The impact of diagenetic processes on petroleum entrapment and recovery efficiency has focused the vast majority of the world's conventional oil and gas resources into relatively narrow thermal intervals, which we call Earth's energy “Golden Zone”. Two key mineralogical research breakthroughs, mainly from the North Sea, underpinned this discovery. The first is the fundamental particle theory of clay mineralogy, which showed the importance of dissolution/precipitation mechanisms in the formation of diagenetic illitic clays with increasing depth and temperature. The second is the surface area precipitation-rate-controlled models for the formation of diagenetic cements, primarily quartz, in reservoirs. Understanding the impacts of these geological processes on permeability evolution, porosity loss, overpressure development, and fluid migration in the subsurface, lead to the realization that exploration and production risks are exponential functions of reservoir temperature. Global compilations of oil/gas reserves relative to reservoir temperature, including the US Gulf Coast, have verified the “Golden Zone” concept, as well as stimulated further research to determine in greater detail the geological/mineralogical controls on petroleum migration and entrapment efficiency within the Earth's sedimentary basins.

Knowledge of mineral composition is helpful in the interpretation of well-logging data, where the hydrocarbon saturation is expected as the final result.It is calculated from the electric resistivity, cation exchange capacity (CEC) and porosity.Porosity is calculated from the bulk density, which is measured directly in the well, and the matrix (mineralogical, grain) density, which can be calculated precisely only when the mineral composition is known.

In the shale-sand formations, which are the subject of this study, the rock matrix can conduct electric current.The Waxman–Smits formula is applied to calculate the water saturation of such rocks.This formula combines rock porosity, water saturation, water resistivity and the CEC with the total rock resistivity measured in the well.CEC is introduced to this formula as the parameter determining the shale ability to conduct electricity.Typically, CEC is controlled by the smectite content of the rock.

In order to evaluate the input data needed in the log interpretation the extended mineralogical (quantitative mineral composition, CEC) and chemical (major, trace and REE) analyses were made for over 200 core samples obtained from four gas fields in the Miocene formation of the Carpathian Foredeep.The most important clay component: the sum of mixed-layer illite-smectite and discrete illite has been quantified.The detailed recognition of clay minerals allowed for constraining the density-neutron cross-plot, which is a well log data interpretation technique for the determination of both porosity and shale content in shale-sand formations.

The statistical multivariate analysis of all data helped to set up a comprehensive petrophysical model.A reliable correlation (r2 = 0.96) of the thermal neutron absorption cross-section (Σama) and the total natural radioactivity (GR) with CEC was established.Such good correlation allows for a continuous on-line CEC determination and therefore a reliable application of the Waxman-Smits water saturation model.Experimental equations with similar level of correlation were established for quartz, clay and carbonate contents, allowing the calculation of matrix density, required in the porosity calculation.

The high correlation of Σama with CEC reflects the presence of boron in the illite-smectite clays.

Microstructural (fabric, forces and composition) changes due to hydrocarbon contamination in a clayey soil (glacial till) were studied using scanning electron microscopy (microfabric analysis), atomic force microscopy (force measurement) and a sedimentation bench test (particle size measurements). Non-polluted and polluted glacial till from NE Poland (in the area of a fuel terminal) were used for the study. Electrostatic repulsive forces in the polluted samples were much lower than in non-polluted samples. In comparison with non-polluted samples, the polluted samples exhibited lower electric charge, attractive forces on approach and strong adhesion on withdrawal. The results of the sedimentation tests indicate that clay particles form larger aggregates and settle out of the suspension rapidly in diesel oil. In non-polluted soil, the fabric is strongly aggregated – dense packing, dominating face-to-face and edge-to-edge types of contacts, clay film tightly adhering to the surface of larger grains and interparticle pores are more common. In polluted soil the clay matrix is less aggregated – loose packing, dominating edge-to-face types of contacts and inter-micro-aggregate pores are more frequent. Substantial differences were observed in the morphometric and geometrical parameters of the pore space. The polluted soil micro-fabric proved to be more isotropic and less oriented than in non-polluted soil. The polluted soil, in which electrostatic forces were suppressed by hydrocarbon interaction, displays more open porosity and larger voids than non-polluted soil, which is characterized by the occurrence of strong electrostatic interaction between the clay particles.

Miocene pelitic sedimentary rocks from six wells in the Sava Depression (sub-basin in the south-western part of the Pannonian Basin System) were investigated in order to determine the degrees of diagenetic alteration.Qualitative and semiquantitative mineral compositions of samples and the content of smectite in illite-smectite (I-S) were determined by X-ray powder diffraction (XRD).Vitrinite reflectance and thermal alteration index (TAI) were measured in order to estimate the palaeotemperatures.Carbonate minerals, clay minerals and quartz are the main constituents of the pelitic sediments.Feldspars (albite), pyrite, opal-CT and hematite are present as minor constituents in some rocks. The mineral composition of the rocks, apart from previously known differences caused by various depositional environments and clastic material provenance, is dependent on the degree of diagenetic processes. At elevated temperatures and large burial depths the minerals formed by alteration processes or precipitated at the surface; smectite, kaolinite and calcite were gradually replaced by minerals formed by diagenetic processes, i.e. by illite-smectite, illite, chlorite, Ca-excess dolomite/ankerite and albite. Based on XRD data for smectite, I-S and illite, three stages of diagenetic development have been established. The early stage was characteristic of samples at depths <1.8 km containing smectite, I-S of the random R0 type and detrital illite.The middle stage begins with the appearance of the ordered R1 type of I-S at the depths >1.8 km and temperature above 80°C. At depths >4.6 km with corresponding temperatures >190ºC, the late stage began, characterized by the presence of R>1 I-S with <10% smectite.

The adsorption of sulphur dioxide (SO2) on two bentonites from Unye, Turkey (Kavaktepe and Yemişlitepe deposits – denoted below as BK and BY) and on forms treated with 1 and 2 M HCl solutions was investigated. The bentonite samples were characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), thermogravimetry (TG-DTG), differential thermal analysis (DTA) and nitrogen adsorption methods. Adsorption capacities of SO2 were obtained using a standard volumetric apparatus at 293 K and 106 kPa. The SO2 adsorption capacity of the BY-2 (1.263 mmol g–1) sample was much greater than the BK-2 (1.126 mmol g–1) sample. As the concentration of acid increased, the specific surface areas and the uptakes of SO2 gas increased.

Bentonite is composed primarily of montmorillonite and is useful in a wide range of applications. This paper presents the results of an experimental investigation carried out to evaluate the possibility of using a Pakistani bentonite (from Jehangira, Swabi District) as a cement replacement material in mortar and concrete. The cement in mortar and concrete was replaced with the bentonite at 0%, 20%, 30%, 40% and 50% by cement mass. The strength activity index of bentonite was determined ‘as received’ (20ºC) and ‘heated’ (treatment at 500ºC and 900ºC). The test results indicated that the strength activity index of bentonite conformed to the ASTM Standard C618 specifications, except for the ‘900ºC heated’ bentonite. The water absorption decreased for mortar containing up to 30% bentonite and then steadily increased at higher bentonite loadings. When immersed in 5% Na2SO4 and 2% MgSO4 solution, the greatest compressive strength was observed for mortar containing 30% bentonite. The water demand of concrete increased with increasing bentonite content. Although the compressive strength of concrete decreased progressively as the substitution level of bentonite was increased, the compressive strength of concrete containing 30% ‘as received’ bentonite was found to be 70% of the control concrete, whereas for concrete containing 30% ‘500ºC heated’ bentonite, the strength was found to be 79% of the control concrete. It can be concluded that this Pakistani bentonite can be used to replace up to 30% of cement to produce concrete with sufficient compressive strength for low-cost construction resistant to sulphate attack.

The aggregation of three cationic dyes (CD), crystal violet (CV), Nile blue (NB) and rhodamine B (RB) in aqueous solution was studied by visible absorption spectrophotometry and compared with methylene blue (MB). The distribution of the dye species (monomers, dimers, trimers, and tetramers) in aqueous solutions with different concentrations of dye was calculated using equilibrium stepwise aggregation constants Kn. These cationic dyes were intercalated into montmorillonite (SAz-1) and its reduced charge form (RC-SAz(210)) prepared by heating lithium montmorillonite (Li/SAz-1) at 210ºC. The fluorescence of fully saturated CD/SAz and low-CD loaded CD/RC-SAz(210) complexes was studied. Visible absorption spectra of CD aqueous solutions and visible absorption spectra and X-ray diffraction patterns (d001) of the CD/SAz and CD/RC-SAz( 210) solid complexes were obtained and evaluated. Large fluorescence intensities were found for CV/RC-SAz(210) and NB/RC-SAz(210) complexes in the same way as for the complex of methylene blue with reduced-charge montmorillonite MB/RCM(210) described previously.

The origin and distribution of late Maastrichtian–early Palaeocene clay mineral associations were investigated in the Tremp-Graus basin (South Pyrenees, Spain) to assess palaeoclimate changes during that period. The studied succession is made up of expanded continental and transitional terrigeneous and carbonate deposits accumulated in a coastal plain setting. X-ray diffraction, SEM-EDX and TEM-AEM analysis reveal that the main clay components are illite and smectite, but kaolinite, chlorite and illite-smectite mixed layers are present, although irregularly distributed, all of them showing a platy morphology typical of a detrital origin. Persistence of the chemical features of the Al-dioctahedral smectites throughout the whole succession demonstrates the persistence of the same source area during the interval studied. Palygorskite occurs in the late Danian and Selandian, within carbonate tidal flats as sabkha-like facies. In SEM images, the palygorskite displays straight fibre morphologies, both coating and branched curling out, a clear proof of authigenic origin.

Physical or chemical weathering (PhW/ChW) determined as illite + chlorite/smectite + kaolinite ratio, smectite/kaolinite ratio and palygorskite distribution have been used as clay proxies for palaeoclimate reconstructions. Such data suggest a shift from temperate subhumid (perennial) conditions in late Maastrichtian times to a warm seasonal climate during early Palaeocene times. This trend, however, was dramatically altered during the late Danian–Selandian interval, when prevailing warm and semi-arid to arid climatic conditions caused intense evaporation and the development of an alkaline environment in which the palygorskite authigenesis took place.

The proposed climatic trend partly concurs with that established for earliest Danian time by Domingo et al. (2007), also in the Tremp-Graus basin, from isotopic and geochemical proxies, as well as with the reconstruction of Cojan & Moreau (2006), in which a semiarid Danian phase for the near continental basin of Aix-en-Provence is postulated. However, it is at odds with the notion of a humid Danian state in the Pyrenees, as inferred by Gawenda et al. (1999) from clay mineral proxies of deep marine successions.

Production of kaolin for the paper-coating industry in the Brazilian Amazon region generates large amounts of waste, most of which is kaolinite. It is known that such materials can be used to synthesize zeolites. The use of kaolin waste for zeolite synthesis could, in principle, help social and economic development while providing valuable materials for industry. Additionally, there is a significant environmental appeal if such wastes could be used instead of new raw materials.

This study focused on the production of zeolite A. Samples of the raw material were first calcined (700ºC/2 h) to obtain metakaolinite for further reaction with NaOH solution. Different parameters were evaluated to optimize the synthesis conditions of zeolite A. The results showed that zeolite A with a large degree of structural order was generally obtained as the only zeolitic product. The following synthesis conditions were used: temperature 110ºC, time 24 h and a Na/Al ratio of 1.36. Hydroxysodalite was also obtained under specific conditions.

Hematite exists ubiquitously in soils and sediments, and is commonly aluminium (Al)-substituted. This study investigated systematically the effects of Al substitution on the visible diffuse reflectance spectrum (DRS) of hematite by using several sets of synthetic samples. We found that the position and amplitude of the characteristic absorption band of hematite (estimated from the first- and second-order derivative curves of the Kubelka-Munk remission function spectrum derived from the DRS) was significantly affected by the degree of Al substitution as well as by sample grain morphology. Therefore, there are ambiguities in quantifying the degree of Al substitution and the mass concentration of hematite using DRS. Nevertheless, if hematite forms under similar environmental conditions, it is possible to establish a transfer function between the DRS parameters and hematite concentration as discussed here for a Chinese loess-palaeosol sequence.

In this study, the reaction between humus acids (humic acid and β-humus fulvic acid fraction) and bentonite and illite was studied at a variety of pH values. The degree of reaction was determined from the specific surface area and molar energy of adsorption. Characteristic parameters of adsorption isotherms for the formation of a mono-layer of the adsorbent, such as the constant C from the BET equation, mono-layer capacity (Nm), and standard error square (R2), were also included in the study. After the addition of humus acids, the specific surface area of illite and bentonite decreased at all pH values, reaching a minimum at pH 4. This indicates different degrees of reaction of humus acids with the clays and, probably, partial hydrophobization of the materials. The degree of reaction of humus acids with the minerals depended on the pH and, for certain combinations, it was highest at pH 4. This value is relatively close to that at which the humus acid fractions in question precipitate from solution.

The purpose of this study was to develop a simple and efficient method for manufacturing porous bioceramics, in which small organic foam spheres were taken as the poremaking reagent and green bodies were made by hot die-casting in moulds. The raw materials (small organic foam spheres, paraffin, oleic acid and β-TCP powder) were mixed into a slurry at 30–120ºC and moulded into green bodies using a hot die-casting machine at 30–90ºC; the green bodies were then sintered and the porous bioceramics obtained. The main characteristics (structure and size of pores, water permeability, apparent porosity and shrinkage) were tested. The results indicated that the apparent porosity was high and directly proportional to the mass ratio between the small organic foam spheres and the β-TCP powder. The pores connected with each other in three dimensions; the size, distribution of the shapes and structures of the pores were clearly related to the dimensions of the small organic foam spheres. The water permeability was proportional to the hot die-casting pressures and the shapes of the samples could easily be controlled by selecting different moulds. This study indicated that the method can be used to manufacture porous bioceramics with controlled pore structures and different shapes effectively and easily by adding different amounts and sizes of small organic foam spheres, mixing the raw materials evenly, and by selection of the hot die-casting pressure and by the use of different moulds.

White clayey geomaterials were collected from northeast of the Nefza region (northern Tunisia). These deposits belong to the Mio-Pliocene molassic basins (basin of Tamra-Sidi Dris, Boukhchiba) and Oligocene Numidien in the area of El Aouinet. Analysis by X-ray diffraction showed associations of halloysite and kaolinite (Tamra), kaolinite and illite (Aouinet zone) and mixed layers, kaolinite and feldspars (Boukhchiba zone). Semi-industrial processed bricks showed promising characteristics and were visibly free of defects. Ceramic tiles had a bending strength that met the required standards but water absorption was somewhat high. So, to achieve higher quality, optimisation needs to be carried out in the formulation of batches or in the processing conditions. Finally, the incorporation in whitish sanitary-ware glaze formulations generated smooth coating layers that showed the required strong brightness and were free of defects.