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Abstract
Upper Palaeozoic sandstone reservoirs in E' erduosi Basin belong in low-porosity low-permeability ones and reservoir sensitivity evaluation is an important component part of reservoir evaluation. On the basis of collecting these data on thin section, X-ray diffraction, petrophysical property and sensitivity flowing experiment, etc., a research on evaluating Upper Palaeozoic reservoir sensitivity by use of log data was carried out by the authors. First, in light of extracting various parameters closely related to the reservoir sensitivity form log messages, the type of clay minerals in the reservoirs and their content might be quantitatively determined by applying natural gamma ray spectrometry log; and second, through setting up the correlativity between the principal clay minerals and the reservoir sensitivity and treating and examining it by measured data, it was shown that this result was identical to the experimental one. Therefore, in terms of log data, a mathematical relation between the factors influencing reservoir sensitivity and the log data may be set up through calibrating the log data by core analysis data, thus realizing the reservoir sensitivity's being determined by log data.
The Silurian Kepingtage Formation in Tazhong area is regarded as an acid‐sensitive hydrocarbon reservoir. However, formation mechanism of acid‐sensitive of the reservoir cannot be interpreted by the existing acid‐sensitive evaluation criterion based on damage rate. The contents of acid ‐sensitive minerals illustrated by bulk‐rock XRD, scanning electron microscopy and clay mineral composition analysis exert the dominant control on acid‐sensitive flow testing of the reservoir. The iron‐ bearing minerals (including pyrite cements and chlorite cements) mainly deteriorate reservoir quality, while the iron‐free minerals (including calcite cements and dolomite cements) mainly improve permeability. The permeability variation of the tested samples is controlled by the relative content of two acid‐sensitive minerals. On the basis of newly established sensitivity mechanism and its influence on permeability, the corresponding ion (Fe²⁺) stabilizer was added to the acidizing fluids during the acidification reconstruction, which inhibited the negative factors of acid‐sensitive minerals and improved the target layer quality effectively.
As the typical tight sandstones in the eastern Kuqa depression, Jurassic Ahe Formation reservoir is subject to a considerable variety of formation damage. X-ray diffraction and formation damage evaluation of the sandstones samples were tested on the basis of observation in microscope and SEM. Internal factors being responsible for velocity sensitivity, such as cause and content of migration particle and characteristics of pore throat in the reservoir, were analysed. The analysis reveals serious velocity sensitivity in the reservoirs are due to three main controlling factors, including the content of tiny particle result from crash of brittle grain, size and connectivity of pore throat.
In order to determine the affecting factors and to build the predicating model of sensitivity in Luxiang depression, this paper firstly analyzes the sensitivity results and some parameters, including porosity, permeability, contents of different kinds of clay minerals tested in laboratory. Then it analyzes the relationship between sensitivity and porosity, permeability, contents of different kinds of clay minerals, throat type, and the distribution of clay minerals, integrated with the lab methods, such as core casting slices, microscope scanning, etc. Next, parameter prediction models are built by relating with sedimentary facies and depth. The porosity, permeability, contents of different clays, contents of quartz and feldspar were predicted based on these models which were used for sensitivity prediction. At last, sensitivity predicating models are built for speed sensitivity, water sensitivity, acid sensitivity and alkali sensitivity using Elman neural network. Results show that the Elman is efficient in sensitivity prediction; there are strong speed sensitivity, acid sensitivity, alkali sensitivity and salt sensitivity in Wuxing structural zone; whereas there is strong speed sensitivity in the center and northwest of Luxiang depression.
Basing on the chart analysis for clay mineral content, a cross plot of clay mineral content and radioactivity element concentration was obtained, and a multivariate linear relation between clay mineral content and radioactivity element U, Th and K was established, deriving a regression equation to estimate clay mineral content. Through the regression analysis of the data from different well sections or the same well section of different formations, a typical linear regression model was provided. The application of the model to a real well section got a vertical variation of clay mineral, which was in an excellent agreement with the practical interpretations.
Based on the techniques of X-ray diffraction analysis, identification of the thin sections of core cast, physical analysis and scanning electron microscopy analysis, this paper studied the reservoir characteristics of the Carboniferous strata in Donghe well No.1 of Tarim region. The results show that the reservoir lithology is mainly the fine-grained quartz sandstone with ferrocalcite and pyrite, mud cement-based, the permeability concentrated in 5–40 × 10–3 μm2, a small part of the high permeability up to 150–327 × 10−3 μm2 and porosity ranged from 10% to 20%. The most part of the reservoirs is low permeability with a small part of the layer in moderate-high permeability. The types of reservoir space include intergranular pores, intra particle-molding pores, micro-pores and cracks, which mainly are intergranular pores with the pore diameter of 15–200 μm, 95.5 μm on average. And the types of the throats are complex with the main type of constricted throats in this area and large contribution to the permeability.
The use of ionic liquids of the type 1-butyl-3-methylimidazolium aluminium chloride ([bmim]Cl/AlCl3) as catalyst for the synthesis of monododecyl diphenyl oxides has been demonstrated. By using acetonitrile as an IR spectroscopic probe, the Lewis acidity–activity correlation for the ionic liquid catalysts in the alkylation reaction has been studied. A comparative study of the ionic liquids catalyzed system and the traditional AlCl3 system has been carried out and the effects of varying reaction time, temperature, the relative amount and acid strength of the ionic liquids, as well as the molar ratio of diphenyl oxide to α-dodecene have been explored. The yield of the target product with [bmim]Cl/AlCl3 ionic liquids as catalyst for the alkylation of the diphenyl oxide with α-dodecene is much higher than that observed using AlCl3 as catalyst. Furthermore, use of ionic liquids leads to a significant simplification in product isolation, and the system can be regarded as environmentally benign. The maximum yield of the monododecyl diphenyl oxides is about 90% when [bmim]Cl/AlCl3 ionic liquids are used as catalyst under mild reaction conditions. The highest yield is obtained at a reaction temperature of 80°C with a molar ratio of diphenyl oxide to α-dodecene of 7 and α-dodecene to ionic liquid molar ratio of 2. The potential for reuse of the acidic ionic liquids has been investigated. The main cause of deactivation of the acidic ionic liquid was found to be the leaching of the active catalytic species Al2Cl7− as a result of the interaction between the acidic ionic liquid and diphenyl oxide.
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