection, injection fracture propagation modelling, followed by model calibration and actual fracture height assessment with distributed temperature sensors. Multi-zone smart completions are being used to make zone-by-zone dedicated fracture calibration tests. Then, a proprietary technique to assess actual geometries of injection-induced fractures is applied for control.

The complete process to ensure topseal integrity assurance was developed and applied at the multi-reservoir oilfield offshore Sakhalin, Russia. Practical steps including unsuccessful initial trials with the lessons learnt analysis, and proven working algorithm are described. Based on the results, a simplified, cost-effective yet robust and fit for purpose topseal integrity assurance process is developed and field tested in an offshore multi-zone environment, applicable also to single zone wells and onshore.

A novel method of injection–induced fracture geometries determination from pressure falloff analysis in a smart well completion in a multi-zone well was applied for the first time in the industry, number of other steps were innovations in Russia or/and offshore environment.

Case history provides a practical approach to topseal integrity assurance proven to work and applicable elsewhere, as well as the lessons learnt and adjustments made based on experience.
Waterflooding Optimization in Case of Auto-Frac Naturally Fractured Reservoir
Authors: Maksimovskiy I. V. , Akimov A. G. , Yamaletdinov A. F. , Zhilina M. A.
Published: October 2016

The studied object is a part of a large field of the Uvat region (Western Siberia). The development process of the oil formation is conducted applying the waterflooding system. It is complicated by naturally fractured carbonate member and generation of auto-fractures at injection wells. The advancing rated of watercut and premature water breakthrough toward the production wells are observed. The studied reservoir has a complex geology, lithological intersection consists of clastic and carbonate members. Waterflooding system is not optimized: reservoir pressure falls and auto-fracs occur due to high repressions, that causes increase of watercut at production wells. Great amount of oil reserves is not withdrawn according to prevailing proceses. In this case, it was necessary to determine the reasons of noneffective development strategy and to optimize waterflooding system.

The algorithm for searching of a decision for optimization of reservoir development in case of auto-fracs generation is formed in this paper. The sequence of analysis and valid analytical methods for reasons determination of advancing watercut are defined during the work.

Complex analysis of geology, reservoir engineering, well testing and reservoir simulation forms the basis of the applied algorithm:

Analytical methods of advancing watercut determination are used during reservoir development analysis. As a result, the reasons of premature water breakthrough toward the production wells and volume of undrained oil reserves became obvious.

During the geology analysis main facies and features of the occurrence and spread are defined; created a distribution map of "superpermeable" facies. As a result, the map of wells interference is generated, in which zones of noneffective waterflooding and degree of reserves involvement in production are determined.

The presence of auto-fracs at injection wells is identified according to the well test analysis. As a result, dependency of auto-fracture generation pressure from injection rates and reservoir pressure is determine. Understanding of this dependency allowed to optimize technological regims of injection wells. Also, dual-porosity parameters of naturally fractured member are determined from these tests, after that simulation reservoir model was adjusted.

Because of the comprehensive analysis and understanding of all processes the large number of scenarios for reservoir development optimization appeared. To reduce the labor-intensive calculations and culling options the analytical model and the algorithm for choosing the best solution was formed. According to the algorithm several options were selected for more detailed calculation with reservoir simulation model.
Inflow Monitoring and Analysis Using Proprietary Intelligent Chemical Tracers in the Yuri Korchagina Field
Authors: Shtun S. , Senkov A. , Surmaev A.
Published: October 2016

The first installation of intelligent tracers system in extended reach horizontal well was deployed by LUKOIL-Nizhnevolzhskneft LLC in a thin oil rim reservoir with a large gas cap located in the North region of the Caspian sea. Putting in operation of the Yu. Korchagin field is challenging serious tasks during development:relative zone inflow estimation;identifying intervals of water breakthrough;long-term monitoring of oil extraction and water level;monitoring of completion equipment functionality.

Traditional technologies of production logging, considering complex well trajectory, are highly risky and expensive.

Fiber-optic system of monitoring of Distributed Temperature Sensors (DTS) would be an ideal instrument identifying the source of gas breakthrough, but such technology is not always feasible due to necessity of rotation of the completion during its running in extended reach horizontal well. Performance of periodic field research via cable is limited due to drilling operations on the platform. In addition to perform such survey it is required to use downhole tractors to transport logging tool. Practice of tractors usage in extended horizontal wells in the field has a negative statistics to reach the toe of the well, as for a project operator it's important to verify remote flow contribution (e.g. 7000 m) in total well flow rate.

To solve the above problem a relatively new monitoring technology has been applied.

At stage of equipment fabrication downhole intelligent chemical sensors were installed in sand screens. Sensors are placed in the drainage area in different intervals along the well to meet objectives by the engineers of LUKOIL Nizhnevolzhskneft LLC to provide flow profiles, identify the location of gas breakthrough and confirmation of the functional work of AICD in the course of time.

After selection of surface samples of hydrocarbons at the wellhead, a laboratory analysis is conducted for chemical tracers in the sample and interpretation of tracer signals during unsteady and steady state production is performed. Some period has passed related to operation of the well after its start. The first well equipped with intelligent chemical indicators has its history of production; the well performance can be evaluated both in whole, and for each zone equipped with chemical indicators.

This paper will review the experience of wireless monitoring for extend horizontal well on the shelf of the Caspian sea.
Problems of Modern Multiphase Flow Measurement: Properties of Two-Velocity, Water-Oil Mix Flows in the Presence of Surfactants
Authors: Dorovsky Vitaly , Perepechko Yury
Published: October 2016

Production logging encompasses profiling of flow velocities, holdup, pressure and temperature along the length of a horizontal well. Its advancement is determined by such factors as mathematical modeling, and development of new tools and software. These activities generalize the understanding of the multiphase flow meter, which requires a proper mathematical tool to calculate the parameters of multiphase flow. The natural water-oil flow always contains surfactants. The substances adsorbed on the surface of oil droplets affect the dynamics of the immiscible fluids; therefore, proper analysis of this effect is particularly important.

The paper presents the theory of two-velocity hydrodynamic continuum taking into account the surfactant effect to analyze the flow regimes of a two-phase system and develop the hydrodynamic grounds generalizing the understanding of the multiphase flow meter. Its two-velocity equations are derived only from the main physical laws. The equations are true for an arbitrary class of the state equations. Its difference scheme is based on the control volume method. The effect of a phase interaction force was demonstrated on the two-phase flow regimes, which is essential for accurate holdup measurements in modern hydrodynamic logging. The theory shows that the surface-tension gradient in a two-phase flow produces an additional drag force. The force is significant and can exceed both the viscous and Stokes friction forces. The theory demonstrates that, in a two-velocity medium, in the presence of surfactants, an additional reactive force is observed that is proportional to the gradient of the surfactant dissolved in water. In this case, the hydrodynamic velocity determines the surfactant spatial concentration. The gradient produces the reactive forces in moving subsystems that affect the rate of hydrodynamic transport. The interaction results in a consistent velocity profile of both water and oil. Having slowed the motion of oil, the surfactant increases the velocity of the water. At the relatively low velocities, the surfactant effects on the phase velocities, which is important for determining the holdups of phases in the cross-sections of production wells.
Compositional Simulator with Non-equilibrium Phase Transitions
Authors: Zubov V. R. , Indrupskiy I. M. , Bogachev K. Yu.
Published: October 2016

The paper presents efficient implementation of the non-equilibrium phase transitions model in compositional simulator. Reservoir non-equilibrium phase behavior effects are examined and simulated with the new approach.

Compositional simulators are widely used for modeling light oil reservoirs, gas injection projects, and gas-condensate reservoirs. Some features for modeling phase transition hysteresis are implemented in black oil simulators, but not in compositional simulators. Though some non-equilibrium phase transition models for compositional simulators were reported in the literature, they were not implemented in industrial simulators because of their complexity. A new physical-based approach is presented in this paper. Modifications for this model are required only to the thermodynamic block of a simulator. All equations and matrix structures for the hydrodynamic (flow) block are not modified.

The new approach is implemented as an extension block in a general purpose reservoir simulator. Implementation of the feature allows to model effects of phase transition hysteresis in compositional simulations. Criterion for determining phase transition type (equilibrium or non-equilibrium) is justified and also implemented.

The application of the new option requires minimum additional input data, which is good for history matching problems. The new approach is tested with numerical cases based on real reservoir data.
Peculiarities of Lihology and Petrophysical Parameters Calculation and Transfer from Epilogs to 3D Geomodel
Authors: Kolbikov Sergey
Published: October 2016

The method of averaging epilog parameters into the cell of 3D grid depends on the type of parameters and vertical cell size. The objective is to improve methods of calculating and transferring epilogs into the 3D grid of geological model. The paper presents the typical mistakes made by designers while reservoir parameters transfer into the 3D grid of geological and hydrodynamic models. The method of pseudo anisotropy factor (Kv / Kh) calculation from well epilogs had been proposed.

The model loses connectivity of the reservoir and understated HCIP when it cells are resulting to non-reservoir ones due to sufficiently high cutoff value of net-to-gross (up to 0.5) for the lithology parameter (reservoir / non-reservoir). To compensate for such imbalance reservoir engineers often neglect the NTG value for reservoir cells, calculating epilog parameters only for the reservoir intervals. Reducing the value for the NTG cutoff down to 0.1-0.2 and the introduction of NTG values for all reservoir cells allows more accurately reproduce the hydrodynamic connectivity of the model and the HCIP distribution.

It is shown that if the value of permeability in the reservoir cell of 3D grid calculate through the mean porosity for all epilog intervals of the cell, then the permeability value will correspond to the geometric mean, and will characterize the vertical permeability. To obtain a correct value for the lateral permeability of the cell it is necessary to calculate it as an arithmetic mean value for all reservoir intervals of the epilog within this cell. The ratio of vertical and lateral permeability will give us the value for the pseudo anisotropy of the cell. Guidelines for calculation and transfer of the epilogs into 3D grid shown in the work will result in the correct initial distribution of the lateral and vertical permeability in the geological and hydrodynamic models, differentiated values for the pseudo anisotropy factors of cells.

For the cases of geological models construction with hydrodynamic grid dimensions the upscaling is performed while transferring well epilogs into the 3D geological grid. The proposed method allows more correct averaging for the initial permeability distribution and calculate the vertical anisotropy for the reservoir cells as a function of their heterogeneity.
Thermal Simulation with Multilateral Wells
Authors: Bogachev K. , Tran H. , Milyutin S. , Sorokina M.
Published: October 2016

In this study we investigated full-field fine-scaled thermal reservoir models with multilateral wells that are independent of grid refinements and thus allow efficient optimization of well placements. This facilitated the production optimization and well interference study in thermal modeling framework. We observed that multilateral wells with multiple sidetracks enhanced the steam injection efficiency by enlarging steam chambers. We also examined the benefit of utilizing high performance computing (HPC) in multiple-node cluster environments. Results showed that excellent scalability was achieved with up to thousands of computing CPUs and total simulation time was reduced from weeks to hours. More importantly, the study confirmed that in thermal simulation coarser grid models overestimate steam chambers leading to overestimating total field production and reserves.
Integrated Modeling as a Tool for Evaluating the Effects of Well Production Rates and Surface Gathering System Performance on Development of Oil Rim
Authors: Ushmaev O. S. , Apasov R. T. , Chameyev I. L. , Mozhchil A. F. , Tkachuk A. V. , Kurochkin M.S. , Bolshakova A. A. , Vernus J. C. , Bayguzov R. A. , Maskaev P. S.
Published: October 2016

Efficient development of oil rims requires tools for making production forecasts to consider not only in situ processes, but also limitations of surface infrastructure.

This paper describes a case study of creating an integrated structural model of field X containing a block with 30 wells confined to an area of about 20 million m2.

Oil accumulations in this field are represented by marginal and underlying oil rims.

The basic concept of oil rim development in the field is re-injection of the produced associated gas back into the reservoir. Volumes of gas injected to maintain reservoir pressure affect oil production levels. Conversely, efficient oil well operation depends on associated gas production, including the gas breaking through from gas caps. With this development strategy, it is critical to consider the limitations of artificial lift systems, production gathering, and treatment systems to maximize economic performance of the project and to generate reliable oil, gas, and water production forecasts.

Integrated modeling is aimed at a detailed approach of predicting production levels by combining the reservoir, well, and surface gathering systems into a single generalized model. Such model should account for processes taking place in both the reservoir and surface gathering systems, as well as limitations such as gas and fluid velocities in well lifting and gathering network systems, design limitations of gas and oil treatment facilities, and pipeline loops and jumpers, with the final objective of improving the quality of decision-making.

The paper describes the basic steps of building an integrated model and the results of comparing production forecasts based on a conventional hydrodynamic model with those based on an integrated model. Calculations proved that well interventions are required for a more efficient field development to optimize production rates from the producing wells.
A Case Study of the Application of Geostatistical Inversion for Building a Three-Dimensional Geological Model of One of Uvat Reservoirs
Authors: Khamitullin I. M. , Novokreschin A. V. , Shilova Y. V. , Chernovets L. V. , Nikitin A. Yu.
Published: October 2016

This article describes the technology and results of geostatistical inversion for predicting reservoir properties of J3 reservoir in order to build a 3D geological model. It also describes the geological and geophysical data required to perform the geostatistical inversion including the quantitative and qualitative characteristics.

In the studied field, the main oil exploration target is associated with J3 reservoir. The complex structure of the reservoir is explained by the sharp facies variability common for continental depositional environments. Many equally possible realizations from the results of geostatistical inversion and their high resolution helped to reduce uncertainties and to refine the geological structure of the field. The reliability of the results is confirmed by a "blind" well which was drilled in the process of geostatistical inversion.
Advanced Modeling of a Field Pilot Program
Authors: Shigapova D. Yu. , Surnachev D.V. , Ryabov A.N.
Published: October 2016

In the manuscript the main idea is to tell about detailed 3D modeling as a good way to provide optimal plan of field pilot program (FPP) and to increase the value and reliability of the obtained information. It has to be noted that in this work will be detailed considered a process of the well test planning and design of horizontal wells, as one of the most important sources of information about the formation with limited time and / or production from the reservoir. Recommendations for modeling well tests using the geological and hydrodynamic model to account for the three-dimensional reservoir heterogeneity are provided.

It will be described about examples of work with an area of FPP at the field, which is situated in Arctic conditions. The authors believe that a similar approach can be greatly helpful in the planning of activities for offshore fields.

The main advantages of using detailed simulations during the planning and implementation of a field pilot program are:–Assessing the necessary and sufficient research in respect of the volume of fluid, the duration of holding time, revenue response, etc. taking into account the three-dimensional geological heterogeneity of the reservoir;–Keeping technology infrastructure constraints;–Formation of metrology hardware requirements;–The ability to quickly, in the process of implementation to adjust the plan and design activities and/or researches with the obtained information;–Communication and scalability well test results to the entire reservoir/field.
Geomechanics Based Completion Strategy Optimization for the Chemical Interaction Effect with Mechanical Properties
Authors: Smirnov N , Torres Martin Sigifredo , Valente Livan Blanco , Tadzhibayev Rustam , Vladimirovich Molodtsov Roman , Vitalievich Kuznetsov Igor , Pavlovich Khomenok Ivan
Published: October 2016

Wells with high strength carbonate reservoir formation generally practice open hole completion strategy. It allows to substantially reduce expenditures and risks associated with well construction. At the same time, borehole stability during well's exploitation depends on strength properties on the one hand, and stresses which rocks are withstanding during production on the other. In its turn stresses depend on many factors, related with geological aspects and are controlled by drawdown pressure applied to reservoir. Nowadays all main components for well stability can be identified with logging data, core information and software tools for modeling and computation.

In order to improve reservoir quality, quite often a near wellbore area is treated with different chemical agents and compositions. Unfortunately, a few people bear in mind, that after the chemical reaction rock might overcome significant changes as it weakens and deforms. This paper describes practical application of geomechanical modeling with Mechanical Earth Model construction [2] and reservoir stability evaluation of horizontal well section with the open hole completion before and after acid treatment with different depressions. [1].

In order to determine petrophysical and mechanical properties changes before and after acidizing, mechanical tests were conducted on the core samples from Bashkirian horizon. Results were used as a basis for justification and open hole completion optimization strategy.
Experience in 3D Geomechanical Modeling, Based on One of the West Siberia Oilfield
Authors: Ovcharenko Y. , Lukin S. , Tatur O. , Kalinin O. , Kolesnikov D. , Esipov S. , Zhukov V. , Demin V. , Volokitin Y. , Sednev A. , Podberezny M.
Published: October 2016

Work is devoted to construction 3D Geomechanics model for Achimov Formation for one of the West Siberia oilfield. The model is performed for monitoring and control field throughout the cycle of its life – start from drilling process (recommendation for optimization well trajectory and well design to exclude drilling risks) and during oilfield development (monitoring the development process to take account of changes in the stress state of the oilfield, its influence on the hydraulic fracture growth and hydrocarbon production processes). Oilfield, which are currently introduced in the development, characterize by increasingly complex geology and, consequently, require more sophisticated technological solutions for both the construction of wells and the development process, which involves the need to build complex 3D geological and geomechanical models.

As a result of the work was calculated current stress state on the field, taking into account the effects of faults. Special attention was paid to the process of mapping of faults and low-amplitude tectonic dislocation. For this purpose used inversion stress model, including simulation of deformations and displacements arising under the action of tectonic driver. This model allows to select the tectonic dislocation, the scale of which is significantly smaller than the resolution of seismic.

Based on the results of the verification of geomechanical model and sensitivity analysis to the source data, formulated the basic methodological approaches for building and testing models of geomechanical properties was done. During the work was made a forecast borehole stability for horizontal wells, create a map of faults, found the relationship between the faults parameters and their impact on the stress changes in the area of interest, assessed the impact of changes in reservoir pressure during field development on the stress orientation, predicted direction of hydraulic fracture and formed recommendations on hydraulic fracturing design taking into account possible variations in the stress state of the sector of modeling.
Experience of 20 Plus Stage Fracture Stimulation in Samotlorskoye Field
Authors: Kudrya Semen , Baydyukov Konstantin , Samoilov Mikhail
Published: October 2016

In 2009, OJSC "Samotlorneftegas" began performing two-stage fracture stimulations in newly drilled and sidetracked wells. The wells were treated zone-by-zone, with frac fleets doing two or more frac jobs. Slotted filter intervals were treated first. Then they were plugged off with bridge plugs or proppant for the next interval to treat. After two frac jobs, the bottom-holes were cleaned and the wells were started.

The success of the method consisted in an increased oil production at an early stage of production (around 40 tons per day from newly drilled wells) and in a slower decline in flow rates throughout the first year of production (around 35%) as compared to directional wells. There was only one disadvantage - a longer shut-in period (up to 60 days), which, with low formation pressures, can lead to a lower oil increment due to saturation of the formations with flush fluids.

In mid 2011, the multistage stimulation technologies did not find improvement for a number of reasons: No multistage fracturing equipment on the market. No such equipment was built in Russia and oil companies showed little interest in a large-scale application of purpose-built multistage fracturing completion systems;Lack of multistage fracturing experience;Significant geological and technological risks involved, when using these technologies to improve production to expected levels and enhance the cost effectiveness of these projects;Little experience in horizontal drilling with the drilling conditions being difficult to make large enough holes to accommodate multistage fracturing systems (MSFS). No effective annular isolation techniques.

In the first half of 2011, special ball-activated sleeves were delivered to the Russian market from abroad. However, OJSC "Samotlorneftegas" continued using an interesting multistage fracturing technique employing the use of burst port collars and cup-to-cup (C2C) tools.

The technology was being improved for 4 years. Owing to the improvement efforts, a unique 29-stage frac job was performed at the beginning of 2016.
Intensification of Oil Production Based on Invert-Emulsion with SiO2 Nanoparticles and Gelled Acid
Authors: Sergeev V. , Foundation Skolkovo , Imangaliyev B. , Ayupov R.
Published: October 2016

Results of Pashninsky oilfield wells operation monitoring after complex intensification of oil production (IOP) technology treatment are presented in article. The analysis of monitoring results of IOP technology's disadvantage was determined and ways of improvement of the technology were proposed. Based on results of laboratory research the most effective gelling agents for hydrochloric acid composition were proposed. Based on invert-emulsion (IES) new water-blocking solution with SiO2 nanoparticles content was developed. On results of interaction seven different gelling agents with hydrochloric acid composition by chemical laboratory tests have found that the most effective gelling agents are based on cocamide DEA (diethanolamide) agent that enable to reach viscosity by a factor of 3-8 to basic acid composition viscosity. Results of experiments on interactions of invert-emulsion solution with SiO2 nanoparticles content identified that nanoparticles presence into IES assist to structure stability and dynamic viscosity growth up to 800-1500 mPa·s.
Effect of Horizontal Wells Location on Steam Assisted Gravity Drainage Technology Efficiency
Authors: Amerkhanov Marat , Zaripov Azat , Shaikhutdinov Damir
Published: October 2016

Pilot extra-heavy oil production project in Tatarstan has demonstrated the effectiveness of steam stimulation technologies and horizontal drilling. The paper discusses approaches to increase the effectiveness of the steam-assisted gravity drainage (SAGD) process based on the results of in-depth study of geological aspects that contribute to well performance. Different scenarios of horizontal well placement have been analyzed. Criteria for optimal placement of horizontal wells in terms of geological conditions have been worked out. It has been found that on the one hand, the closer the horizontal well to the water-oil contact (WOC), the higher the final oil recovery factor, but, on the other hand, it takes a longer period to bring the well on to sustained production. The farther the horizontal well to WOC, the higher the effectiveness of the SAGD process, but the final oil recovery factor is lower, which is critical for heavy oil accumulations with relatively low OOIP in Tatarstan.
Mechanisms of Thermal-Pressure Induced Impact of Binary Mixture Reaction Near Wellbore
Authors: Vershinin V. , Fedorov K. , Lishchuk A.
Published: October 2016

The paper considers mechanisms of well production increase by applying thermal-gas-chemical impact or liquid explosive injection in a pay zone. We have introduced the computing model for thermal-gas-chemical impact process for thoroughly investigation of different contribution on well post production. Numerical calculations of thermal effects on formation heating of particular well during thermal-gas-chemical impact showed that utilized explosive slug simply cannot cause actual increase of production rates and observed effect duration. Then we analyzed the contribution of pay zone cleaning from asphaltene, tar and paraffin precipitations. And finally the mechanism of micro fractures network formation was discussed. Assessments of required explosive concentrations and microfracturing parameters in thermal-gas-chemical impact were performed.
Problems of Gas Condensate Field Production Solved by Novel Enlarged Block Simulator
Authors: Vershinin Vladimir Evgenyevich , Grigoryev Andrey Viktorovich , Fedorov Konstantin Mikhaylovich
Published: October 2016

The paper considers methods of gas and condensate production increase by choosing optimal well production parameters. The existing methods might become overcomplicated and require special optimization process for large amount.

To describe the well production parameters we have chosen the nodal model for the system: formation-well-flow line with specific closing relations. The optimization problem was formulated for the chosen nodal model but it requires a lot of calculations.

We have developed the solution algorithm where the task is discredited namely the subtasks that allow us to use dynamic programming and reduce calculations.

The solution of practical objective was taken as an example to maximize condensate production in the gas and condensate field.
Development Strategy Optimization and Application for Fractured-Vuggy Carbonate Gas Condensate Reservoirs
Authors: Yong Li , Baozhu Li , Jing Xia , Xuelei Zhang , Xingliang Deng , Zhicheng She , Zhiliang Liu
Published: October 2016

Naturally fractured-vuggy carbonate gas condensate reservoirs in China have some distinctive characteristics: deep buried depth, multi-scale fractures, vugs and caves developed, poor reservoir connectivity, high production decline rate and low estimated ultimate recovery. So how to properly develop this kind of reservoirs is a major challenge. This paper presents the study on development strategy optimization for fractured-vuggy carbonate gas condensate reservoirs in detail.

Based on the geological survey of palaeokarst outcrops and seismic interpretation, representative reservoir type patterns of fractured-vuggy carbonate gas condensate reservoirs can be determined. And combined geological study and dynamic characterization, different reservoir patterns can be identified and characterized. After that, simulation models of different reservoir patterns are built, in order to study the detailed development strategy on primary depletion and water flooding huff-and-puff. And optimal development strategies are applied into the TZ fractured-vuggy carbonate gas condensate reservoir in China.

Take TZ carbonate gas condensate reservoir in China for example. The mid-depth of TZ reservoir is 5500m with annual production decline rate higher than 25%. Through geological and dynamic characterization, six representative reservoir type patterns are identified and characterized. And more than half drilled patterns in TZ are isolated and developed in very limited volume, which only need one well to develop each pattern. Then reservoir simulation models of the six patterns are built to investigate the optimized development strategies. The results show vertical wells are optimum for four patterns and horizontal wells are optimum for two patterns. For isolated karst caves pattern, there are still lots of remaining condensate oil after primary depletion, so water injection huff-and-puff are studied for this pattern. The results are applied to TZ reservoir.

This paper offers a case study on development strategy optimization of different reservoir patterns for fractured-caved gas condensate carbonate reservoirs, and the understandings are successfully applied to TZ carbonate gas condensate reservoir. It also provides a methodology and an improved oil recovery reference case for engineers and geologists to develop other similar reservoirs.