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After hydraulic fracturing treatment, wellbore clean-out takes significant amount of time, and therefore, the commissioning of the well is delayed. In addition to production losses, production companies CAPEX and OPEX are also increasing proportionally to frac fleet activity. As a common practice, in western Siberia fracturing treatment is underflushed by about 0.5 cubic meters. This is supposed to prevent unintentional overflush and, as a result, hydraulic fracture closure at the wellbore. The loss of contact between the propped fracture and the perforated section of the well can neutralize the effect of hydraulic fracturing. This can happen in the first days of production after the operation or in a long-term perspective.
On the other hand, overflush during hydraulic fracturing is common practice for unconventional formations. It allows to use various well completion technologies with the cemented liners and significantly reduces time required to complete multistage fracturing treatment.
The objective of this paper is to show the approach and experience of the company "Salym petroleum development" (SPD). Positive result was obtained with proppant slurry overflush operation during treatment of conventional reservoirs.
Integrated petrophysical models have been broadly applied in geological and petro-elastic modeling to forecast hydrocarbon accumulations and to estimate resource potential. Methodological basis of building those models have been well developed for conventional terrigenous and carbonate reservoirs; as regards the so-called "shale-type" hydrocarbon-bearing rocks, however, there are objective difficulties determined by a range of various factors that may include multi-component composition of rocks, core recovery problems, as well as process-related peculiarities of laboratory methods. This paper offers a program of special laboratory core analysis of the samples from the Bazhenov formation and an algorithm for the processing of the results with the view to build an integrated petrophysical model of an unconventional "shale-type" oil pay.
With the view to obtain reliable information in difficult geological conditions, the oil and gas industry is increasingly mastering Big Data to optimize technological processes and prevent accidents. Contemporary Big Data technologies, predictive analysis and machine-learning methods are changing the general image of many industries, and the oil and gas industry is no exception. New players are quickly emerging throughout the industry, and digitalization will affect the entire value chain in the oil and gas industry. Among the most promising segments for the transition to digital technologies are asset management and infrastructure facilities, field development, geophysical services, pipelines and processing.
The applied production logging system using markers allows for evaluating horizontal well (HW) production after multi-stage hydraulic fracturing (MFrac). In addition, the performance of each oil and water stage can also be evaluated. Based on this information control, users can leverage the technology to optimize their operations.
The technology is based on the use of marker-reporters with quantum dots placed in the polymer proppant coating or in the lower completion. Unlike conventional methods of horizontal well logging, this technology does not require any special means of equipment delivery and eliminates the risk of downhole equipment getting stuck or ambiguous data interpretation.
From 2017-2019, production logging technology using markers was applied in more than 30 horizontal wells in the fields of LUKOIL-Western Siberia LLC.
We develop a novel ensemble model-maturation method that is based on the Randomized Maximum Likelihood (RML) technique and adjoint-based computation of objective function gradients. The new approach is especially relevant for rich data sets with time-lapse information content. The inversion method that solves the model-maturation problem takes advantage of the adjoint-based computation of objective function gradients for a very large number of model parameters at the cost of a forward and a backward (adjoint) simulation. The inversion algorithm calibrates model parameters to arbitrary types of production data including time-lapse reservoir-pressure traces by use of a weighted and regularized objective function. We have also developed a new and effective multigrid preconditioning protocol for accelerated iterative linear solutions of the adjoint-simulation step for models with multiple levels of local grid refinement. The protocol is based on a geometric multigrid (GMG) preconditioning technique. Within the model-maturation workflow, a machine-learning technique is applied to establish links between the mesh-based inversion results (e.g., permeability-multiplier fields) and geologic modeling parameters inside a static model (e.g., object dimensions, etc.). Our workflow integrates the learnings from inversion back into the static model, and thereby, ensures the geologic consistency of the static model while improving the quality of ensuing dynamic model in terms of honoring production and time-lapse data, and reducing forecast uncertainty. This use of machine learning to post-process the model-maturation outcome effectively converts the conventional continuous-parameter history-matching result into a discrete tomographic inversion result constrained to geological rules encoded in training images.
We demonstrate the practical utilization of the adjoint-based model-maturation method on a large time-lapse reservoir-pressure data set using an ensemble of full-field models from a reservoir case study. The model-maturation technique effectively identifies the permeability modification zones that are consistent with alternative geological interpretations and proposes updates to the static model. Upon these updates, the model not only agrees better with the time-lapse reservoir-pressure data but also better honors the tubing-head pressure as well as production logging data. We also provide computational performance indicators that demonstrate the accelerated convergence characteristics of the new iterative linear solver for adjoint equations.
Temizel, Cenk (Aera Energy) | Canbaz, Celal Hakan (Ege University) | Palabiyik, Yildiray (Istanbul Technical University) | Putra, Dike (Rafflesia Energy) | Asena, Ahmet (Turkish Petroleum Corp.) | Ranjith, Rahul (Far Technologies) | Jongkittinarukorn, Kittiphong (Chulalongkorn University)
Smart field technologies offer outstanding capabilities that increase the efficiency of the oil and gas fields by means of saving time and energy as far as the technologies employed and workforce concerned given that the technology applied is economic for the field of concern. Despite significant acceptance of smart field concept in the industry, there is still ambiguity not only on the incremental benefits but also the criteria and conditions of applicability technical and economic-wise. This study outlines the past, present and the dynamics of the smart oilfield concept, the techniques and methods it bears and employs, technical challenges in the application while addressing the concerns of the oil and gas industry professionals on the use of such technologies in a comprehensive way.
History of smart/intelligent oilfield development, types of technologies used currently in it and those imbibed from other industries are comprehensively reviewed in this paper. In addition, this review takes into account the robustness, applicability and incremental benefits these technologie bring to different types of oilfields under current economic conditions. Real field applications are illustrated with applications in different parts of the world with challenges, advantages and drawbacks discussed and summarized that lead to conclusions on the criteria of application of smart field technologies in an individual field.
Intelligent or Smart field concept has proven itself as a promising area and found vast amount of application in oil and gas fields throughout the world. The key in smart oilfield applications is the suitability of an individual case for such technology in terms of technical and economic aspects. This study outlines the key criteria in the success of smart oilfield applications in a given field that will serve for the future decisions as a comprehensive and collective review of all the aspects of the employed techniques and their usability in specific cases.
Even though there are publications on certain examples of smart oilfield technologies, a comprehensive review that not only outlines all the key elements in one study but also deducts lessons from the real field applications that will shed light on the utilization of the methods in the future applications has been missing, this study will fill this gap.
Serdyuk, Alexander (Rosneft) | Valeev, Sergey (Rosneft) | Frolenkov, Andrey (Rosneft) | Lushnikov, Alexey (Rosneft) | Overin, Alexander (Rosneft) | Yudin, Alexey (Schlumberger) | Kuznetsov, Alexander (Schlumberger) | Gorlushko, Anna (Schlumberger)
The Achimov formation in Western Siberia has considerable potential for oil production, but development of these hard-to-recover reserves often is not profitable. This paper focuses on successful experience of the Achimov development in the Prirazlomnoye field in Western Siberia, where a new technology of hydraulic fracturing was applied, which allowed us not only to increase the oil inflows, but also to significantly reduce costs of hydraulic fracturing.
The main geological properties of the Achimov formation of the Prirazlomnoye field are high heterogeneity, high gross thickness (exceeding 100 m in some cases), and water-saturated layers in the bottom section. Under these conditions, the hydraulic fracturing design should provide effective inclusion of all sublayers; therefore, a significant amount of fracture materials is required. In addition, there should be a mechanism to prevent proppant settlement in the lower part of the fracture. Channel fracturing treatment made it possible to achieve significant progress in solving the problems of reservoir development in the Achimov. Due to the features of the technology, the required amount of proppant and fluid was minimized, thus reducing the cost of hydraulic fracturing. High concentrations of fiber material in the hydraulic fracturing fluid fixed the proppant in the upper part of the fracture, significantly reducing the water-cut of well products.
The paper describes the details of the development of the Achimov on the Prirazlomnoye field using hydraulic fracturing. Statistical results show the optimal parameters of the hydraulic fracture. A comparative analysis of hydraulic fracturing using the standard and channel technologies was made. The well completion and production data from several pads were used, and a comparison was made of 47 wells that had channel technology applied with 39 offset wells fractured using standard technology. The average fracturing job size was more than 300 tons of proppant. The comparison reveals the advantage of a new method of fracturing on accumulated oil production (more than 10%); the increased production was mainly due to reduction of the water cut. At the same time, channel fracturing costs are lower by 12% compared to standard fracturing. Such a significant reduction in costs for large-tonnage jobs was achieved by decreasing of material volume for fracturing. The required proppant amount is decreased by 45% due to the specificity of the channel technology. In addition, due to the aggressive proppant concentration, increasing the volume of the required fracturing fluid is avoided, so costs for its delivery and heating are minimized. The application of the new fracturing technology significantly increased the profitability of the Achimov development.
The Achimov formation has been well explored geologically, but there have been few projects that demonstrably increased the profitability of development of these hard-to-recover reserves. This paper presents in detail an effective method for increasing the economic component in the development of hard-to-recover deposits. The potential of the Achimov formation in Western Siberia is significant, and the experience of channel fracturing at the Prirazlomnoye field can be applied to many other oil fields due to the reliability and adaptability of this fracturing technology.
The formulations and general approaches to the back analysis problems in verification of geomechanical models and in estimation of the parameters that govern the state and properties of mine-technical objects of any scale are considered. For the illustrative purposes, the authors propose the methods: canister test data interpretation which allows quantitative evaluation of gas-kinetic characteristic od coal (gas content, coefficients of diffusion and mass exchange) by the value of pressure in the sealed vessel containing slurry coal; determination of rheological characteristics of petroliferous strata with high content of organic matter by the thermobaric test results; prediction of weak seismicity level in the Baikal rift zone, induced by variation of water-level in the Lake Baikal; diagnosis of state of antiseepage screen at liquid effluent pond dam by the piezometric measurements in terms of thermohydrodynamic model of thawed and frozen rock mass.
Geomechanical evaluation of hard mineral mining technologies, estimation of stability of structures in underground and surface mines, geodynamic zoning of areas, analysis of hydrocarbon exposure and recovery scenarios—this is a far from complete list of problems solution of which needs data on deformation-strength characteristics of rocks and reservoir properties, as well as on external natural and induced fields. The implementation approaches are:
traditional method (Jaeger et al., 2007) when properties of rocks (parameters of state equations) are determined at a laboratory scale, while boundary conditions are set based on direct (
back analysis (Sakurai, 2017) when mathematical modeling includes integrally laboratory or in situ data by minimizing objective function.
The second approach is more broad-based as it allows using data of different physical nature (electromagnetic, temperature, hydrodynamic) by means of introduction of relevant objective functions:
where arguments are free parameters of a selected mathematical model, and a minimum point g (
The availability of ~ 7 years of actual performance data for the ongoing field-scale polymer flood in South of the Sultanate of Oman provides ample opportunities to reveal the reservoir dynamics and its interplay with induced EOR mechanism. The paper focusses on analysis of the polymer pattern behaviour, underlying reasons for such response and key indicators to characterize pattern performance. Upsets in surface polymer injection facility leading to the phenomenon of WAP (Water-Alternating-Polymer) and it's impact on recovery is also assessed in context of actual field examples. The paper then illustrates how this information could be exploited to counter challenges faced in the field, enhance polymer pattern performance, optimize it's further expansion and de-risk any other future EOR development.
A nested modelling approach has been employed, wherein models at different scales are generated, tailored to meet the objectives. High resolution 3D conceptual models are built in Shell proprietary tool PolyMoReS to calibrate the model response against the actual polymer pattern behaviour in the field, study the impact of mixing between polymer and water slugs in WAP type of recovery, and affirm the correct polymer rheology. Three segment models covering the field are created and history matched with the use of Stochastic Uncertainty Management. Attempts have been made to obtain history match (HM) on segment, pattern and well levels, with greater emphasis on polymer patterns capturing polymer oil response, water-cut reversals and polymer breakthroughs. Models are then complemented by Pressure Fall-Offs, tracer tests and PLTs to capture uncertainties in fracture growth and areal and vertical conformance. The HM model is then used to predict polymer performance.
Significant insights into waterflood and polymer flood performance are gained, which help improve the pattern performances. Assessment of WAP with both conceptual Physics and field segment models demonstrate considerable deferment of oil. Capturing injector – producer connectivity has proven the most pivotal element in explaining polymer oil response and breakthrough.
Models indicate that lower than expected incremental recovery and sharper decline of oil response in some patterns are related to the lower polymer mass injected, which in-turn could be attributed to many operational factors (e.g., polymer injection uptime, injection rate, low injection viscosity, WAP), and the presence of natural fractures or uncontrolled growth of induced fractures. The study also reveals optimization opportunity to reduce the volumes of back produced water.
The paper presents a comprehensive multi-scale reservoir modelling study for a field with significant historical data of large scale polymer flood. Impact of WAP injection, reflecting the reality of interruptions in polymer flood due to operational upsets, on medium to long term polymer flood value is presented. Analysis of polymer patterns in the field demonstrates how different key indicators e.g., PUF (Polymer Utilization Factor) can characterize pattern performance throughout its life-cycle and answers questions, e.g., why some patterns behaved well, while others not.
In studying and development of unconventional reservoirs, it is important to know vertical component of resistivity. This information can be obtained by HRLA or Rt-Scanner type devices, but due to low oil prices, using of them in Russia is becoming economically inexpedient. This leads to the necessity to develop a quantitative interpretation of the data of traditional Russian electrologging methods, which can provide information of the structure and properties of deposits with minimal cost. In vertical wells, in high-resistivity deposits similar to the Bazhenov formation, gradient sondes are sensitive to anisotropy, which was shown by the results of modeling and interpretation of signals on a one-dimensional cylindrical-layered model (
In this paper, I propose a technique for processing BKZ data measured in complicated geological medium with small thicknesses of interlayers. To increase the accuracy of determining the parameters of an anisotropic medium, a two-dimensional geoelectric model and finite-element algorithms for solving direct problems are used. The geological object of study is a major source of unconventional oil in Russia – the Bazhenov formation, but the proposed technique is applicable to other objects. Based on the results of data processing for 18 wells from the Fedorovskoe and Russkinskoye fields, the features of resistivity anisotropy coefficient distribution by depth at intervals of the Bazhenov formation have been revealed.
This paper presents the innovative practices and methods to reduce the environmental impact of an EOR project in the Daqing oilfield. Field results were presented to validate those effective management practices in terms of reducing environmental impact.
Environmental protection is becoming more and more important in terms of EOR processes. In this study, an environment friendly surfactant and polymer system were developed and applied in current EOR Project. A new injection system for this EOR system was also designed to minimize carbon footprint by the deployment of much smaller in size and weight equipment without compromising performance and safety. In addition, on-site collection and recycling technique is applied to reuse chemicals instantly onsite to minimize environmental storage problems and environmental exposure of these materials.
Field application of this novel surfactant and polymer system for EOR satisfies government's environmental health and safety requirements. The new designed injection system uses less than 60% electric power than previous traditional injection systems on average. The system is skid-mounted and very flexible, further reducing additional manpower without compromise performance and safety. Oil spills were substantially reduced to the lowest levels by 48%. Chemical spills were reduced almost by 80% at in-house locations. Chemical recycling also reduced total chemical costs by 10%, along with the reduction in associated HSE impact.
The practices in this paper achieved both the production goals and reduction of environmental impact when deploying this new surfactant and polymer system for EOR. Reduction of environmental impact can be achieved without compromising performance and safety in EOR operations.