This month we heard from the Hungary Section. Gábor Takács and Bela Pertik established the Section with the support and participation of MOL's oil engineers. The opportunity to collaborate with others and share best practices with colleagues. The Section also provides an environment to access information about the latest technical challenges in the region and learn from experts in specific technical disciplines. The Hungarian Section Leaders communicate with members directly, we know every member of the section personally.
Reservoir conformance control (RCC) might be fundamental designing profitable production technology in oilfields. Appropriate application of RCC methods can significantly result in improved IOR/EOR through reduced water production and profile correction. In the past decades, numerous techniques were extensively applied with these goals; however, the operators did not appreciate the silicates until mid-1970s despite the fact that emblematic professionals proposed the silicate gels as efficient alternatives to organic gel technologies. Recently, the attitude towards the extensive use of silicates in oilfields has changed. The silicate-based water shutoff treatments and profile control methods have been already used more than hundred times in Hungary, Serbia, Norway, USA, Oman, and other countries. In the past several years, the fundamental and applied research focused on elimination of inherent negative properties of pure silicate gels, and development of efficient and flexible technologies using polymers and nanosilica in the treating solutions. As a result, the diverse silicate RCC methods arouse high interest in oilfield applications. Today, the
The presentation summarizes the results of both the fundamentals and a pilot tests accomplished in the Algyő field, and critically analyzes the lessons to learn. Base on the publications disseminated until now it can be concluded that these field jobs demonstrate outstanding responds both in water cut and increased oil rate. It was also proved that the nanoparticle-induced (nucleated) formation of silicate gels could potentially be used in all types of porous and fractured reservoirs. In addition, the in-situ formed gels have outstanding thermal stability up to 150°C, the chemicals are mass-produced and available at low price, the job needs simple surface facilities, and customary human force to operate the RCC method. Consequently, the
MOL Group is an integrated, international oil and gas company headquartered in Budapest, Hungary, with lead position in its core markets within Central and Eastern Europe. Its northern region downstream business consists of two complex refineries and and three steam crackers at two locations. To be able to exploit synergies thus to maximize potential profitability of assets via transfer connections, current downstream planning activities are performed on group level in a multi-site linear planning model resulting in simultaneous optimization possibility of petrochemical and refinery sites. In such a planning model system, next to internal asset constraints, specific utility costs and market purchase or sales conditions drive the optimization result. It does not only support optimal feedstock selection for both refinery (different crude oils provide different yield structure) and petrochemicals (LPG against naphtha feedstock) together with their most profitable asset configuration, but it also enables proper setting of refinery product portfolio against polimer production. In current MOL Group solution, an additional aspect has been implemented for improving the refinery-petrochemical connection: next to its volumetric effect, specific quality of produced petrochemical naphtha feedstock is also considered within the optimization as this information is channeled into the olefin plants in order to better estimate monomer yields of the steam cracker. It provided another milestone of this simultaneous optimization challenge thus improved on its delivered results. The paper focuses on our current best practices by demonstrating how above planning system features support MOL Group Downstream to derive right business decisions. It furthermore explains how our development roadmap puts emphasis on further refinement of the refinery-petrochemicals connection, utilizing state-of-the-art technologies like upgrading our linear optimization models with nonlinear correlations.
The program for the final disposal of low and intermediate level radioactive waste was established by Paks Nuclear Power Plant, Hungary. Preparation of final disposal has been done as part of a national program since 1993. The Central Nuclear Financial Fund and the Public Limited Company for Radioactive Waste Management (Puram) have been established to coordinate organizations and activities for all tasks in connection with nuclear waste treatment. The project was started with a geological screening in order to find the most suitable geological formation for radioactive waste repository. The selected potential host rock is a granite complex in the Mórágy Granite Formation in the south-western part of Hungary, close to the village of Bátaapáti.
In the underground facility different measuring systems have been used (extensometers, inclinometers, convergence measurements), requiring a transformation into radial and tangential displacements. Until now not much emphasis was laid on the 3D geodetical displacement monitoring measurements or on the use of advanced methods such as the evaluation of displacement vector orientations.
The final survey results are ensured by the Mecsekerc Ltd. Department of Geodesy as a daily actualized database with Unified National Projection system (EOV) coordinates. Upon request the surveyors provide data in local coordinates (they provide relative and absolute coordinates simultaneously), allowing a meaningful analysis. The aim of this paper is to shortly introduce the surveying process and interpretation of the 3D optical displacement measurement methodology. Our research is related to geodetic measurements which were carried out in the repository chambers and some exploratory tunnels. The mentioned exploratory tunnels crossed through fault zones. We have studied the effect of the fault zones on the measured 3D displacements, using the common evaluation and displacement prediction methodologies, and we show the results obtained during the control of the „normality” of the displacements from the underground spaces which were excavated full face and at larger sections by top heading and bench method. The results of the presented case studies show that the 3D optical displacement monitoring enables the prediction of the geotechnical conditions ahead of the face and the influence of fault zones located outside of the excavated space.
Buocz, Ildikó (Budapest University of Technology and Economics) | Rozgonyi-Boissinot, Nikoletta (Budapest University of Technology and Economics) | Török, Ákos (Budapest University of Technology and Economics)
Shear strength along rock discontinuities by means of direct shear strength tests were performed on granitic and clayey rocks. Both rock types represent potential host rocks of radioactive waste. The paper focuses on the effect of one parameter in particular influencing the shear strength: the angle enclosed by the plane of the sample surface and the shear plane, in the direction of shear. 3D surface roughness measurements were carried out on 18 Opalinus Claystone sample (Switzerland) and 6 on granitic rock sample (Hungary) surfaces. An interval of angle was analyzed in the direction of shear and against the direction of shear. Direct shear strength tests were carried out under constant normal loading (CNL) conditions, the influence of the angle on the shear strength values were determined. Additionally, a percentage value was calculated for how much the range of both peak and residual shear strength values change, with taking into consideration the effect of upslope and downslope shear.
Designing and constructing in rock masses require a detailed and sound knowledge of the mechanical properties of the rock materials involved. Failure of rocks and determination of appropriate failure envelope has been studied for a long time [1, 2], however one of the most important parameters controlling the strength of rock masses is the shear strength of the discontinuities . The discontinuities are usually a weak point of the rock mass; in particular, the features of their surfaces, such as roughness, joint strength, brittleness, humidity, mineralogy, (etc.) determine its strength. Mechanical, test related factors i.e.: loading conditions, type of testing machines, (etc.) influence the shear strength as well. The mechanical parameters defining the shear strength, i.e. friction angle and apparent cohesion, are investigated by means of laboratory direct shear strength tests. The basic principles of such analyses and test methods have been already published [4, 5, 6].
In this paper one parameter influencing shear strength was investigated in particular: the angle between the sample surface and the shear surface in the direction of the shear, resulting in “upslope” or “downslope” shearing. The paper compares the results of upslope and downslope shearing for granites and claystones. Both rock types represent target formations for hosting radioactive waste in Hungary [7, 8] and in Switzerland [9, 10, 11], respectively.
Pál Farkas, Márton (GFZ - German Research Centre for Geosciences, Golder Associates Hungary) | Dankó, Gyula (Golder Associates Hungary) | Yoon, Jeong Seok (GFZ - German Research Centre for Geosciences) | Zang, Arno (GFZ - German Research Centre for Geosciences) | Zimmermann, Günter (GFZ - German Research Centre for Geosciences) | Stephansson, Ove (GFZ - German Research Centre for Geosciences)
Multistage mini hydraulic fracturing tests were performed in a borehole located in central Hungary in order to determine in-situ stress. At depth of about 500 to 560 meters, observed pressure versus time curve in metamorphic rock (mica schist) show a typical results. After each pressurization cycle, the fracture breakdown pressure in the first fracturing cycle is lower than the reopening pressures in the subsequent reopening and step-rate phases. It is assumed that the composition of the drilling mud and observed foliation of the mica schist have a significant influence on the pressure values. In order to investigate this problem, numerical modeling was performed using the discrete element code (ITASCA Particle Flow Code, PFC), which has been proven as an effective tool to investigate rock engineering problems associated with hydraulic fracturing. The code presented in this study enables simulating hydro-mechanically coupled fluid flow in crystalline rock with low porosity and pre-existing fractures (represented by the smooth joint contact model in PFC) in two dimensions. In this study, the sensitivity of the effect of foliation angle and fluid viscosity on the peak pressure is tested. The anomalous characteristics of the pressure behavior are interpreted in that way that the drilling mud penetrates the sub-horizontal foliation plane, it clogs the plane of weakness and makes the opened fracture tight. Eventually, the process prevents leak-off from the opened fracture that might explain the increased fracture reopening pressure in subsequent cycles.
Hydraulic-driven fractures play a key role in energy technologies. In particular, unconventional oil, shale gas and geothermal reservoirs are often characterized by in-situ rock with intrinsic low permeability. Prior to any energy production, minifrac, micro-hydraulic fracturing or extended leak-off test are an efficient way to gain knowledge about in-situ stress field of rock near the wellbore. This direct method means pressurizing an isolated interval of an open borehole section until the rock fractures hydraulically. An obvious signature of fracturing and hence fluid leakage into formation is the non-linear behaviour in the pressure versus time relationship, that is, breakdown in the pressure curve.
This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 174174, “Integrated Approach To Managing Formation Damage in Waterflooding,” by Sergey Aristov, Paul van den Hoek, and Eddie Pun, Shell, prepared for the 2015 SPE European Formation Damage Conference, Budapest, Hungary, 3–5 June. The paper has not been peer reviewed. This article is reserved for SPE members and JPT subscribers.
This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 174174, “Integrated Approach To Managing Formation Damage in Waterflooding,” by Sergey Aristov, Paul van den Hoek, and Eddie Pun, Shell, prepared for the 2015 SPE European Formation Damage Conference, Budapest, Hungary, 3–5 June. The paper has not been peer reviewed.Understanding of formation damage is a key theme in a waterflood project. An integrated multidisciplinary approach is required to determine an optimal design and strategy. An operator has developed a suite of tools to tackle these issues and help in adequate design and optimization of waterfloods.
Many waterfloods in the operating phase do not perform as expected. Often this is because of well-injectivity issues where the required water quality for the injected water is either not properly defined (i.e., by the subsurface disciplines) or not properly managed (i.e., at the surface facilities). A rapid decline in well injectivity can result when injecting under matrix conditions, and a loss in reservoir containment caused by out-of-zone injection (OOZI) or a short-circuiting injector and producer can occur when injecting under fractured conditions, all negatively affecting reservoir sweep.
Subsurface and Subsurface-Modeling Work Flows
To determine an optimal waterflooding concept, it is important for the integrated work flow that the outcome of the sub-surface assessment be a range of technically feasible scenarios. These scenarios should incorporate the ranges in subsurface uncertainties combined with sub-surface concept options. The objective for the subsurface work flow is to define for each of these scenarios the production profile for the field, injection volume, quality of injected water, number of injection wells, subsurface targets, risk, and mitigations.
The subsurface work flow is illustrated in Fig. 1 of the compete paper. The following main steps are identified: