GeoArabia, Journal of the Middle East Petroleum Geosciences最新文献

{"title":"Origin and occurrence of illite clay mineral in Unayzah Sandstone reservoirs in Central Saudi Arabia. 9th Middle East Geosciences Conference, GEO 2010.","authors":"S. Zaidi","doi":"10.3997/2214-4609-pdb.248.371","DOIUrl":"https://doi.org/10.3997/2214-4609-pdb.248.371","url":null,"abstract":"The Unayzah (Late Permian) sandstone reservoirs in Central Saudi Arabia are important sources of light sulfur-free crude oil and gas. However, the quality of the reservoirs can vary significantly based on the amounts of clay minerals (especially of illite) and quartz cement present in the reservoirs. It has also been observed that illite clay in amounts as little as 2-3 wt% can cause a precipitous decline in the permeability and productivity of a reservoir. In order to evaluate the nature and amount of illite clay in the Unayzah reservoirs, 69 core plugs from 25 wells spanning a depth (temperature) range of 6,200 to 15,500 feet were analyzed by X-ray diffraction (XRD) and environmental scanning electron microscope (ESEM). The results show that illite clay mineral occurs as domains, aggregates, pore linings or infillings, coatings around stable grains, and bridges between grains. Those illite clays can be classified into five types based on petrographic analysis: (1) matrix illite; (2) illuviated illite; (3) illite coating; (4) illite from illitization of kaolinite; and (5) fibrous illite. Types 1, 2 and 3 are detrital in origin whereas types 4 and 5 are diagenetic. \u0000\u0000Among the five types of illite clays, the fibrous illite is more important than others as it is typically diagenetic in nature and grows into pore space during burial diagenesis. The XRD and ESEM results indicate that up to 11 wt% diagenetic illite is present in the cores. However, the data do not show any definite illite trend with depth. The data suggest a large increase in the amount of fibrous illite between 14,000 and 14,500 ft, but then the trend appears to reverse itself below 15,000 ft, where the amount of illite is reduced by 50%. The study revealed that diagenetic illite in Unayzah is mainly related to K-feldspar-kaolinite reaction. However, at shallower depths it appears that the illitization reaction has not gone to completion, which results in non-equilibrium assemblages of illite, kaolinite and K-feldspar. In the samples enriched with detrital illite coatings, although kaolinite is converted to illite, there is still significant amount of K-feldspar present in the rocks. This suggests that detrital clays may be blocking pore fluids from further reaction. It may be possible to predict illite precipitation using a kinetic model based on Arrhenius approach. This will lead to better correlations of illite cement with reduction in porosity and permeability and in identifying potentially good quality reservoirs in areas yet to be drilled.","PeriodicalId":275861,"journal":{"name":"GeoArabia, Journal of the Middle East Petroleum Geosciences","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129199365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neural permeability prediction of heterogeneous gas sand reservoirs. 9th Middle East Geosciences Conference, GEO 2010.","authors":"G. Hamada","doi":"10.3997/2214-4609-pdb.248.004","DOIUrl":"https://doi.org/10.3997/2214-4609-pdb.248.004","url":null,"abstract":"Analysis of heterogeneous gas sand reservoirs is one of the most difficult problems. These reservoirs are usually produced from multiple layers with different permeability and complex formation, which is often enhanced by natural fracturing. Therefore, using new well logging techniques like nuclear magnetic resonance (NMR) or a combination of NMR and conventional open-hole logs, as well as developing new interpretation methodologies are essential for improved reservoir characterization. NMR logs differ from conventional neutron, density, sonic and resistivity logs because the NMR measurements provide mainly lithology-independent detailed porosity and offer a good evaluation of the hydrocarbon potential. NMR logs can also be used to determine formation permeability and capillary pressure. \u0000\u0000This study concentrates on permeability estimation from NMR logging parameters. Three models used to derive permeability from NMR are Kenyon model, Coates-Timer model and Bulk Gas Magnetic Resonance model. These models have their advantages and limitations depending on the nature of reservoir properties. This study discusses permeability derived from Bulk Gas Magnetic Resonance model and introduces neural network model to derive formation permeability using data from NMR and other open hole log data. The permeability results of neural network model and other models were validated by core permeability for the studied wells.","PeriodicalId":275861,"journal":{"name":"GeoArabia, Journal of the Middle East Petroleum Geosciences","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115377598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Estimation of barrel of oil equivalent of gas using PVT multi-stage separation data. 9th Middle East Geosciences Conference, GEO 2010.","authors":"M. A. B. A. B. S. AlBahar","doi":"10.3997/2214-4609-pdb.248.423","DOIUrl":"https://doi.org/10.3997/2214-4609-pdb.248.423","url":null,"abstract":"Over the last sixty years, Kuwait’s gas production has been mainly coming from associated gas sources from its large and thick reservoirs undergoing natural depletion. Recent discoveries of deep Jurassic gas have considerably changed the overall relative make-up of the gas stream. The current gas stream includes gas production from existing oil reservoirs, deep gas reservoirs, condensate, and volatile oil reservoirs. As a result of this, the gas stream is becoming richer. However, in the past there has been no systematic attempt to understand and estimate the barrel of oil-equivalent (BOE) of overall gas based on the relative contribution from the reservoirs in Kuwait. This study is a first attempt to develop a new methodology and process to estimate the BOE factor for Kuwait taking into account all the major oil and gas producing reservoirs in Kuwait. The study considered all gas composition information including PVT test data on all PVT samples for more than 200 wells and gas outlet points. It focused on the gas compositional behavior and the amount of energy associated with different sources of gas. The study shows that any oil company must develop and adopt its own BOE factor for reporting the gas volumes in terms of oil equivalent. Key technical contributions of this work include: data evaluation techniques, estimation of calorific values and conversion of the calorific value to BOE factor (per well, reservoir, field and company), and general correlations of gas and fluid properties for quick projection of BOE value.","PeriodicalId":275861,"journal":{"name":"GeoArabia, Journal of the Middle East Petroleum Geosciences","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116659302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conceptual and numerical modeling of fracture-related high temperature dolomite: Implications for reservoir characterization. 9th Middle East Geosciences Conference, GEO 2010.","authors":"F. Nader","doi":"10.3997/2214-4609-pdb.248.215","DOIUrl":"https://doi.org/10.3997/2214-4609-pdb.248.215","url":null,"abstract":"Classical diagenesis studies make use of a wide range of analytical techniques in order to suggest conceptual models that explain specific, relatively time-framed, diagenetic processes and their impacts on reservoirs. Still, these models are qualitative and do not yield “real” data for direct use by reservoir engineers for rock-typing and geo-modeling. This contribution provides new insights into numerical modeling of dolomitization following two approaches (geostatistical and geochemical transport reactive), and attempts to express the conceptual models of hydrothermal dolomitization which is known to have affected reservoirs in the Middle East, in more quantitative terms.\u0000\u0000A 3-D geostatistical model representing the Ranero dolomitized Cretaceous platform carbonates was constructed, covering an area of 5x2 km and a depth of 2 km. It is based on interpretation of aerial photographs, geological and topographic maps, as well as field observations. The resulting 3-D block included the stratigraphical units, fractures and the dolomite bodies. Geostatistical simulations succeeded in reproducing the dolomitized pattern. A relationship was set to restrict the presence of dolostones to the fractures at depth. A 2-D geochemical transport reactive model was built to represent a high temperature dolomite (HTD) front (ca. 350 m long; cells: 5x1 m) in the Marjaba Jurassic platform carbonates. The nature of the dolomitizing fluid was constrained based on results of fluid inclusions and crush-leach analyses. Two aquifer analogues for the end-members of the mixed dolomitized fluids were chosen according to their similar sedimentological character, mineralogical compositions and ambient temperatures to the expected sources of evaporative marine-related waters and hydrothermal fluids.\u0000\u0000The geostatistical model helped in illustrating the relationships between the hydrothermal dolomite distribution and the fracture pattern. Numerical reactive transport simulations are valuable not only for predicting hydrothermal dolomite texture (porosity/permeability) distribution but also for validating the prescribed dolomitization model. This study provides means to predict fracture-related HTD distribution and related evolved reservoir properties, thereby achieving better reservoir characterization.","PeriodicalId":275861,"journal":{"name":"GeoArabia, Journal of the Middle East Petroleum Geosciences","volume":"130 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132430831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of glaciogenic reservoirs using high-resolution quantitative mineralogical and textural analysis of drill cuttings. 9th Middle East Geosciences Conference, GEO 2010.","authors":"A. Janszen","doi":"10.3997/2214-4609-pdb.248.200","DOIUrl":"https://doi.org/10.3997/2214-4609-pdb.248.200","url":null,"abstract":"In the past decade Palaeozoic glaciogenic deposits in North Africa and the Middle East have been recognised as important reservoirs for hydrocarbons. However, the sedimentary system associated with glaciers and ice-sheets is highly complex and still poorly understood. This often results in large exploration and development risks due to potentially large uncertainties in the reservoir stratigraphy, facies and 3-D architecture. Glaciogenic reservoirs are often associated with deeply incised valleys (i.e. tunnel valleys). These are formed under ice-sheets by overpressured meltwater and can reach up to 600 meters in depth, tens of kilometers in length and 5 kilometers in width. As the sedimentary mechanisms and depositional environments can be highly variable, the subsequent infill of the valleys is vertically and laterally extremely heterogeneous. The heterogeneity of the sedimentary infill often results in problematic subsurface correlation. This is made even more difficult by the absence of biomarkers or marker beds that can be traced on a regional scale. \u0000\u0000Under the Pleistocene ice-sheets of NW Europe, tunnel valleys with similar characteristics to those from the Palaeozoic age were formed. In the city of Hamburg (NW Germany) there is good understanding of the architecture and lithology of the infill of the Pleistocene tunnel valleys due to a database of ca. 17,000 boreholes that were mainly drilled for geotechnical investigations. This study presents the results of a detailed sedimentological and mineralogical study of one of these boreholes. 170 cuttings samples were analysed using QEMSCAN®. This automated instrument uses a combination of backscattered electron imaging and energy dispersive X-ray spectroscopy to mineralogically and texturally quantify samples. Mineralogical and textural trends were identified and correlated with the available wireline logs. Grain-size was compared with the reconstructed density and porosity logs and used to differentiate potential reservoir flow units.\u0000\u0000Mineralogical composition provided an indication of the provenance at different stratigraphical intervals. Diagenetic minerals such as clay and secondary cement infills were also investigated to assess whether such elements could be used for correlative purposes. This study highlighted the compositional heterogeneity of tunnel valley infill and confirmed the potential of QEMSCAN® as a tool to unravel complex stratigraphy and quantify reservoir potential.","PeriodicalId":275861,"journal":{"name":"GeoArabia, Journal of the Middle East Petroleum Geosciences","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133493488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling smectite to illite transformation and the effect on compaction and overpressure development. 9th Middle East Geosciences Conference, GEO 2010.","authors":"Y. Yang","doi":"10.3997/2214-4609-pdb.248.178","DOIUrl":"https://doi.org/10.3997/2214-4609-pdb.248.178","url":null,"abstract":"Smectite illite (I/S) transformation is part of the lithification process of fine-grained sediments. We constructed and calibrated a coupled kinetic I/S transformation and mechanical compaction model in which the Arrhenius Equation describes the rate of transformation and I/S grains collapse. The model accounts for porosity reduction and overpressure development contributed by the I/S transformation. The overpressure contribution results from the transfer of effective stress born by the I/S grains to pore water due to the collapse of I/S grains. The model is controlled by the initial expandable fraction in I/S and the temperature/time history. All together 320 mudstone samples were analyzed by high-quality X-ray diffraction (XRD) analysis for their mineral contents and expandable content in the mixed-layer illite/smectite.\u0000\u0000Below 70°C, I/S transformation barely starts. Our dataset shows that expandable fraction in I/S for the samples with the temperature less than 70°C, that is the value at deposition, can vary from 40 to 100%, a reflection of different sources of I/S. The large variation of expandable fractions in I/S at initial deposition impose difficulties in modeling the I/S diagenesis. We chose a well with a thick homogeneous mudstone section in our model calibration to minimize the effect of the uncertainty of initial expandable fraction. The predicted results from the constructed model agree well with the measured data for the calibration well and also a blind test well. For our dataset, the large range of expandable fraction can be modeled using a different range of initial expandable fractions and reasonable temperature/time histories.\u0000\u0000Since the blind test well has almost the highest initial expandable in I/S and high temperature in the history, we used it to investigate the maximum effect of I/S transformation on porosity and overpressure based on the assumption of no dissipation of overpressure contributed by I/S diagenesis. The maximum porosity reduction is 0.02 and the overpressure only 4 MPa. In reality, the over-pressure contributed by I/S transformation will dissipate and the effect on overpressure will be much less. Our study concludes: (1) the initial expandable content in I/S can vary in very large extent, in the range of 40-100%; (2) our constructed model describes the I/S transformation and its contribution to compaction and overpressure satisfactorily well; and (3) the effect to porosity and overpressure is very limited.","PeriodicalId":275861,"journal":{"name":"GeoArabia, Journal of the Middle East Petroleum Geosciences","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127028138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}