Ivanova, Anastasia (Curtin University, Skolkovo Institute of Science and Technology) | Orlov, Denis (Skolkovo Institute of Science and Technology) | Mitiurev, Nikolai (Emanuel Institute of Biochemical Physics, Russian Academy of Sciences) | Cheremisin, Alexey (Skolkovo Institute of Science and Technology) | Khayrullin, Marsel (VNIIneft) | Zhirov, Alexey (VNIIneft) | Afanasiev, Igor (Zarubezhneft) | Sansiev, Georgy (Zarubezhneft)
More than a half of world's hydrocarbon reserves is presented in carbonate reservoirs. Conventional waterflooding leads to inefficient oil recovery from these reservoirs, because majority of them have mixed or oil-wet wetting properties. It is well documented in literature, that the main reason of oil wetness of carbonate rocks is adsorbed components from crude oil. Although progress has been made in determination of oil components, which have a tendency to react with carbonates, carbonate reservoirs development still remains challenging. Hence, in this study we investigated the distribution of adsorbed oil components on rock surfaces in order to define their influence on fluids flow through porous carbonate samples. This work presents the results for several carbonate core samples taken from the oil zone of an oil reservoir, which mostly consist of calcite with the small impurities of magnesite and quartz. The work provides the standard study of pore structure of samples to assess the solvents influence on pore network of samples using μCT; the method of evaluation of the amount of organic matter adsorbed on calcite using Rock - Eval pyrolysis; the visualization of such matter distribution through samples; and also the results of kinetics experiments in order to evaluate the bond disruption energy between organic matter and surface. Studies have shown that combination of pyrolysis and μCT provides comprehensive and improved data about organic matter.
Mudstone (shale) reservoir evaluation and efficient development poses a significant challenge due to the heterogeneous nature of these complex formations. Organic-rich shales are characterized by intricate mineralogy, ultra-low nanoporosity, and nano-darcy permeability making these tight source/reservoir rocks challenging in obtaining economically viable hydrocarbons. Consequently, characterizing and quantifying minerology and intra-/interparticle (non)organic-hosted porosity at the pore-scale, and up-scaling it to the core-scale remains a significant focus of evaluating reservoir quality in shale plays.
Current advances in correlative multi-scale and multi-modal 2D/3D imaging of nanoporous geomaterials, such as shales, provide a tremendous opportunity to characterize and represent these rocks over multiple length scales – from core-to pore-scale. Subsequently, these image datasets can be then used for advanced image analysis and digital rock modeling to reconstruct 2D/3D models used to analyze their petrophysical properties.
In this study, the Mancos Shale from the Uinta Basin – one of the most promising shale plays in the United States (
Low temperature (60 and 100 °C) and long-term (6 months to 5 years) heating of pre-evacuated and sterilized shales and coals containing kerogen Types I (Mahogany Shale), II (Mowry Shale and New Albany Shale), and III (Springfield Coal and Wilcox Lignite) with low initial maturities (vitrinite reflectance Ro 0.39 to 0.62%) demonstrates that catalytically generated hydrocarbons may explain the occurrence of some non-biogenic natural gas plays where insufficient thermal maturity contradicts the conventional thermal cracking paradigm. Extrapolation of the observed rate of catalytic methanogenesis in the laboratory suggests that significant amounts of sedimentary organic carbon can be converted to relatively dry natural gas over tens of thousands of years in sedimentary basins at temperatures as low as 60 °C.
Our laboratory experiments utilized source rock chips sealed in gold and Pyrex® glass tubes in the presence of hydrogen-isotopically contrasting waters. Parallel heating experiments applied hydrostatic pressures from 0.1 to 300 MPa. Control experiments constrained the influence of pre-existing and residual methane in closed pores of rock chips that was unrelated to newly generated methane.
This study’s experimental methane yields at 60 and 100 °C are 5 to 11 orders of magnitude higher than the theoretically predicted yields from kinetic models of thermogenic methanogenesis, which strongly suggests a contribution of catalytic methanogenesis. Higher temperature, longer heating time, and lower hydrostatic pressure enhanced catalytic methanogenesis. No clear relationships were observed between kerogen type or total organic carbon content and methane yields via catalysis. Catalytic methanogenesis was strongest in Mowry Shale where methane yields at 60 °C amounted to ~2.5 μmol per gram of organic carbon after one year of hydrous heating at ambient pressure.
Future studies need to evaluate the possibility that clumped isotope characteristics of catalytically generated methane can diagnose the low-temperature regime of catalytic methanogenesis. Furthermore, testing of freshly cored anoxic rocks is needed to determine whether the use of archived, oxygen-exposed rocks in geochemical maturation/catalysis studies introduces artifacts in hydrocarbon yields.
Twenty-one national geological surveys contributed to the European wide project ‘EU Unconventional Oil and Gas Assessment’ (EUOGA). The goal of EUOGA was to assess all potentially prospective shale formations from the main onshore basins in Europe and included contributions of twenty-one European geological surveys. Each participating geological survey characterized their domestic shale plays using thirty systematic parameters such as areal distribution, structural setting, average net to gross ratio of the shale reservoir, average Total Organic Carboncontent (TOC) and average mineralogical composition. The assessment covers 82 geological formations from 38 basins. Subsequently a stochastic volumetric probability assessment was performed on 49 of these formations which met the prerequisites for assessment. Importantly, this study for the first time used a unified methodology for assessing resources across European borders. Paleozoic plays in Poland, the United Kingdom, Denmark and Ukraine hold the largest potential gas resources. Most shale oil potential is observed in Bulgaria, the United Kingdom and Ukraine. The total resource potential for the geological formations that were evaluated in the project is 89.2 trillion cubic meter of gas initially in place (GIIP P50) and 31.4 billion bbl of oil initially in place (OIIP P50). The outcome of this project represents the most complete and accurate determination of shale hydrocarbon resources in Europe to date.
Europe may hold significant volumes of unconventional hydrocarbons as has been showed by both national and international agencies (e.g., EIA 2011, 2013, van Bergen 2013, Andrews 2013, 2014 , BGR 2012, Ladage 2016, PGI-NRI 2012). Interpretation and comparability of these studies is problematic, primarily due to difference in assessment methodology and both the quality and quantity of geological data that was available for the different plays. As a consequence the total European shale resource potential remains uncertain making long term planning, both political and economic, difficult. To overcome this problem a uniform assessment of European shale resources was required tailored to the specific challenges of the European situation.
ABSTRACT: The aim of this paper is to present workflow of implementing 1-D geomechanical analysis for optimization hydraulic fracturing design. Well stress modelling is very important in case of optimal stimulation of unconventional shale formations. It can be achieved by generating complex fracture system around the horizontal wellbore. Properly designed hydraulic fracturing is currently the best way to improve contact between well and unconventional reservoir. Data gathered during hydraulic fracturing treatments resulted in calibration existing geological models and optimization of future well completions. Geomechanical modelling and results obtained from Lublin Basin Silurian shale formation hydraulic stimulation are good example of cooperation between geology and engineering teams. Similar analysis can be transferred to other unconventional basins, regarding to acquire enough data. The examples showed in this paper illustrate iterative workflow of the ORLEN Upstream Ltd. in improving hydraulic fracturing design. Furthermore, it also demonstrates production potential of shale formations of the Lublin Basin and determines way for exploration unconventional rocks in Poland.
The unconventional hydrocarbon resources may affect more and more on global energy balance. A number of international oil and gas companies, including Polish ones, already done several projects to acquire commercial hydrocarbon production from shale formations in Poland. ORLEN Upstream Ltd. has encountered experience on exploring unconventional Paleozoic shale formations of the Lublin Basin. Described in the article operations had been conducted in the years 2011-2015 and leaded by a highly qualified team, based in Warsaw, representing upstream segment in the PKN ORLEN S.A., the biggest company in central and eastern Europe, originally downstream oriented and developing its oil & gas activity since 2006.
Exploration and production of unconventional plays requires integration and cooperation across geological and engineering teams. As mentioned previously by Wikel, 2011, geomechanics is recently becoming more appreciated bridge between geological sciences and engineering practice. It is also one of the most impacting parameters of shale reservoirs. Geomechanical parameters determines how borehole instability features appears, how hydraulic fractures grows and how much proppant can be pumped into formation.
Yang, Zhao (PetroChina) | Fenjin, Sun (PetroChina) | Bo, Wang (PetroChina) | Xianyue, Xiong (PetroChina) | Wuzhong, Li (PetroChina) | Lianzhu, Cong (PetroChina) | Jiaosheng, Yang (PetroChina) | Meizhu, Wang (PetroChina)
Compared with the conventional oil and gas reservoirs, hydrogeological gas controlling process linking CBM accumulation, enrichment and high yield is one of the important scientific problems for the development of a CBM field. Previous research results are mainly focused on the impact of hydrodynamics on CBM dissipation, preservation and enrichment, whereas relatively less work has been done on the quantitative evaluation of the hydrochemical field of CBM and establishing evaluation indicators of CBM enrichment. Therefore, taking BQ Well area of Hancheng block in east Ordos Basin as an example, this paper tried to initiate a systematic analysis of the controlling function of hydrogeological conditions on the enrichment and high yield of CBM in the study area. Hydrological evaluation indicators for hydrocarbon enrichment zones are established and two favorable hydrocarbon enrichment zones are optimized. It is of great significance for the established analytical method of hydrogeological rule on the studies of CBM enrichment characteristics and development in Hancheng CBM block, and subsequent exploration & development in the neighboring blocks.
Firstly, the relevant principle of hydrodynamics is applied to identify substantive parameters, such as measured in-situ reservoir pressure and CBM reservoir water level in the production wells to calculate the reduced water level and analyze groundwater level distribution characteristics; secondly, combined with the analysis of groundwater water types, the sources of the produced water from coal beds are identified, and the sealing property of the reservoir is demonstrated; on this basis, the study area is divided into the weak runoff zone and the stagnation zone. It is considered that the runoff intensity is relatively weak and the sealing capability is good in the study area, with no external water intrusion; finally, it is considered that, through integrated studies on the hydrochemical field, the desulfuration coefficient and sodium chloride coefficient can reflect the diversity of CBM reservoir conditions in a more elaborated way. Hydrological indicators based on hydrochemical characteristics are established, and two favorable enrichment zones are predicted.
This work proved that hydrogeological features of CBM reservoirs are able to characterize their accumulation conditions elaborately. In particular, the establishment of hydrological indicators can classify favorable enrichment zones and hereafter guide following CBM exploration & development. This methodology has been satisfactorily applied in BQ well area of Hancheng block where the data of gas bearing capacity is limited. High single well production rates have been obtained in the two predicted favorable enrichment zones. The hydrological indicators established in this paper are expected to be popularized and applied in other well areas of Hancheng block, which may accelerate the overall exploration & development progress in this block.
Handwerger, D.A. (Schlumberger) | Castañeda-Aguilar, R. (Schlumberger) | Dahl, G.V. (Schlumberger) | Borgos, H. (Schlumberger) | Zacharski, J. (Orlen Upstream) | Krawiec, D. (Orlen Upstream) | Buniak, A. (Orlen Upstream) | Prugar, W. (Orlen Upstream) | Suarez-Rivera, R.
For many unconventional reservoirs, interpretation of subsurface geology alone can be inadequate for determining reservoir potential. As a result, seismic data have not been as fully utilized as they could be. This paper presents a study that leverages multivariate classification methods to integrate core, log and seismic data for the propagation of material properties across two intersecting 2D seismic lines in the Lublin Basin, Poland.
In this study, classification of wireline logs is used to isolate zones of expected similar or different material properties. These classes are then integrated with core data in order to determine which classes are most favorable from both a reservoir quality and completion quality perspective (ability to stimulate), based on the large assortment of core measurements. Following characterization of the classification model at log scale, the collection of pre-stack inverted seismic attributes from each 2D line was trained at the near-well traces to recognize the classes provided by an upscaled version of the log-derived classification model. Once the training rules were determined, they were applied to the full 2D data in order to propagate the classes away from the wellbore, and by extension the estimation of all the material properties integrated with the classes from the core measurements.
Within the study region, one training well near the intersection of two 2D lines was used. This training well was on the down-thrown block of a large fault identified on one of the lines. Application of the training rules to the seismic attributes on the up thrown block across the fault shows that the up thrown block likely contains a new set of classes (and hence new and uncharacterized material properties) largely different from those available to train the model from the single available well and core. This integrated approach also showed that there is significant vertical and lateral heterogeneity in this portion of the Lublin Basin and that multivariate classification can be an effective means to integrate, scale and propagate material properties through a basin, even with limited available seismic data.
Krzywiec, Piotr (Institute of Geological Sciences, Polish Academy of Sciences) | Volterrani, Stefano (ION Geophysical) | Slonka, Lukasz (Institute of Geological Sciences, Polish Academy of Sciences) | Lis, Pawel (GeoFuture Consulting) | Buffenmyer, Vinton (ION Geophysical) | Malinowski, Michal (Institute of Geophysics, Polish Academy of Sciences) | Lewandowski, Marek (Institute of Geological Sciences, Polish Academy of Sciences)
The western edge of the East European Craton in Poland has recently been the focus of intense exploration efforts for unconventional hydrocarbons, led by Polish and foreign companies. Results of early exploration wells clearly demonstrate that there are still many unknowns regarding various aspects of the unconventional petroleum system, both regional (structure and depositional architecture of the Lower Paleozoic succession) and more local (variations of shale thickness, TOC, mechanical properties etc.). In order to shed light on some of these problems high-effort regional reflection seismic survey PolandSPAN has been acquired that covered entire Lower Paleozoic basin developed above the SW edge of the East European Craton. Following regional interpretation a feasibility study devoted to seismic reservoir characterization has been completed that allowed to assess applicability of seismic reflection data for reservoir-oriented studies of the Lower Paleozoic shales in Poland.
The Lower Paleozoic basin in Poland is located above the southwest edge of the East European Craton, northwest from the Teisseyre – Tornquist Zone which is separating the cratonic plate from the West European Platform (Ziegler, 1992; Doornenbal & Stevenson, 2010). Later Late Paleozoic tectonic movements resulted in compartmentalization of the Lower Paleozoic basin into three sub-basins: Baltic Basin, Podlasie Basin and Lublin Basin (Fig. 1). During the Precambrian/Cambrian, the cratonic edge underwent extension and rifting of the Rodinia supercontinent, while Cambrian – Middle Ordovician subsidence was driven by a post-rift lithospheric thermal cooling (Poprawa et al., 1999; Poprawa, 2006a). In the Late Ordovician – Silurian, the cratonic edge was under the strong influence of the Caledonian thrust belt, and was incorporated into its flexural foredeep basin (Poprawa et al., 1999; Nawrocki & Poprawa, 2006). Deposition was dominated by fine-grained organic rich shales, generally derived from the eroded orogenic wedge and deposited in the distal foredeep basin (Poprawa et al., 1999; Poprawa, 2006b). The Silurian Caledonian foredeep basin encompassed vast areas stretching from the present-day Sweden across Estonia, Latvian, Lithuania, Russia (i.e. Kaliningrad District), Poland, Belarus, Ukraine and farther to the southeast (Poprawa et al., 1999; Skompski et al., 2008; Zdanaviciute and Lazauskiene, 2007). Presently available information regarding the Caledonian orogenic wedge is very limited and mostly indirect, based on e.g. provenance studies of the foredeep infill, as it was destroyed and deeply buried during the later tectonic phases (Poprawa, 2006b).
Seismic data acquisition and processing
In order to study Lower Paleozoic shales deposited above the cratonic edge, approximately 2200 kms of regional high-effort seismic reflection data has been acquired. The main acquisition parameters can be summarized as follows:
Silurian black shales in Central and Eastern Europe (CEE) attracted lots of companies interested in unconventional shale gas exploration.The present day collage of various Silurian basin fragments in CEE is the result of several orogenic and rifting/drifting episodes. The proper paleogeographic reconstruction of a single, very large Silurian foredeep basin in the context of basin-scale geology has a major impact on the ongoing unconventional shale gas exploration efforts in the broader region.
The distal segments of a large Silurian foreland basin associated with the Caledonian collisional orogene, along the perimeter of the East European Craton, can be reasonably followed along strike from NW to SE, from Poland all the way to the Ukrainian Black Sea coast. The foredeep basin sequence onlaps to the NE the various pre-Silurian and crystalline basement units. The Silurian basin of the CEE is interpreted here as a pro-foreland basin, with short-lived (less than 15 m.y.) and extremely rapid (locally more than 1,500 m per m.y.!), accelerating subsidence histories recording only a portion of the orogenic history of the Caledonian orogeny. Besides the typical subsidence curves and prominent onlap onto the craton, the flexural origin is also supported by the general lack of normal-faulting within the basin, contradicting interpretations suggesting deposition on the passive margin of the Rheic Ocean. The map-view distribution of the lithofacies within the basin, such as clastic turbidites in the southwestern perimeter of the basin, deepwater shales in the center and neritic carbonates on the northeastern foreland margin, is also consistent with the flexural basin interpretation. This new interpretation may have some predictive power as to the temporal and spatial distribution of sweet spots for unconventional exploration targeting Silurian black shales in the broader CEE region.
Jones, P. J. (Halliburton) | Karcher, J. (Halliburton) | Ruch, A. (Halliburton) | Beamer, A. (Halliburton) | Smit, P. (Halliburton) | Hines, S. (Halliburton) | Olson, M. R. (Marathon Oil Corporation) | Day, D. (Marathon Oil Corporation)
Sound wellbore construction and maintenance are essential to the successful development and production of hydrocarbons from unconventional resources. During the development of a Polish shale play near the Ukrainian border, the integrity of a well under construction became compromised due to a breach in an external casing packer on the production string. Successful completion of this well would require fracture-stimulation operations at pressures of up to 9,000 psi, which would be impossible unless the breach could be repaired. A cementing valve just above the breached packer had already reduced the inside diameter on the 4-1/2 inch production string to 3.827 inches. The difficulty of running a casing patch in this restricted environment and the further reductions in diameter eliminated this from being a preferred solution. In addition, the high pressures associated with fracturing operations warranted an innovative solution rather than a conventional approach. Recently commercialized resins displayed the ability to withstand stresses over 10,000 psi and compressive strains greater than 40% without failure. However, case histories on field deployment of these materials, their ability to be drilled, and performance after hydraulic fracturing were essentially non-existent. This paper presents a case history on the laboratory development of a customized resin solution, the rigless operation using coiled tubing to place the materials and repair the breached packer, and the drill-out after placement. Effectiveness of the remedial operation was determined by subsequent pressure testing. After restoring wellbore integrity, hydraulic fracturing operations were able to be completed, and successful production from this well began.