Zeolite Cement Research Articles

A Comparison of Various Diagenetic Controls by Zeolites on Reservoir Quality: Permian–Triassic Conglomerates, Junggar Basin, Northwestern China

ABSTRACTZeolites are widely distributed in the Permian–Triassic conglomerates of the Junggar Basin and play an important role in reservoir quality. A better understanding of the matching relations between reservoir qualities and zeolitic diagenesis is of great importance for oil exploration in basins. In this study, Permian–Triassic conglomerates from southeast Junggar (SEJ), middle Junggar (MJ), and northwest Junggar (NWJ) were investigated, using casting thin section observations, SEM analysis, EPMA analysis, porosity, and permeability measurements. The Permian–Triassic conglomerates of all three areas have abundant volcanic lithics. The conglomerates from NWJ and MJ contain higher contents of sedimentary lithics and feldspars than those from SEJ. Zeolites of SEJ and NWJ originate from the alteration of volcanic lithics, occurring as pore filling in stage B of eodiagenesis. The zeolitic diagenetic process of SEJ is volcanic lithic–clinoptilolite–analcime–heulandite–laumontite, while that of NWJ is volcanic lithic–analcime. Zeolites of MJ originate from albitization of plagioclase, occurring as pore filling and replacement in stage A of mesodiagenesis. Its diagenetic process is a replacement of plagioclase by laumontite. Diverse zeolitic diagenesis played different roles in reservoir quality. Zeolite cementation and compaction both destroyed the reservoir qualities of SEJ and NWJ. In MJ, the reservoir quality was mainly destroyed by compaction, resulting in strong heterogeneity. In later diagenesis, the dissolution of zeolite cements improved reservoir qualities. SEJ is located farther from hydrocarbon generation sags than NWJ and MJ. As a result, zeolite dissolution pores are poorly developed in SEJ. Previous research has revealed that analcime dissolves more easily than laumontite. Zeolite dissolution pores developed better in NWJ than in MJ. In comparison of the conglomerates with zeolite dissolution pores in the Junggar Basin, NWJ conglomerates have the best reservoir quality, indicating that zeolitic diagenesis can provide implications for oil exploration in the Junggar Basin.

Improving the strength and reliability of mortar composites with zeolite substitution

Clinoptilolite zeolite, a naturally occurring pozzolan, is a viable supplemental cementitious material (SCM) for reducing the carbon footprint generated by the cement industry. While previous literature has explored the use of natural zeolite as an SCM for cement composites, this investigation advances understanding on the effectiveness of natural zeolites as an SCM in three phases. In Phase I, two distinct forms of zeolite (Z1 and Z2) in relative mineralogical compositions and particle sizes were incorporated into mortar composites to replace ordinary Portland cement (OPC) at concentrations up to 20 wt% and characterized over a period of 28 days. Based on the superior performance of the higher clinoptilolite content zeolite (Z2), it was used in Phase 2 to evaluate the effect of zeolite substitution. In Phase 3, the reliability of the resultant composites prepared with Z2 were assessed using Weibull statistics. The inclusion of Z2 type zeolite at #200 mesh size and 10 % concentration yielded compressive strength and reliability comparable to the OPC control mortar at day 7, but significantly greater strength and reliability from day 14 onward. Porosity detailed by microCT suggests that increasing zeolite content to 15 % and greater results in unreacted zeolite that is detrimental to strength. The findings further establish the merits of natural zeolite as an SCM material and distinguish what is necessary for further improvements in mechanical properties of zeolite cement composites.

Controlling Factors of Dissolution Pores in Zeolite Cements of Permian Clastic Rocks in Northwest of Junggar Basin

Abstract Zeolite cement dissolution pores, buried at a depth of over 3600 meters, are found well developed in clastic rocks of Permian in northwest of Junggar basin. Studying the controlling factors of zeolite cement dissolution pores have important meaning to predict the distribution of favorable reservoirs in deep oil and gas exploration of Permian. A comprehensive research method of thin slice analysis of 800 pieces of castings from 60 wells, core observation, scanning electron microscopy, and clay mineral analysis was adopted. It is believed that the dissolution pores of zeolite cements are mainly controlled by zeolite distribution, the scale and range of inorganic and organic acids. Firstly, different zeolite cement types appear a regular pattern that control dissolution pore types and their distribution scope. The study area are well developed three types zeolite cements: heulandite, analcite and laumontite. The heulandite cements are developed in basin edge, showing a belt-like distribution, and then the analcite distribution area. laumontite cements are distributed in basin central. Horizontally in basin edge, reservoir pore type is primary intergranular pore, and followed by analcite dissolution pore. In central basin, the major pore type is laumonitite dissolution pore, and followed by primary intergranular pore. No heulandite dissolution pores are found in study area. Secondly, analcite dissolution pores, formed by inorganic acid and distributed in basin edge, are controlled by the scale of stratigraphic unconformities and faults. Laumonitite dissolution pores, formed by organic acid and developed in central basin, are controlled by the scope of source rock. Thirdly, it is proposed that the meddle-belt of basin is the favorable zone for Permian reservoirs because it is located fan delta front where the laumontite cement is developed, close to the source rock, and in the updip direction of the three stages of organic acid migration. It is considered that central basin has favorable conditions to form laumontite dissolution pores, and pointed out that this zone is a favorable zone for the development of deep reservoirs in the Permian.

Diagenetic effect on reservoir quality of siliciclastic and volcaniclastic sandstones from a Paleogene volcanic rifted margin, East Greenland

ABSTRACT Siliciclastic and volcaniclastic sediments in a volcanic rifted-margin succession may experience a complex diagenetic history during burial that can have a large impact on sandstone reservoir properties. To understand such changes, variations in initial sediment composition and succeeding diagenetic changes have been studied for a Paleogene outcrop analogue in the Kangerlussuaq area, East Greenland. The nature of the mafic volcanics-bearing succession, which consists of intra-volcanic sandstones, accommodated over quartz-rich pre-volcanic fluvial sandstones, are comparable to the settings of recently discovered hydrocarbon-producing sandstones in the Faroe–Shetland Basin on the conjugate Atlantic margin. Our petrographic and provenance investigations of the pre- and intra-volcanic sandstones are supported by geochemical and X-ray diffraction analyses. The intra-volcanic sandstones were deposited in shallow marine environments with mixed siliciclastic and volcaniclastic input, the latter rich in felsic to mafic volcanic rock fragments and feldspar grains. Similar zircon age distributions of pre- and intra-volcanic sandstones support a continued supply from the same siliciclastic sediment source after the onset of volcanism. Variations in initial detrital grain and pore-fluid (fresh to marine) compositions resulted in different diagenetic changes in the pre- and intra-volcanic sandstones. However, where siliciclastic sandstones were overlain by volcaniclastic rocks rather than massive lava flows, the diagenetic changes resemble those of the intra-volcanic sandstones. The cementing phases are typically quartz, illite (probably illitized kaolinite), and rare anatase in the pre-volcanic sandstones. Chlorite, calcite, zeolite/feldspar, opal/quartz, and titanite are characteristic authigenic phases in the intra-volcanic sandstones. Precipitation of different minerals in the pre- and intra-volcanic sandstones show that the detrital composition (and to a lesser extent depositional environment) played a major role during early and late diagenesis after deep burial (up to 6–8 km). Inter-eruptive siliciclastic units may prove to form highly valuable reservoirs when they are composed of mixed siliciclastic and volcaniclastic material. In the stratigraphically youngest intra-volcanic sandstones and pre-volcanic sandstones overlain by hyaloclastite or tuff, there is a high potential for preservation of interparticle porosity during burial (< 5 km) due to early chlorite rims and the generation of secondary porosity after the dissolution of early zeolite cement.

The Effect of Natural and Synthesised Zeolites on Cement-Based Materials Hydration and Hardened State Properties.

The synthesis of zeolites from difficult-to-utilise waste materials facilitates the creation of more financially attractive and efficient synthetic zeolites. These can be incorporated into construction materials, resulting in a reduction in cement usage and the production of superior, clean, and sustainable construction materials. The potential to enhance the hydration rate of fresh cement paste by substituting up to 10% of the cement with two synthetic zeolites-one commercially produced and the other synthesised from waste and natural zeolite-was explored. Due to a higher Al/Na ratio, newly sintered waste-based zeolite possesses six times higher electrical conductivity compared to industrially produced 4A zeolite and more than 20 times higher electrical conductivity compared to natural zeolite. As the sequence of this fact, substituting up to 10% of the cement with AX zeolite cement paste accelerates the maximum heat release rate time and increases the total heat by 8.5% after 48 h of hydration. The structure, compressive strength, and water absorption of the hardened cement paste depends on the Al/Na ratio, pH, and electrical conductivity values of the zeolite used. The findings revealed that AX zeolite, due to presence of mineral gibbsite, which speeds up hydration products, such as CSH development, increases the compressive strength up to 28.6% after 28 days of curing and reduces the water absorption by up to 1.5%. Newly synthesised waste-based AX zeolite is cheap because its production is based on waste materials and is mostly promising due to superior properties of created construction materials compared to the other presented zeolites.

Effects of Waste Cement on the Extractability of Cd, Soil Enzyme Activities, Cadmium Accumulation, Activities of Antioxidant Enzymes, and Malondialdehyde (MDA) Content in Lettuce

Waste cement, a common by-product of urban construction, is often wasted in huge quantities and is worthless. However, some studies have confirmed that waste cement can be used as an alternative heavy metal immobilizing agent. Waste cements, derived from hydrated cement mortar products, were evaluated for soil Cd bioavailability by DTPA extraction and for their efficacy in ameliorating the toxicity of cadmium to soil enzymes and plant antioxidant enzymes. Soil incubation and pot experiments were conducted on three types of waste cement (OPC (ordinary Portland cement), FAC (fly ash cement) and ZEC (zeolite cement)) with an application rate of 1%, 2%, and 3%. The addition of OPC, FAC, and ZEC significantly increased the pH and cation exchange capacity of the soil (p < 0.05). The concentration of DTPA-extractable Cd significantly reduced with a consequential decrease in Cd uptake and transport in lettuce. OPC, FAC, and ZEC application significantly (p < 0.05) enhanced FDA hydrolysis and soil urease activity, except for catalase activity. OPC, FAC, and ZEC, when applied to soil, enhanced the total dry biomass (shoots and roots). Furthermore, the activities of guaiacol peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD) declined in lettuce treated with OPC, FAC, and ZEC. With the addition OPC, FAC, and ZEC, the content of MDA in lettuce leaves displayed a remarkable decrease. In conclusion, the waste cements effectively reduced Cd bioavailability and enhanced the antioxidant system of lettuce.

Volcanoclastic and epiclastic diagenesis of sandstones associated with volcano-sedimentary deposits from the upper Jurassic, Lower cretaceous, Paraná Basin, southern Brazil

The opening of South Atlantic Ocean produced an immense volume of lava that covered an active aeolian system during Lower Cretaceous. The contact of Botucatu Formation sandstones with the Serra Geral volcanic flows generated a variety of volcano-sedimentary features and deposits. During volcanism, the temperature contrast between lava and wet or water-saturated sediments formed volcanoclastic features and related sedimentary deposits. In moments of magmatic quiescence, epiclastic deposits were generated due to the return of sedimentation. Volcanoclastic deposits include volcanic breccias with sandy matrix, and epiclastic deposits include conglomerates and conglomeratic sandstones with intraclasts. Quantitative petrography of the sandy matrix samples of these deposits was analyzed, in order to discuss the paragenesis of volcano-sedimentary interactions. Regular burial diagenetic processes were discussed for epiclastic sandstones and contact diagenesis processes for volcanoclastic sandstones. The original composition of volcanoclastic and epiclastic sandstones is heterogeneous. However, the main difference between them is the presence of textural fluidization indicators found in the volcanoclastic sandstones, along the lava-sediment interface. These textural characteristics indicate that the unconsolidated sediments were probably wet or saturated in water during the interaction with the volcanic flow. Epiclastic sandstones have infiltrated clays and neoformed smectites as their main diagenetic constituent due to alteration of available volcanic lithoclasts. For volcanoclastic sandstones, the formation of opal, chalcedony and megaquartz cements through burial is unlikely, due to the intergranular volume occupied by these cements, indicating near-surface early diagenetic conditions. Therefore, the mechanisms of dissolution and repreciptation of the siliceous fluids, incorporated in the system, formed mainly the chalcedony cementation. Furthermore, zeolite cementation, which occurs along the lava-sediment contact, is another important indicator of contact diagenesis for volcanoclastic sandstones. During telodiagenesis, the formation of secondary porosity by dissolution of volcanic lithoclasts and detrital K-feldspar grains was of great importance in volcanoclastic and epiclastic sandstones.

Quantitative assessment of the effects of zeolite alteration processes on deep clastic reservoirs – A case study of the Jiamuhe Formation in the Shawan Sag, Junggar Basin, China

Zeolite minerals are widely developed in clastic rock reservoirs around the world, and their behavior during diagenetic evolution affects the performance of the reservoirs. Zeolite can fill the primary intergranular pores in a cemented manner and can also undergo alteration and postdissolution to increase pores during the diagenesis process, while quantitative research is still quite limited at present. For this purpose, this paper takes the typical zeolite-rich Jiamuhe Formation (P1j) in the deep layer of the Shawan Sag, Junggar Basin, as an example and carries out a series of sedimentological, petrological, mineralogical and geochemical analyses to quantitatively evaluate the effect of zeolite alteration on the reservoir. The results indicate that the deep P1j reservoir contains fan-delta facies sandstone and conglomerate, and its storage space is mainly zeolite intercrystalline pores and remaining intergranular pores. The zeolite mineral type is almost all laumontite, with very low analcite and heulandite contents (<1%). The volcanic glass provided by the medium–basic volcanic rock debris (andesite and corresponding tuff), with the continuous increase in temperature and the supply of alkali metal ions, is eroded into laumontite via clinoptilolite and heulandite. In the process of zeolite alteration, zeolite minerals appear as zonal characteristics in the vertical direction. The intercrystalline pores formed by the dehydration of zeolite minerals are the most important factors for the development of high-quality deep reservoirs. Based on a large number of statistical analyses of zeolite cementation and intercrystalline pores within the cementation, a unit change of zeolite can cause a unit change in the intercrystalline pores of 22.16%. Supposing that the laumontite mineral content of the reservoir is 30%, the porosity can be increased by 6.6%. This can provide theoretical guidance for the change in the porosity of zeolite alteration in zeolite-rich reservoirs under similar backgrounds and improve the academic understanding of this point, which is exceedingly crucial. For instance, the Permian sand-conglomerate reservoirs in the northwestern margin of the Junggar Basin also have similar zeolite alteration pathways, and the porosity can be quantitatively increased by 8.8% (the zeolite cementation is approximately 40%). Laumontite (21%) in high-quality reservoirs of the Yingcheng Formation in the Changling Sag, Songliao Basin, can increase the porosity by 4.5%.

The secondary pore development model of coarse-grained deposition: A case study of the Xiazijie Formation in the Northwestern Margin of the Junggar Basin

The coarse-grained glutenite rock mass of the proximal fan delta is characterized by the blocky texture, mixing of gravels with varied sizes, high mud content, and low porosity and permeability, leading to difficulties in assessment and exploration of oil and gas enrichment regularities of tight glutenite. The Permian Xiazijie Formation in the northwest margin of Junggar Basin has a set of tight glutenite reservoirs, and the reservoir quality is an important controlling factor for oil and gas enrichment. Based on three-dimensional earthquake, casting thin sections, rock physical property, geochemistry, the sedimentary facies division, petrologic features, physical property regularities, pore types and diagenesis of Xiazijie Formation were analyzed. This research develops the pore evolution model of the coarse-grained deposition via the quantitative analysis of porosity evolution. First, during the rapid compaction, intensive mechanical compaction results in reduction of the original porosity from 29.8% to 15.1%. Secondly, the cement formed during the eodiagenesis destructs the reservoir space and leads to an average porosity loss of 6.5%. Third, dissolution effectively improves reservoir quality. It mainly dissolves the zeolite cement, and the porosity grows to 12.1% from 8.6%. The dissolution occurs during the main hydrocarbon expulsion stage of the source rock, which is in favor of hydrocarbon emplacement. Fourth, during the telodiagenesis with the deepening burial and intensifying pressure solution, siliceous and carbonate cement precipitate, the reservoir physical property is degraded again, the porosity loss is about 3.4%. After a series of complex diagenetic processes, the current tight glutenite reservoir comes into being, with the porosity of about 8.7%. The research results provide theoretical reference for coarse-grained glutenite reservoir prediction.

Coupling Relationship between Diagenesis and Hydrocarbon Charging in Middle Permian–Lower Triassic in the Eastern Slope of Mahu Sag in Junggar Basin, Northwest China

In this study, a variety of test and analysis methods, such as cast thin sections, fluorescent thin sections, scanning electron microscopy, fluid inclusions, etc., were comprehensively used and combined with logging data, sedimentary systems, burial history and other research results, to systematically study the diagenesis characteristics of Middle Permian Lower Wuerhe formation–Lower Triassic Baikouquan formation reservoirs and their control on hydrocarbon accumulation. The coupling relationship between the hydrocarbon accumulation process and reservoir secondary pores was established. The result shows that besides the development of primary intergranular pores, the reservoir develops secondary pores, such as particle dissolution pores, cement dissolution pores and fractures. The development of secondary dissolution pores, such as particle dissolution pores, carbonate and zeolite cement dissolution pores, is mainly controlled by the range and scale of organic acids produced by the thermal evolution of source rocks. It is considered that being located in the updip direction of source rocks, being involved in the development of the unconformity surface and the faults connecting source rocks, and being involved in the development of alkaline cements (such as laumontite) are the three dominant conditions for the development of secondary dissolution pores in the study area.

Zeolite-Enhanced Portland Cement: Solution for Durable Wellbore-Sealing Materials

Wellbore-plugging materials are threatened by challenging plugging and abandonment (P&A) conditions. Hence, the integrity and resilience of these materials and their ability to provide sufficient zonal isolation in the long-term are unknown. The present work focuses on investigating the potential to use zeolites as novel additives to the commonly used Class-H cement. Using four different zeolite-cement mixtures (0%, 5%, 15% and 30%, by weight of cement) where samples were cast as cylinders and cured at 90 °C and 95% relative humidity, the unconfined compressive strength (UCS) testing showed a 41% increase with the 5% ferrierite addition to the Class-H cement in comparison to neat Class-H cement. For triaxial compression tests at 90 °C, the highest strength achieved by the 5% ferrierite-added formulations was 68.8 MPa in comparison to 62.9 MPa for the neat Class-H cement. The 5% ferrierite formulation also showed the lowest permeability, 13.54 μD, which is in comparison to 49.53 μD for the neat Class-H cement. The overall results show that the 5% ferrierite addition is the most effective at improving the mechanical and petrophysical properties based on a water/cement ratio of 0.38 when tested after 28 days of curing in 95% relative humidity and 90 °C. Our results not only demonstrate that zeolite is a promising cement additive that could improve the long-term strength and petrophysical properties of cement formulations, but also provide a proposed optimal formulation that could be next utilized in a field trial.

Effects of cementation on physical properties of clastic rock-originated weathering crust reservoirs in the Kexia region, Junggar Basin, NW China

Cements are widely developed in clastic rock-originated weathering crust (CWC) reservoirs in the Kexia region along the northwestern margin of the Junggar Basin and significantly affect reservoir physical properties and oil and gas distribution in this area. Focusing on the CWC reservoirs at the top of both the Permian Jiamuhe Formation and the Triassic Karamay Formation, this study analyzed the types and characteristics of cements in the reservoirs and explored their effects on reservoir physical properties based on thin sections, SEM images, XRD results, and tests of physical properties. The main results are as follows. The cements in the CWC reservoirs in Kexia region mainly consist of carbonate minerals (41.5%), clay minerals (27.8%) and zeolite minerals (30%), as well as small amount of siliceous minerals. Among them, the carbonate minerals are dominated by siderite and calcite, the clay minerals mainly include kaolinite, interstratified illite/smectite (I/S) and chlorite, and the zeolite minerals primarily comprise heulandite and laumontite. These different types of multiphase cements are generally paragenetic or associated and affect reservoir physical properties to different degrees. Specifically, the carbonate and clay cements of the early diagenetic stage reduced the reservoirs’ average porosity from 21% to 15%. The dissolution of some carbonate and zeolite cements in the early A substage of the middle diagenetic stage restored the average porosity to 18%, and the cementation in the late A substage decreased the average porosity to 13% again, of which about 4% was reduced by carbonate cements. The average porosity of the CWC reservoirs gradually decreased to the current value of approximately 10% in the B substage of the middle diagenetic stage. The impact of cementation on the CWC reservoirs can reach as far as 70 m below the unconformity. Moreover, the types and contents of cements vary with their depth below the unconformity surface, leading to the development of multiple zones with high cement content and the differentiated oil and gas distribution.

Restoration of Reservoir Caprock: Long-Term Wellbore Sealing and Abandonment through Zeolite Enhanced Cement.

Oil and gas wellbores that are drilled into the earth’s crust need to be plugged and abandoned, to restore the geological seals once they are no longer producing. The main aim of Plugging and abandonment (P&amp;A) is to ensure that there is no leakage of hydrocarbons into the environment. Since offshore P&amp;A is challenging due to subsurface temperature and pressure conditions, testing zeolite as an additive for improvement of cement properties is an intriguing research topic. This initial research aims to establish the chemical properties of zeolite when added to cement to hypothesize the mechanism of cement property enhancement. This work consists of the initial results in which the microstructural characterization of a naturally obtained zeolite ferrierite (FER) was done to compare it with the existing observations from the literature. Ferrierite was observed to have a needle like orthorhombic crystal structures and spherical crystal aggregates. The chemical composition was confirmed through EDS studies as it is made up of aluminum silicate crystals and proof was shown that the zeolites maintained chemical stability in the cement matrix even after hydration. Morphological characterization also showed features that indicated possible self-healing in commercial zeolite cement formulations used for geothermal wells, which was studied as a reference. The phase stability was indicated by XRD studies with ferrierite peaks observed at 2θ values of 25.195 and 25.5204 and it was differentiated in comparison to plain Class-H cement which did not have those peaks. A preliminary strength testing had also shown an improvement in 5% FER added Class-H cement in comparison to 15% and 30% FER added Class-H cement formulations which is promising for further studies.

Reservoir Quality Assessment Based on The Occurrence of Burial Diagenesis: Sandstone Case Study From Tanjung Formation, Barito Basin, South Kalimantan

Barito Basin is known as one of hydrocarbon producing basin which is located in the Southeast Kalimantan. One of its prolific reservoir comes from sandstone facies of Tanjung Formation in the Paleo-Oligocene time. The sandstone undergone diagenesis, subsequently after deposition due to burial process. Burial diagenesis promotes further compaction, cementation and alteration which affect the reservoir quality. This study aims to assess the reservoir quality and its sensitivity against the diagenesis products. Research method was carried out by examine the core samples and scrutiny laboratory observation, such as Scanning Electron Microscope (SEM). X-ray Diffraction (XRD), porosity, permeability, grain density measurement and surface gamma-ray. The results show that the amount and type of alteration is vary by depth, age and lithofacies. Sandstones of sublitharenites and litharenites were buried to depths of 848.29 – 849.80 m and contained significant amounts of authigenic grain-coating and pore-lining clay as well as pore-filling zeolite cements. However, the underlying sandstones from 969.19 – 970.14 m depths exhibit less extensive alteration. In the early burial process, the reservoir quality is modified by the formation of secondary dissolution pores and minerals as a result of silicate dissolution during shallow burial diagenesis. The subsequent burial has reduced the pore spaces through mechanical compaction and cementtion. This study certainly valuable addition to our understanding about reservoir quality in correspond to the burial diagenesis.

The Effects of Waste Cement on the Bioavailability, Mobility, and Leaching of Cadmium in Soil.

Waste cement is a construction and demolition waste produced from old buildings’ demolition and transformation. In recent years, the recycling of recycled concrete is limited to the use of recycled aggregate, and the research on the utilization of waste cement in waste concrete is scarce. This study explored the effective application of waste cement for the adsorption of cadmium (Cd2+) from an aqueous solution and the bioavailability and immobility of Cd2+ in soil. Results showed that the maximum adsorption capacities of ordinary Portland cement(OPC) paste, fly ash cement (FAC) paste, and zeolite cement (ZEC) paste for Cd2+ were calculated to be 10.97, 9.47, 4.63 mg·g−1, respectively. The possible mechanisms for Cd2+ adsorption in the solution by waste cement mainly involve precipitation by forming insoluble Cd2+ compounds in alkaline conditions, and ion exchange for Cd2+ with the exchangeable calcium ions in waste cement, which were confirmed by XRD and SEM. Results from diethylene triaminepentaacetic acid (DTPA) extraction and toxicity characteristic leaching procedure (TCLP) implied reduction of the Cd2+ mobility. DTPA-extractable Cd2+ decreased by 52, 48 and 46%, respectively, by adding 1% OPC, FAC and ZEC. TCLP-extractable Cd2+ decreased by 89.0, 80.3, and 56.0% after 1% OPC, FAC, and ZEC treatment, respectively. BCR analyses indicate that OPC, FAC, and ZEC applications increased the percentage of Cd2+ in residual fraction and induced a high reduction in the acid-soluble Cd2+ proportion. The leaching column test further confirmed a reduction in Cd2+ mobility by waste cement treated under continuous leaching of simulated acid rain (SAR). Therefore, waste cement exhibited a significant enhancement in the immobilization of Cd2+ under simulated acid rain (SAR) leaching. In summary, the application of alkaline waste cement could substantially remove Cd2+ from wastewater and reduce Cd2+ mobility and bioavailability in contaminated soil.

Characteristics of dissolved pores and dissolution mechanism of zeolite-rich reservoirs in the Wuerhe Formation in Mahu area, Junggar Basin

The reservoir in the Wuerhe Formation in the Mahu Sag, northwestern Junggar Basin, China, exhibits complex dissolution and cementation related to zeolite. The source and mechanism of diagenetic fluids are crucial in studying the reservoir genesis. Thus we investigated the key reservoirs fluids related to the zeolite and discussed their significance in the zeolite-rich reservoir of the Permian Wuerhe Formation in the Mahu Sag. Based on thin sections and electron microscope observations of rock samples and analyses of physical properties, C-O isotopes, and major elements, it is found that the reservoir underwent mainly two stages of fluid-related dissolution and cementation processes, in which the hydrocarbon-bearing fluid played the primary role in forming the high-quality reservoir. Dissolution pores are the most important storage space, and zeolite cement is the most important dissolution mineral. The geochemical characteristics of zeolite and calcite cement indicate the presence of two diagenetic fluids. The iron-rich calcite and orange-red heulandite is related to early diagenetic fluids with high iron content and higher carbon isotope values, whereas the calcites, with high manganese content and lower carbon isotope values, are formed by late acidic organic diagenetic fluids related to oil and gas activities. The hydrocarbon-bearing fluids form different spatial diagenetic zones, including the dissolution zone, buffer zone, and cementation zone, and the dissolution zone near the oil source fault is the main site of zeolite dissolution. The late fluid has the characteristics of multi-stage activity, which makes the spatial zoning expand gradually, resulting in multiple superpositions of dissolution and cementation and increasing the complexity and heterogeneity of the reservoir diagenesis. This study expands the understandings of the dissolution activities of different fluids in zeolite-rich reservoirs and also has reference significance for dissolution activity of hydrocarbon fluid in other types of reservoirs.

EOCENE VOLCANICLASTICS IN THE KARTLI BASIN, GEORGIA: A FRACTURED RESERVOIR SEQUENCE

In the broader Caucasus region, multiple extrusive volcanic units are present within the Jurassic, Cretaceous, Eocene and Miocene sedimentary successions. Partial reworking of volcanic material from various provenance areas into Eocene, Oligocene and Miocene reservoir units is commonly observed in the Eastern Black Sea and in the Rioni, Kartli and Kura Basins of onshore Georgia. Reservoir quality has in general been negatively affected by volcanic rock fragments which may have undergone complex diagenetic alteration. However, despite concerns regarding reservoir quality, oil at the Samgori field, the largest field in Georgia (∼200 MM brl recovered), is hosted in altered Middle Eocene volcaniclastic sandstones interbedded with deep‐water turbidites. Previous studies of core material from numerous wells in this field showed that most of the oil is contained in altered, microfractured, laumontite‐rich tuffs which have fracture and cavernous net porosities averaging 12% and average permeability of 15 mD. The laumontite tuffs comprise only up to 20% of a tuffaceous sandstone section and occur as isolated lenses or pods on a sub‐seismic scale (i.e. 5‐10 m thick), causing highly variable oil productivity from one well to another.The petrographic analysis of samples of Middle Eocene volcaniclastic sandstones from outcrops in the central part of the Kartli Basin around Tbilisi broadly confirms the main conclusions of studies completed some 30 years ago which were based on the analysis of subsurface samples. However, the surface samples analysed show that zeolitization events typically did not improve, but actually reduced, reservoir quality due to extensive zeolite cementation. The poor reservoir properties of the plug samples, which are age‐equivalent to the proven subsurface Middle Eocene reservoir interval, highlight fracturing as a key factor controlling the presence of exceptional producers (up to 9000 b/d) in the Samgori field complex. The study therefore underlines the critical role of fracturing of the Middle Eocene volcaniclastic reservoir sequence in the Kartli Basin.

Effect of Zeolite to Clay Ratios on the Formation of Zeolite-Clay-White Cement Composite Cylinder as an Encapsulant of Urea Fertilizer

Zeolite-clay-white cement composite cylinders have been prepared for the encapsulant of urea powder. The composites were made by mixing natural zeolite, clay, and white cement at certain ratios using a home-made cylinder mold. All processes were done at room temperature. The composites were characterized using infrared (IR) spectroscopy and X-ray diffraction (XRD). Mechanical properties of the composites were evaluated through compressive strength and water absorption capacity test. The infrared spectra showed functional groups at 3448 and 1636 cm–1, indicating the presence of calcium silicate hydrate as the main product of hydration and pozzolanic reactions in the composite. The XRD patterns also confirmed the presence of calcium silicate hydrate as tobermorite (d = 3.34, 3.22, 2.75, and 2.28 Å) and jennite (d = 4.50 Å). Increasing the natural zeolite ratio in the composite decreased the compressive strength but increased water absorption capacity. The composite cylinders are envisaged as the encapsulant of urea powder and act as a slow-release fertilizer.

Assessment the leaching characteristics and long-term leaching behavior of some radionuclides from synthesized zeolite cement matrix

The development of cementitious materials remains a vital goal to produce valuable products with good mechanical, physical and chemical properties suitable for the safe disposal of concentrated radionuclides resulted from the treatment of contaminated solutions. In this paper, zeolite cement with good properties was laboratory synthesized from industrial by-products fly ash and characterized using various characterization techniques. The leaching characteristics of strontium and cobalt radionuclides from the synthesized zeolite cement were scrutinized conforming with the standard leaching methodology of International Atomic Energy Authority (IAEA). A mechanical strength assessment was executed to characterize the extent of immobilization process of the solidified matrices. The cumulative leaching fraction (ɤ) of the two studied radionuclides was found to be less than 5% in all examined conditions, which implies the applicability of the IAEA-recommended methodology for estimating the diffusion coefficient. The experimental leaching data were regressed nonlinearly to various mathematical kinetic models to assess the controlling leaching mechanism and to determine the leaching parameters. The regression results indicated that strontium (85Sr) and cobalt (60Co) leaching resulted from two succeeding mechanisms: as first order kinetic reaction, and then diffusion. The calculated values of leachability indices signify that the performance of each of the studied matrices is within an acceptable range. A simplified mathematical model, rooted in the first order reaction and diffusion mechanisms, was simulated to predict the radionuclides leaching rates from zeolite cement matrices. By comparing the synthesized zeolite cement with other cementitious materials, it can be concluded that the synthesized material can be classified as an efficient material suitable to immobilize 85Sr and 60Co from radioactive wastes. The acquired findings demonstrated that the studied immobilized waste matrices have acceptable mechanical effectiveness.

Multimineral diagenetic forward modeling for reservoir quality prediction in complex siliciclastic reservoirs

Reservoir quality (RQ) prediction models for sandstones in use by the oil and gas industry primarily emulate mechanical compaction, quartz cementation, and cementation by a few select aluminosilicate minerals during burial. The modeled cements are treated on a kinetic basis using independent Arrhenius-style rate equations, and nonmodeled cements are constrained by empirical observations and data from analog rocks. The nonmodeled cements pose a significant modeling challenge in complex lithic and arkosic sandstones that contain carbonate, clay, or zeolite cements when analog data are not available for constraint. Twenty-nine samples covering a broad range of sandstone compositions were selected from four fields in four different sedimentary basins to investigate the potential of using modern reactive transport models (RTM) to simulate a more comprehensive suite of minerals involved in sandstone diagenesis. A commercially available RTM, GWB® X1t, was configured to model chemical diagenesis in a time–temperature burial framework conceptually similar to that employed in standard industry RQ forward models. Strategies were developed to consistently constrain kinetic parameters, fluid compositions, and fluid fluxes with the goal of standardizing these parameters to reduce configuration and calibration time. Results show that RTM using such standardized parameters can reproduce relative timing and volume changes caused by mineral dissolution and precipitation that are accurate within the uncertainty of the petrographic data constraint. The results suggest that incorporation of RTM into current industry models could provide a valuable improvement to siliciclastic RQ prediction in frontier plays with complex mineralogies wherever calibration data are sparse or unavailable.