Tian, Hua (Research Inst Petr Expl & Dev, Petrochina) | Zou, Caineng (Research Inst Petr Expl & Dev, Petrochina) | Liu, Shaobo (Research Inst Petr Expl & Dev, Petrochina) | Zhang, Shuichang (Research Inst Petr Expl & Dev, Petrochina) | Lu, Xuesong (Research Inst Petr Expl & Dev, Petrochina) | Ma, Xingzhi (Research Inst Petr Expl & Dev, Petrochina) | Bi, Lina (Research Inst Petr Expl & Dev, Petrochina) | Yuan, Miao (Research Inst Petr Expl & Dev, Petrochina)
A series of petrohysical experiments have been conducted to obtain the gas physical properties (e.g., gas-water interfacial tension). The capillary pressures of pore throats were obtained through numerical calculation. Furthermore, residue water was used to calculate gas/water saturation in the reservoirs. The gas saturation variation under lower interfacial tension and the amount of gas lost during the uplift in burial history need an in-depth examination (Tian et al., 2017). In addition to the geological studies in the field, various laboratory methods were used to tackle the problems mentioned above, including Nlear nuclear magnetic resonance (NMR) and fluid inclusion analysis with optical and Laser Raman spectroscopy. During the charging history, hydrcarbon saturations at different temperature and pressure was calculated using the model established in this paper, which is mainly determined by the pore size distribution obtained by the NMR analysis. The charging pressure is measured by fluid inclusion study with optical and Laser Raman spectroscopy test. Furthermore, the leakage content of gas during the burial history was calculated using a diffusion model (Krooss& Leythaeuser., 1988; Krooss et al., 1992).
The Cambro-Ordovician succession of Saudi Arabia comprises dominantly siliciclastic sediments deposited in a passive margin intracratonic setting and includes the fluvial to marginal marine Saq Formation (Late Cambrian to early Middle Ordovician), the marine Qasim Formation (late Middle to Late Ordovician) and the glaciogenic Sarah Formation (Hirnantian, latest Ordovician). The Saq Formation is subdivided into the Risha Member (Late Cambrian) and the Sajir Member (Early to Middle Ordovician). Palynological age-control in the Risha Member is provided by a characteristic acritarch assemblage (CB1 Palynozone) which contains well-known Furongian (Late Cambrian) diagnostic taxa (e.g., Trunculumarium revinium, Timofeevia phosphoritica and Ninadiacrodium dumontii), as recorded in one subsurface locality in the Arabian Gulf. This typical assemblage occurs worldwide in Furongianaged strata and not only permits a confident age-attribution, but also indicates an open marine facies within the predominantly fluvial to marginal marine lower Saq Formation. In Oman, the same assemblage occurs in the Al-Bashair Member of the Andam Formation. In the lower part of the Sajir Member, one acritarch assemblage characterized by the presence of Acanthodicaodium angustum and Vulcanisphaera spp., was described from a subsurface section in Eastern Saudi Arabia, indicating an earliest Ordovician (Tremadocian) age. This assemblage forms the O6 Palynozone and suggests correlation with the Mabrouk Member of the Andam Formation in Oman.
Chen, Xiaoer (Institute of Sedimentary Geology, Chengdu University of Technology, Geophysical Technology Research Centre, BGP, CNPC) | Fan, Kun (Southwest Geophysical Research Institute, BGP, CNPC) | Ren, Chenghao (Southwest Geophysical Company, BGP, CNPC) | Li, Le (Geophysical Technology Research Centre, BGP, CNPC) | Yan, Zhenqian (Sichuan Institute of Coral Field Geological Engineering Exploration and Designing) | Zou, Guoliang (Exploration Department of Changqing Oilfield LTD, CNPC) | Cao, Zhonglin (Geophysical Technology Research Centre, BGP, CNPC) | Zhao, Yao (Geophysical Technology Research Centre, BGP, CNPC)
The Cambrian Longwangmiao Formation in the Sichuan Basin, southwest China, mainly comprising of dolomites, is one of the most ancient production layer in the world. Recently, Anyue gas field was discovered in the Leshan-longnvsi paleo-uplift in the central Sichuan Basin, and become the oldest gas field in the carbonate rocks in a single structural system in China. The reservoir is mainly distributed in the shoal grain dolomite, which is always controlled by the sedimentary environment. The conventional well correlation and sedimentary facies analysis might result in difficulty of carbonate shoals distribution and reservoir description in the gas field. Hence, how to characterize the geometry and distribution of carbonate shoals is critical for gas exploration and development. In our study, we completed an interpretation of 1172km2 3D seismic data in the field by means of all reflectors auto-tracking method. The method, combining density-based spatial clustering with waveform similarity clustering algorithm, can automatically track and interpret all reflectors within the 3D seismic cube. As a result, 18 local horizons, characterized by a shingled progradational configuration, were recognized within the Longwangmiao Formation. Synthetic seismograms suggest that these parallel oblique progradational sets were considered as carbonate shoals. The Longwangmiao Formation is consisted of stacked multistaged carbonate grainstones deposited on the shoals within the platform. These shoals, which grow towards northwest, are approximately distributed surrounding the Leshan-Longnvsi paleo-uplift. Stacked and widely distributed shoal grainstone reservoir is formed on the uplift. Our study suggests that the paleo-uplift mainly controls the shoal distribution in the study area, which provides important clues for gas exploration.
BP is developing the Khazzan and Ghazeer fields of Block 61 in the Sultanate of Oman. The development includes three Cambro-Ordovician tight gas sand reservoirs which require hydraulic fracturing for commercial production rates. There are challenges with depth and high temperature for the open hole logging environment, with a restrictive inner diameter and residual proppant creating challenges for the cased hole logging environment. Additionally, there are cost challenges on all data acquisition including coring, downhole gauges, sampling, proppant tracers and many other forms of surveillance.
This paper outlines the evolution of the data acquisition strategy for the Khazzan and Ghazeer assets. The development plan at project sanction was 20 vertical and 272 horizontal wells. The data acquisition strategy led to the development of a data acquisition plan, and all stakeholders were engaged to ensure the right data was acquired in the right place at the right time. Cross functional behaviours and fiscal discipline were essential in this process. Inclusion of the service companies into the wider BP team was crucial to ensure appropriate technology was applied, learning from previous operations implemented and new technology options made available.
Through careful management of the data acquisition plan, all data in development wells prior to first gas were acquired within the allocated data acquisition budget despite drilling 20% more wells than originally planned for this period. Early improvement in subsurface understanding enabled an overall reduction in well count for the life of the project, extension of the original development into unpenetrated areas, adding significant value to the project.
Levanov, Andrey (TNNC) | Ignatyev, Nikita (TNNC) | Ostyakov, Evgeniy (TNNC) | Vinogradov, Igor (TNNC) | Busuek, Elena (TNNC) | Cherepkova, Anna (TNNC) | Yaschenko, Sergey (TNNC) | Schetinina, Natalya (TNNC) | Semenov, Aleksey (VCNG) | Nesterov, Pavel (VCNG) | Musin, Roman (VCNG) | Dolgov, Igor (VCNG) | Komarov, Andrey (VCNG) | Chirgun, Aleksandr (VCNG)
At present, Russia's oil production in a number of large Eastern Siberia fields (Verkhnechonskoye, Talakanskoye, Yaraktinskoye) has reached or approached its maximum designed levels, therefore, the fields have progressed to the second stage of development or to the beginning of the third stage experiencing production declines. Thus, these fields can be categorized as brownfields. At the Verkhnechonskoye oil and gas condensate field, for the first time in the history of domestic oil and gas production the geologists came across a highly mineralized productive cross-section with the pore space partially or completely filled with salt. This determined the distinctive development features of the main target - the Verkhnechonsky horizon (Vch) (99.8% of the field's production). A distinctive feature of this paper is the description of the approaches to the development of the Verkhnechonsky horizon associated scaling formation and control using a wide range of geological and geophysical tools. The value of the work lies in the summary of lessons learned when managing reserves production and well operation processes at a large Eastern Siberia field, the development of which is complicated by the presence of salts in the pore space, which was the starting point of accumulating the knowledge on salt reservoir development. The experience based on a range of approaches and technical solutions can be applied to similar Eastern Siberia reservoirs with similar geological and physical characteristics.
Zhang, Qiang (PetroChina Research Institute of Petroleum Exploration & Development PetroChina Southwest Oil & Gas Field Company Research Center of Sichuan Basin) | Wang, Shujiang (PetroChina Research Institute of Petroleum Exploration & Development PetroChina Southwest Oil & Gas Field Company Research Center of Sichuan Basin) | Chen, Tao (PetroChina Research Institute of Petroleum Exploration & Development PetroChina Southwest Oil & Gas Field Company Research Center of Sichuan Basin)
The study area is located in the Dazhou-Kaijiang ancient uplift, which is one of three ancient uplifts of Sichuan Basin developed in early Cambrian. The Sinian-Cambrian period has good reservoir forming conditions, and the structure is distributed in lines and belts. However, the fault is very well developed and the structure is complex, so it is difficult to interpret deep seismic reflection characteristics. Meanwhile, under the influence of gypsum rock, the imaging is poor under the gypsum of the high-steep core of anticline, and the structure is not clear. In order to solve the deep Cambrian imaging and structure, firstly, we comprehensively utilized seismic interpretation, forward modeling, seismic attributes and tectonic evolution analysis to establish the structural styles; geological modeling is carried out to guide velocity modeling on the basis of structural styles analysis. We take advantage of model-based tomography and grid-based tomography to optimize velocity model and obtain the imaging under the gypsum rock. This research method not only improves the imaging accuracy under the gypsum and implements the structure, but also provides technical and practical reference for seismic imaging research of other places in Sichuan Basin.
Presentation Date: Thursday, October 18, 2018
Start Time: 8:30:00 AM
Location: 210A (Anaheim Convention Center)
Presentation Type: Oral
The PDF file of this paper is in Russian.
Khoronohskoye license area located within regional zones of the southern Siberian platform has a very complex structure of the sedimentary cover. It is a division of auto - and allochthonous parts. In addition to faulting (microgravity, rift stage, faults, etc.) in the thickness of the subsalt carbonate complex with traces of horizontal formation-thrust deformations that lead to a two-fold repetition in the context of some horizons. Historically, the region of South-Western Yakutia has developed by type of collision passive continental margin. The development took place in four stages, which formed two tectonic complexes. The lower complex (autochthonous) has a block character and it consisted of the rocks of Riphean and Vendian-Cambrian age. The upper complex (allochthon) is a series of tectonic slices, thrust over the platform slope, with an age of the Upper Vendian - Lower Cambrian. The territory with the likes of autochthonous and allochthonous occurrence of the horizon, installed on Khoronohskoye license area. Here in the North-East can be traced long thrust area (thrust), confirmed the drilling data and seismic profiles. The ledge in the relief from Bukskaya suite hindered the promotion of the allochthon in the North-West, which has led to the emergence here of detachment ramp of the allochthon is an abrupt transition of the Vendian salts (Torsalskya bundle) to the level of the Cambrian salts (Ureginskya suite). This has led to the reduction of the thickness Torsalskya salts on the elevations to a complete wedging out, and blown - in depression. Faults of autochthonous determine the prerequisites for the persistence outlier hydrocarbon deposits. In the sediments of the allochthon hydrocarbon deposits can also be, as evidenced by signs of oil saturation in cores and inflows of hydrocarbons on the test results of some wells. With the forecast promising areas special attention should be paid to the sediments of the allochthon, the prospect of which is associated not only with the processes of thrusting, contributing to the emergence of new structures, fractured zones, fluid migration, but also with the availability of depths for drilling.
Территория Хоронохского лицензионного участка, расположенного в пределах краевой зоны юга Сибирской платформы, имеет весьма сложное строение осадочного чехла. Его особенностью является деление на авто- и аллохтонную части. Кроме разрывных нарушений (микрограбены, рифтовые ступени, разломы и др.) в толще карбонатного подсолевого комплекса установлены следы горизонтальных сдвигово-надвиговых деформаций, которые обусловливают двукратное повторение в разрезе некоторых горизонтов. В историческом плане регион юго-западной Якутии развивался по типу пассивной коллизионной континентальной окраины. Развитие шло в четыре стадии, в результате сформировались два тектонических комплекса. Нижний комплекс (автохтон) имеет блоковый характер и сложен рифейскими и венд-нижнекембрийскими породами. Верхний комплекс (аллохтон) представляет собой серию тектонических пластин, надвинутых на платформенный склон и имеющих возраст верхнего венда - нижнего кембрия. Территория с подобным автохтонным и аллохтонным залеганием горизонтов, установлена на Хоронохском лицензионном участке. Здесь в северо-восточном направлении прослеживается протяженная надвиговая зона (шарьяж), подтвержденная данными бурения и сейсморазведочных работ. Уступ в рельефе бюкской свиты препятствовал продвижению аллохтона на северо-запад, что привело к возникновению рампа детачмента аллохтона - скачкообразного перехода вендских солей (торсальская пачка) на уровень кембрийских (юрегинская свита). Это обусловило уменьшению толщин торсальских солей на поднятиях до полного выклинивания и раздуву - в депрессиях. Разрывные нарушения автохтона обусловливают предпосылки к сохранению в нем останцевых залежей углеводородов. В отложениях аллохтона также могут быть обнаружены залежи углеводородов, о чем свидетельствуют признаки нефтенасыщения по керну и притоки углеводородов по результатам испытания некоторых скважин. При прогнозе перспективных зон особое внимание следует обратить на отложения аллохтона, перспективность которого связана не только с процессами надвигообразования, способствующими возникновению новых структур, трещиноватых зон, миграции флюидов, но и с доступностью глубин для бурения.
Geochemical correlations of light oils and condensates represent an analytical challenge because of low concentrations of the longer chain alkanes and polycyclic biomarkers. In this study, several geochemical techniques are shown to be useful tools for the correlation purpose and maturity assessments of condensates from East Siberia. The whole oil GC provides compositional data for a wide range of hydrocarbons (C4-C36) including gasoline range hydrocarbons used to distinguish petroleum families in the study area based on iso-/normal alkane ratios. More unique to the Precambrian petroleum system is a presence of mid-chain methylated alkanes, and their relative concentrations were shown to vary in condensates of the Baykit and Nepa-Botuoba basins. Similar to the previously reported oil samples, condensates in the Nepa-Botuoba Basin are enriched in mid-chain methylalkanes.
The odd/even carbon number predominance in C16-C25 range of alkylbenzenes and alkyltoluenes was also used to differentiate condensates in these two basins. The condensates from the Baykit Basin show a simple slope in C16-C25 range, with almost equal concentrations of odd and even monoaromatic hydrocarbons. The Nepa-Botuoba samples are very different and demonstrate a strong even carbon number predominance in alkylbenzenes and odd carbon number predominance in alkyltoluenes.
Maturity indicators derived from the GC-MS analysis of the aromatic fraction and using distributions of phenanthrene, methylphenanthrenes, dimethylnaphthalenes, methyl-, dimethyl-, trimethyldibenzothiophenes and m-/o-alkyl-toluenes nicely correlate with each other and clearly differentiate overmature condensate from the rest of the group.
The biomarkers findings in a single Verkhnechon sample include predominance of C29 steranes, relatively low diasterane content, very high concentrations of tricyclics vs. pentacyclic terpanes. The biomarkers characteristics along with Pr/Ph <1.0, suggest anoxic depositional environment, predominantly marine algal organic matter source, carbonate lithology of the sources rock, and maturity level corresponding the peak to late oil window. Biomarker distribution in this condensate resembles those of oils discovered in the Nepa-Botuoba Basin suggesting the same source of hydrocarbons in both oils and condensates.
Surprisingly, neither isomer ratios nor absolute concentrations of diamondoids correlate with measured maturity levels in condensates. Additional work has to be done to understand other factors contributing to diamondoid elevated concentrations such as, for example, migration processes.
Commercial-scale deployment of Carbon Capture and Storage (CCS) as a viable greenhouse gas emissions reduction technology requires that the CO2 be confidently contained in geological formations with no risk of groundwater contamination. To ensure containment is adequately monitored, an evaluation of what a potential leak could look like and how it can be detected is required. This paper is an example from the Quest CCS operation in Alberta, Canada.
Quest commenced operation in August of 2015 at a rate of 1 MT/year into two injection wells. After two years of operations, the project’s rigorous monitoring program has demonstrated that the reservoir is behaving as expected and no leaks have been detected. However, hypothetical leak paths have been investigated and modeled. Four scales of models have been used to evaluate the risks associated with the hypothetical leak paths and therefore on containment: (1) Geological structural models - Regional Static Model, Field Dynamic Model, (2) Legacy well - Well Brine Leak Path Model (3) CO2 Leakage - Injection Well CO2 Leak Path Model, and (4) Leak detection - Cooking Lake Model. The results of the modelling were used in the evaluation of the Quest project proposal, the current operating strategy, and the measurement, monitoring, and verification (MMV) plan.
The results of the leak path models demonstrate that the risk of a CO2 leakage from the Quest storage operation is very low. Regional modeling of the overburden confirmed that no leak pathways in the project area could be identified. Field level dynamic modelling demonstrated that injected CO2 is not expected to reach far field legacy wells, but the potential for elevated reservoir pressure displacing saline brine into usable ground water could be a risk if insufficient well count. The impact of a brine leak path was modeled and concluded to be negligible as the overlying under pressured cooking lake formation was concluded to be an effective pressure sink. As the injection wells have the highest pressures and concentrations of CO2 in the reservoir, despite excellent wellbore integrity, they are the most likely location for a theoretical CO2 leak path. It was both concluded that the buoyancy force was a very slow moving affect and that the cooking lake formation ultimately acts as a pressure sink. Therefore, the cooking lake was modeled to understand what pressure response could be expected and whether a leak into those formations could be detected. It was concluded that material leaks at the injection well would be differentiable from baseline pressure drift at the monitoring wells.
Zeng, Hongliu (Bureau of Economic Geology, University of Texas–Austin) | Fu, Qilong (Bureau of Economic Geology, University of Texas–Austin) | Xu, Zhaohui (Bureau of Economic Geology, University of Texas–Austin and RIPED, PetroChina) | Hu, Suyun (RIPED, PetroChina) | Zhao, Wenzhi (RIPED, PetroChina)
Summary In this study, we integrated outcrop, core, wireline-log, and 3D-seismic data in a seismic-sedimentologic workflow to investigate the paleogeomorphology of the carbonate depositional system and its influence on reservoir quality in a deep-buried Cambrian carbonate gas reservoir in Gaoshiti-Moxi field, Sichuan Basin, China. A seismic-paleogeomorphologic map was generated by flattening the 3D seismic volume against a reference event near the study interval. The restored paleo-ramp appears to be a carbonate platform influenced by growth faulting. Core description revealed a porous dolomitized reservoir of platform-margin origin. On stratal slice, porous reservoirs mostly occur at the top of paleo-highlands controlled by growth faults.