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Exploration, development, structural geology
Summary This study investigates the effect of clay type on the performance variations of steam-assisted gravity drainage (SAGD). Two SAGD experiments at identical experimental conditions were conducted. The reservoir rock for the first experiment (SAGD1) is prepared with a sand (85 wt%) and kaolinite (15 wt%) mixture, and the second experiment (SAGD2) is prepared with a sand (85 wt%), kaolinite (13.5 wt%), and illite (1.5 wt%) mixture. The effectiveness of the steam-chamber growth did not change with the clay type; however, 15-wt% reduction in oil recovery was observed for SAGD2. The possible reasons were investigated with the analyses on the produced-water, the produced-oil, and the spent-rock samples. Contact-angle, particle-size, zeta-potential, and interfacial-tension measurements were carried out on the samples. The mineralogical changes on spent-rock samples were determined by X-ray diffraction (XRD) and scanning-electron-microscope (SEM) analyses. The contact-angle measurements on the spent-rock samples displayed the higher oil-wetness for SAGD2 than SAGD1. However, the water-wetness of illite is known to be higher than that of kaolinite. This unexpected result is explained by the interaction of illite and the asphaltenes from SAGD2. The particle-size measurements, along with the SEM images, on post-mortem samples reveal that illite containing clay exhibits cementation behaviour and, hence, reduces the permeability of the rock. According to the experimental results, we developed hypotheses to understand the bitumen/illite and bitumen/kaolinite interactions for SAGD. Because of the high water-wetness of illite, illite particles first interact with water. This interaction results in cementation and forms illite lumps with sand. Then, illite lumps continue to interact more vigorously with the polar molecules (water, asphaltenes, and resins). Clay migration and production occur in both clay types; however, while kaolinite is produced in the water phase, illite-containing clay as a result of its interaction with asphaltenes is produced in the oil phase.
- Asia (1.00)
- North America > United States > Texas (0.47)
- North America > Canada > Alberta (0.47)
- Research Report > New Finding (1.00)
- Research Report > Experimental Study (0.68)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid management & disposal (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Thermal methods (1.00)
Faster reservoir simulation turnaround time continues to be a major industry priority. Simultaneously, model sizes are reaching a billion cells and the recovery mechanisms and reservoir management processes to be modeled are rapidly changing and are becoming computationally more expensive. A new reservoir modeling solution has been developed to quickly solve these largest and most complex modeling studies within ExxonMobil. With this singular goal to reduce study turnaround time, ExxonMobil has developed its fifth-generation reservoir simulator. This latest generation reservoir simulator has been designed from the ground up with 60 years of internal reservoir simulator development experience.
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (0.34)
- Information Technology > Modeling & Simulation (0.89)
- Information Technology > Software (0.68)
Stratigraphic Expression of Upper Cretaceous Tectonics in the Balambo- Garau Sub-Basin of the Zagros Foldbelt: Implications for Reservoir Presence
Mosola, Amanda B. (ExxonMobil Exploration Company Div. Exxon Mobil Corporation) | Braaksma, Kelley S. (ExxonMobil Exploration Company Div. Exxon Mobil Corporation) | Tai, Po C. (ExxonMobil Exploration Company Div. Exxon Mobil Corporation) | Volkmer, John E. (ExxonMobil Exploration Company Div. Exxon Mobil Corporation) | Grabowski, George J. (ExxonMobil Exploration Company Div. Exxon Mobil Corporation) | Kendall, Jerry (ExxonMobil Exploration Company Div. Exxon Mobil Corporation) | Liu, Chengjie (ExxonMobil Upstream Research Company Div. Exxon Mobil Corporation)
Evaluation of the depositional environments of Upper Cretaceous strata in the Balambo-Garau sub-basin of the Zagros Foldbelt in western Iran into eastern Iraq provides insight into the distribution of reservoir and seal units, as well as potential trapping configurations. Such mapping within the upper sequences of the Cretaceous suggests a larger impact of Proto-Zagros flexure and localized re-activation of deeper seated structural trends in Iraq and Iran. Environment of deposition and unit thicknesses have been mapped and evaluated across western Iran into eastern Iraq using well logs and biostratigraphic data. From the middle Turonian to Santonian, outer-shelf argillaceous limestones overlie proximal to middle- shelf limestones. The deepening of the sub-basin, part of a broader trend of platform carbonates and associated deeper shelf and basinal facies, is concurrent with eustatic sea-level rise, but may also be affected by large-scale Cenomanian-Turonian adjustment. Environmental belts narrow and deposits lap onto highs exposed by localized uplifts as a result of the reactivation of deep-seated structural trends originating in the Permian (or possibly basement?). Outer- to middle-neritic sediments of the Ilam Formation, which onlap local structural highs, are higher quality reservoir facies of ConiacianโSantonian age and, where sealed, may be potential traps. Deposits of the latest Campanian to Maastrichtian also show deepening of lower-shelf and basinal environments within the study area. Non-deposition and onlap of deeper water carbonate wackestone to marls onto highs in the Dezful embayment may further reflect the localized reactivation of deeper seated structural trends. Siliciclastic sediments of the Tanjero Formation shed from highs to the northeast are associated with paleogeographic reversal of the Proto-Zagros, depositing turbidites within the proximal thrust-front basin. Despite time-equivalent prolific oil-producing reservoir intervals in Iraq, ongoing deepening due to the Proto-Zagros Foreland Thrust results in largely non-reservoir marl facies of the Gurpi Formation acting as a seal to the underlying units. The Tarbur Formation, present in the Fars region, consisting of shallow-water rudist grainstone and packstone suggests a lack of accommodation created in association with the Proto-Zagros subsidence event. Tectonostratigraphic trends of the Upper Cretaceous of the Zagros region of western Iran and eastern Iraq show the transition of a relatively quiescent ramp increasingly affected by localized effects of the Cenomanian-Turonian adjustment along with the Maastrichtian inception of Proto-Zagros thrusting and elucidates their impact on reservoir, seal and potential trap distribution within proven and unproven hydrocarbon systems in Iraq and Iran.
- Geology > Geological Subdiscipline > Stratigraphy (1.00)
- Geology > Structural Geology > Tectonics > Compressional Tectonics > Fold and Thrust Belt (0.71)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.53)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock > Limestone (0.47)
- Geophysics > Borehole Geophysics (0.35)
- Geophysics > Seismic Surveying (0.32)
- Reservoir Description and Dynamics > Reservoir Characterization > Geologic modeling (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
Abstract Oil and gas fields encounter issues associated with clay minerals through drilling and production. Depending on the types of clay minerals, they pose the danger of swelling and migration upon exposure to incompatible water. Drilling introduces water through drilling mud, and production introduces water through different treatments such as acid stimulation and hydraulic fracturing. The recovery of oil and gas from subterranean formations has been troublesome in formations that contain water-sensitive minerals, e.g., water-swellable clays, such as clays in the smectite group, and fines capable of migrating when disturbed, such as silica, iron minerals, and alkaline earth metal carbonates. It has been common practice to add salts to the treatment fluids. The salts adsorb to the clay surfaces in an ion exchange process that can temporarily reduce the swelling and/or migration of the clays. Another method used is to coat the area with a polymer in order to physically block the surface of the clays. This paper will mention the types of clays related to the oil industry, describe the structure of clays, mention the mechanisms behind swelling and migrating, and compare the different developments in the field of clay inhibition.
- North America (0.68)
- Asia > Middle East > Saudi Arabia (0.47)
- Geology > Mineral > Silicate > Phyllosilicate (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.48)
Karst Paleogeomorphology Reconstruction of Early Ordovician Carbonate Unconformity and its Petroleum Significance, Tazhong Area, Tarim Basin, West China
Tong, Yanming (Schlumberger) | Zhang, Zhenghong (PetroChina) | Hauser, Ken (Schlumberger) | Xie, En (PetroChina) | Yang, Pin (Schlumberger) | Wang, Peng (PetroChina)
Abstract Karst carbonate reservoir is playing more and more important role in current petroleum industry, and it is the same in study Tazhong area of middle Tarim basin and even the whole basin. Meanwhile, it is noted that paleogeomorphology of carbonate karst unconformity has obvious control on reservoir development and even hydrocarbon accumulation based on many case studies. Therefore, paleogeomorphology reconstruction is often very fundamental but indispensable study for exploration and production activities in such kind of reservoirs. The study carbonate unconformity, i.e. the top of Yingshan formation of early Ordovician, typically occurs at burial depth of 5.2~6.5 km, which is almost the same as that of northern Tarim basin, such as Lungu area. However, there are more challenges here in the work of paleogeomorphology reconstruction for Tazhong area when compared to that for northern Tarim basin: 1) the study carbonate unconformity has much lower relief contrast on paleogeomorphologic micro-unit scale, 2) the overlying formation of Lianglitage is carbonate-dominated and contains many reef-shoal intervals (especially for the upper Lianglitage formation), and 3) the current structure of unconformity horizon seems much different from paleogeomorphology surface. These cause that the often-used methods fail, for example, the paleogeomorphology derived from the whole thickness of overlying Lianglitage formation will be distorted because of higher carbonate production rate at some topographic highs, which is different from a normal clastics case where thicker usually means lower and thinner means higher, like the situation in northern Tarim basin.
- Geology > Geological Subdiscipline > Stratigraphy > Lithostratigraphy (1.00)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.88)
Abstract Polymer flooding is one of the most attractive chemical EOR techniques for sandstone reservoirs however due to complex geological heterogeneity and harsh reservoir conditions its full potential has not been explored in carbonate reservoirs. The main reason behind this limitation is the inability of conventional EOR polymers like HPAM and Xanthan to withstand these conditions. Candidate polymers must provide the required rheology at minimal polymer concentration, be thermally and mechanically stable, and result in a manageable adsorption on the reservoir formation. A polymer screening study has been conducted on a series of polymers, to identify the most suitable candidate that can tolerate the harsh reservoir conditions. Initially, rheological measurements are conducted on a series of polymers followed by filterability, injectivity, static and dynamic adsorption, mechanical and thermal stability testing as a screening criterion for polymers in EOR operations. Amongst the tested polymers polyacrylamide based co- and ter-polymers showed reasonable temperature stability with low salinity tolerance. Whereas, biopolymer Schizophyllan a polysaccharide showed shear thinning behavior with positive thermal stability and salt tolerance. Long-term thermal stability of biopolymer is also conducted at a temperature of 120 ยฐC and salinity up to 220 g/L under anaerobic conditions for over eight months and no viscosity loss is observed. Biopolymer showed acceptable injectivity on cores of permeability more than 30 mD. Core flood effluents viscosity reached 40% compared to injected sample. In addition the mechanical stability and filterability of biopolymer are also discussed. Static as well as dynamic adsorptions of biopolymer have also been studied. The static adsorption on four natural minerals (Calcite, Dolomite, Kaolin, and Silica) as well as formation rocks is reported. Out of these four minerals, maximum and minimum adsorption is observed on Dolomite and Kaolin respectively. The adsorption of biopolymer decreases with salinity and temperature. Adsorption on carbonate reservoir rocks is found to be low when compared to pure calcite and dolomite minerals. Dynamic adsorption on cores with different permeabilites (3 to 165 mD) is measured to be low in magnitude (47.5 to 0.53 ยตg/g).
- North America > United States (1.00)
- Asia > Middle East > UAE (0.93)
- Geology > Mineral (1.00)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock > Dolomite (0.65)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.54)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)
Abstract The petrophysical properties of reservoirs represent several factors such as reservoir quality and volume of oil saturation (PHI, PERM and SW). The relationship between these factors is complementary; migration and trapping of oil is critical to reservoir quality preservation and it is often compromised by closure of the structure, quality of the seal and tectonic activity. In Kuwait, the Mauddud Formation in Bahra Field (BAMA) does not show a sustainable oil production, unlike the Mauddud Formation in Sabriyah Field (SAMA), although both fields are neighboring and separated only by a saddle. Well data reveals a considerable reservoir complexity that distinguishes BAMA from SAMA, which cannot be easily ascribed to facies variability. Geological data (seismic, wireline logs, core and thin sections) indicates four main differences in BAMA compare to SAMA. First, general stratigraphic thinning of carbonate sequences due to its palaeo-proximal position that made it more susceptible to erosion and increased clastic supply and, secondly, a sandier seal rock. Thirdly, there is a degradation of reservoir quality where the average oil saturation and the porosity are 50% and 15% respectively, compared to 90% and 20% In SAMA. Finally, three fault orientations occur in BAMA including a distinct E-W trend, that does not observed in SAMA. Three main possible hypotheses postulated in this study are based on early results. Cementation by meteoric phreatic cements occluded the porosity in BAMA before the arrival of oil. The fresh water penetrations was facilitated by the sandier seal and proximal paleo- environment in BAMA. Onset and partial growth of the trapping structure in SAMA, allowed an earlier oil expulsion to become trapped, retaining secondary porosity, whilst oil bypassed BAMA traps due to later structural growth. The E-W faults in BAMA were responsible for oil migration vertically by breaching the seal rock. The leakage was followed by an influx burial fluids which re-activated cementation in BAMA that was arrested for a short period by the arrival of oil.
- Phanerozoic > Mesozoic > Cretaceous > Upper Cretaceous > Turonian (1.00)
- Phanerozoic > Cenozoic (1.00)
- Phanerozoic > Mesozoic > Cretaceous > Lower Cretaceous > Aptian (0.69)
- Phanerozoic > Mesozoic > Cretaceous > Lower Cretaceous > Albian (0.69)
- Geology > Sedimentary Geology > Depositional Environment (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (1.00)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (1.00)
- (4 more...)
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Seismic Surveying (0.89)
- Asia > Middle East > Saudi Arabia > Arabian Gulf > Arabian Basin > Arabian Gulf Basin > Wasia Formation (0.99)
- Asia > Middle East > Kuwait > Jahra Governorate > Arabian Basin > Widyan Basin > Raudhatain Field > Upper Burgan Formation (0.99)
- Asia > Middle East > Kuwait > Jahra Governorate > Arabian Basin > Widyan Basin > Raudhatain Field > Mauddud Formation (0.99)
- (25 more...)
- Reservoir Description and Dynamics > Reservoir Characterization > Geologic modeling (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Carbonate reservoirs (0.93)
A Study of the Applicability of Bourgoyne & Young ROP Model and Fitting Reliability through Regression
Kutas, D. T. (Montanuniversitaet Leoben - MUL) | Nascimento, A. (Universidade Estadual Paulista - UNESP / PRH48) | Elmgerbi, A. M. (Montanuniversitaet Leoben - MUL) | Roohi, A. (Montanuniversitaet Leoben - MUL) | Prohaska, M. (Montanuniversitaet Leoben - MUL) | Thonhauser, G. (Montanuniversitaet Leoben - MUL) | Mathias, M. H. (Universidade Estadual Paulista - UNESP / PRH48)
Abstract Pre-salt layers has long-term exploration and production possibilities, however the properties of such layers are highly challenging for exploration (i.e. these carbonate layers are highly abrasive, located deeper than 5000 m, have generally low permeability) and production (i.e. pre-salt layers are located in harsh oceanic conditions, hundreds of km offshore). These conditions mean increased exploration technological and economic difficulties. One of the partial solutions to decrease costs is to reduce the drilling operations time. Rate of penetration (ROP) has a significant effect on the overall drilling time, driving ROP modeling and optimization to be a viable solution for reducing drilling operations time in such environment. Several mathematical ROP models were developed in the last five decades in the petroleum industry, departing from rather simple but less reliable R-W-N (drilling-rate, weight-on-bit and rotary-speed) equations until the arrival to a comprehensive and complex approach: Bourgoyne and Young ROP Model (BYM) which was first published in 1974. The paper explains the equation, how it is applied in terms of ROP modeling, identifies the main drilling parameters driving each sub-functions, and introduces how they were developed. The paper base itself on the sub-functions of the equation, explains the normalization factors which have significant influence on the model, and also introduces simulations which aim to understand the approach by applying the equation in a pre-salt layer case study. Knowing that, the original publication was introduced in 1974, this paper also aims to identify rooms for improvement and/or alternate the sub-functions to match actual field data better than with the originally given drillability coefficient recommended boundaries stated in the first publication. This is accomplished through a real-world practical application of this ROP model in a pre-salt layer. The paper also assesses the limitation in terms of the applicability of this complex model for ROP analysis and optimization in such carbonate layers.
- South America > Brazil (0.96)
- North America > United States > Louisiana (0.28)
- North America > United States > California (0.28)
- South America > Brazil > Brazil > South Atlantic Ocean > Santos Basin (0.94)
- South America > Brazil > Campos Basin (0.93)
- Well Drilling > Drillstring Design > Torque and drag analysis (1.00)
- Well Drilling > Drilling Operations (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid management & disposal (0.93)
Abstract A common challenge for the numerical characterization of large Middle East carbonate reservoirs is the potential loss of dynamic fidelity during upscaling. Practical limits for conventional black-oil or compositional simulation using commercial softwares and corner-point geometries restrict reservoir model sizes to a practical limit of few million active cells. For reservoirs with large lateral and/or vertical extent, cell dimensions often exceed tens of feet vertically, resulting in considerable petrophysical averaging compared to wireline log responses. Conversely, static geological descriptions capture log-derived petrophysical contrasts at a vertical resolution of less than two feet. Collocating surveillance responses with log characteristics highlights significant geological elements contributing to conductive and resistive flow responses and is an important initial screening. Optimization of the upscaled layering configuration is the focus of this study, which outlines a practical workflow used to preserve the geological and petrophysical configuration and the dynamic response via targeted sensitivity testing. The analysis was conducted on the 200ft Jurassic Arab D interval of the Dukhan Field in Qatar. The reservoir comprises depositional cycles originating on a shallow carbonate ramp, featuring high frequency sequences (20ft-50ft) of well connected grainstones. Lagoonal wackestone intervals (1ft-5ft thickness) are common and form localized flow barriers. A series of geologically-driven upscale layering scenarios were designed to aggregate stacked conductive grainstone beds, while simultaneously capturing thin baffling carbonate mudstones. Optimization of the fine- to coarse-layer correspondences was achieved using full-field 3D streamline simulation. Upscaled scenarios were screened and benchmarked against the fine scale performance characteristics using layer sweep efficiency as the main optimization criteria. This practical workflow jointly optimizes the geological and engineering upscale layer requirements and facilitates transition to the history match process.
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.55)
- Asia > Middle East > UAE > Arab Formation (0.99)
- Asia > Middle East > UAE > Abu Dhabi > Arabian Gulf > Rub' al Khali Basin > Araej Formation (0.99)
- Asia > Middle East > Qatar > Arabian Basin > Arabian Gulf Basin > Dukhan Field (0.99)
- (9 more...)
Abstract This paper involves integration of data from various sources and of different scales (geology, seismic, borehole logs, cores and dynamic fluid information) which helps to properly characterize a reservoir and to build a reliable static model. Reservoir characterization and modeling are most important part of all aspects related to the field development and also to the exploration. It can help to reduce the risks and to increase resources. It is an important multidisciplinary approach which allows reaching a reliable prediction and a better understanding of our reservoir and its heterogeneities which have a big impact on the fluid drainage. This study consists in characterization and modelling the Triassic reservoirs of Oued Mya basin in order to define the best zones where to drill exploration and appraisal wells. The distribution of the reservoir sands across the field is considered to represent the greatest geological uncertainty in a depositional fluvial environment. The deposition of the Triassic reservoirs occurred in an overall transgressive episode during the Late Triassic as fluvial valley fill and braid-plain quartz sandstones and eolian quartz sandstones. In such a system the channel sand-bodies display extensive heterogeneity and the prediction of net sand distribution is difficult. According to the well logs evaluation those reservoirs are oil bearing in some studied wells, and some others are tight or water bearing situated structurally deeper. The sedimentological model which represents best the environment of our area of study subjected to the modeling would consist of two braided systems.
- Geology > Sedimentary Geology > Depositional Environment > Continental Environment > Fluvial Environment (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (1.00)
- Geology > Mineral (1.00)
- Geology > Geological Subdiscipline > Stratigraphy (1.00)
- Geophysics > Seismic Surveying (1.00)
- Geophysics > Borehole Geophysics (1.00)
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Geologic modeling (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- (2 more...)