Limestone Samples Research Articles

The effectiveness of some crystallization inhibitors in preventing salt damage to limestone

The present paper studied the effectiveness of some crystallization inhibitors as a preventive method to limestone from salt damage. Amino trimethylene phosphonic acid (ATMP), polyacrylic acid (PA), and citric acid (CA) were evaluated as inhibitors against sodium sulfate and sodium chloride salts crystallizations into limestone (micrite). The modifiers that influenced the transport of Na2SO4 and NaCl solutions inside the limestone samples were evaluated by recording the changes with photography and daily report. USB-Digital microscope, scanning electron microscope SEM coupled with a microanalysis energy dispersive system (EDS), X-ray diffraction (XRD), and weight loss data were used to evaluate the efficiency of these inhibitors. The results revealed that the effectiveness of inhibitors of concentration 0.01 M was better than 0.05 M. 0.01 M polyacrylic acid and 0.05 M amino trimethylene phosphonic acid changed the sodium sulfate crystal habit. Only 0.05 M of polyacrylic transformed halite crystals from cube to octahedron, dodecahedron, and tetrahexahdron. The best inhibitors for salt crystallization and mitigates damages to limestone are polyphosphonate and polyacrylate for sodium sulfate salt and polyacrylic for sodium chloride salt.

Lost circulation mitigation using modified enzyme induced calcite precipitation technique

Circulation loss is a very common and undesirable non-productive time (NPT) event that happens during the oil and gas well drilling operations. Many loss circulation materials (LCM) have been formulated and implemented in the process of gas and oil wells drilling to minimize or mitigate this problem. In-situ calcite precipitation in effective pores can restrict the movement of the water flow between the grains by forming bridges. In this study, different mixes of Enzyme-induced calcite precipitation (EICP) solution are studied and tested in the laboratory to mitigate lost circulation problem. EICP solution is primarily composed of urea, calcium chloride, magnesium chloride, Xanthan Gum, and urease enzyme. Different concentrations and compositions of reagents were tested. The properties of the created precipitates were examined through different techniques such as X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The combination that produced the highest amount of thermally stable calcite with a minimal amount of aragonite, along with the highest precipitation efficiency was further selected for lost circulation application. A solution containing 1M Urea, 0.9M CaCl 2 , 0.1M MgCl 2 , 1 g/L Xanthan Gum, and 3 g/L urease was considered as an optimum combination for an EICP process. Lost circulation experiments were carried out in core flooding experiments on a high permeable Indian Limestone sample at room and elevated temperature conditions with the optimum combination of EICP reagents. The permeability of the samples was measured before and after the treatment. Nuclear Magnetic Resonance (NMR) scan was also run before and after the treatment to determine the pore size redistribution. Results showed that the permeability of the samples was reduced by 99%, NMR results showed that the porosity of the samples was also reduced by 20%. • Investigation of the modified enzyme induced calcite precipitation as a lost circulation technique. • Investigation of incorporating magnesium in an EICP process to precipitate dolomite mineral. • Investigation of incorporating Xanthan Gum as a temperature stabilizer for an EICP reaction. • Coreflooding and NMR experiments with optimized EICP solution as a potential lost circulation material. • 99% reduction in permeability achieved with modified EICP process.

A new model between the Bond and Hardgrove grindability based on volumetric powder filling by using limestones

Grindability measurement as a testing method can be divided into two general categories; the Bond (Gbg) and the Hardgrove grindability index (HGI). Grindability of coal and minerals is influenced by mineralogical parameters, machine parameters and operating parameters. In this study, a Hardgrove mill was used to investigate the grinding behavior of six limestone samples due to the simplicity and the potential usage of the method for the determination of the grindability of limestone on a comparative scale. Up to now, a study determining the effects of the HGI values according to volumetric powder filling still does not exist, especially based on the relation between the HGI and the Gbg. In this study, the six different limestones were tested to determine the effect of powder filling which is one from shortcomings of the Hardgrove grindability. Then, a relationship was establish between the Hardgrove grindability, which was obtained depending on three different volumetric powder fillings, and the standard Bond grindability of limestones. As a result of tests, it was seen that the volumetric powder filling could be important in the grindability in Hardgrove mill that can simulate vertical grinding mills. Additionally, a good relationship was found between the HGI and the Gbg from the presented model, and the validity of the model was proved by a high regression coefficient (R2 = 0.971).

Global survey of limestone used in poultry diets: calcium content, particle size and solubility

Limestone is used in poultry diets as a calcium (Ca) source. Feed formulation is often based on an estimate of limestone Ca content or, less frequently, wet chemistry analysis. However, limestone composition may vary, which has not previously been studied on a large scale. In this study, 641 limestone samples supplied to poultry feed mills in 40 countries across eight global regions were collected and analysed for macro- and micromineral content, particle size (geometric mean diameter, GMD), and in vitro solubility. Mean Ca content of fine limestone (GMD<1000 μm, n=566) was 37.8% (range 33.3-39.7%) and for coarse limestone (GMD>1000 μm, n=75) was 38.0% (range 34.7-40.0%). There was marked variation among and within regions in the concentration of other macro minerals and microminerals. Particle size (GMD) of fine limestone was 288 μm (range 37.7-991.9 μm) and 1,689 mm for coarse limestone (range 301.6-3,067.9 μm). In vitro solubility of fine limestone (5 min incubation, pH=3.0) was 68.4% (range 18.8 to 99.4%). Particle size only explained 52% of the variation in 5 min incubation solubility (R2=0.52). For coarse limestone, mean solubility (30 min incubation) was 65.5% (range 23.2-96%) which was not correlated (R2=0.09) with particle size. Particle size and solubility rate of limestone have been shown to alter Ca and phosphorus utilisation in broilers and laying hens. Hence, better understanding of variation in mineral analysis, particle size and solubility rate would enable more accurate feed inclusion and subsequently digestibility to support health and performance.

THE ROCK COMPRESSIBILITY CHARACTERISTICS OF SOME INDONESIAN RESERVOIR LIMESTONES

Rock compressibility is an important formation rock properties. It infl uences various processesin reservoir and rock formations that encompass from sources of reservoir driving energy, changes inother reservoir properties, to land subsidence. Various studies have been performed and published, butno comprehensive studies have ever been performed on Indonesian reservoir rocks. This article presentsresults of such studies on Indonesian limestones, reservoir rocks that have contributed much to Indonesia’snational oil and gas production for decades. The study was carried out in order to study the characteristics oflimestone in its relation to rock porosity. A set of 84 limestone samples taken from fi ve productive formationsin Indonesia is used in the study. Some existing and widely known mathematical correlations/models are alsoused to assist the study. Some of the results show that the existing models are not always valid for some ofthe rocks, and therefore a new model is proposed for medium-hard and vuggy limestones. The results alsoshow that limestone characteristics are not related to rock types and place of origin, but instead to rockhardness and degree of vuggy pore presence.

Seismic Wave Propagation in Partially Saturated Rocks With a Fractal Distribution of Fluid‐Patch Size

AbstractLaboratory experiments on partially saturated rocks show that seismic attenuation can be significant. The main mechanism, wave‐induced local fluid flow (WILFF), is affected by the spatial fluid distribution, especially in conditions of patchy saturation at different spatial scales. We propose a theory to obtain the seismic properties of partially saturated rocks based on fractal (self‐similar) patches, leading to an effective frequency‐dependent fluid modulus. The model combines the differential effective medium and Biot‐Rayleigh theories, where the patches are inclusions incrementally added, such that the effective fluid calculated in the current addition serves as host fluid in the next one. The analysis shows that adding identical inclusions in one or several steps produces nearly the same results, but the seismic properties depend on the scale range (radius) of the inclusions, fractal dimension Df of the self‐similar distribution, parameter of the exponential distribution, mean radius r0 and variance of the Gaussian distribution. Forced‐oscillation experiments were performed on a limestone sample under partial water‐saturation conditions at seismic frequencies (2–500 Hz), to obtain the velocity dispersion and extensional attenuation. The proposed theory provided a reasonable description of these experimental data as well as other published measurements on tight carbonate and Berea sandstone.

On the mechanical anisotropy of argillaceous Cobourg limestone: fabric tensor approach

The mechanical response of Cobourg limestone is anisotropic, which stems from heterogeneity of its fabric. In this work, a new fabric-dependent approach is developed for the description of strength and deformation characteristics of this rock. The quantification of fabric is carried out by employing the basic principles of stereology and the specific fabric descriptor used is the so-called mean intercept length. The results demonstrate that the material may be perceived as transversely isotropic and the mechanical response is affected by the volume fraction of argillaceous partings. The latter are spatially variable, so that the notion of Representative Elementary Volume (REV) is not, in general, applicable. A numerical study is included involving simulation of triaxial tests conducted on differently oriented samples of Cobourg limestone.

Experimental investigation on permeability, meso-damage and fractal characteristics of limestone caprock under THM coupling based on μCT technology

Limestone caprock permeability and damage characteristics have a significant impact on the tightness and stability of salt cavern gas storage. To investigate the gas sealing capacity of limestone as caprock for a gas reservoir at different burial depths, triaxial compression coupled with permeability tests of limestone subjected to different confining pressures and temperatures were carried out using the improved MTS 815 test machine. After the tests, X-ray micro-computed tomography (μCT) is used to perform CT scanning of the limestone sample after seepage failure to estimate the rock meso-damage. The experimental results depicted that: (1) At the confining pressures of 10 MPa, 20 MPa and 30 MPa, the final permeability increases with the increase of temperature, while at the confining pressures of 40 MPa, the evolution of the final permeability is opposite. (2) The pore radius of limestone is concentrated in the range of 0–200 μm, and the pore with a radius greater than 1200 μm is the main permeability channel with the greatest contribution. The final permeability is positively correlated with porosity. (3) The fractal dimension decreases with the increase of confining pressure, and some areas of rock do not have fractal characteristics when the confining pressure reaches 40 MPa. Permeability after rock damage is positively correlated with the fractal dimension and the maximum pore diameter and negatively correlated with the tortuous fractal dimension, according to the fractal permeability model. These experimental results and analyses provide scholars and engineers with a thorough understanding of cap rock tightness in the construction of deep-earth gas storage reservoirs.

Investigating the effects of specimen diameter on the relationships between mechanical and physical properties of limestone

Engineering applications, either on or within rock bodies, typically require detailed characterizations of rock physical and mechanical properties, as both properties affect the design process and construction phase and are also related to safety and sustainability of structures. Various in-situ and laboratory tests have been used to quantify rock properties. However, the tests are expensive, time consuming and require high quality test samples, especially for laboratory tests. Additionally, available core samples may not meet test standards, which require about 54 mm (NX size) core, as suggested by the American Society for Testing and Materials (ASTM) and the International Society of Rock Mechanics (ISRM). This study aims to investigate the effects of core sample diameter on the relationships between mechanical and physical properties of rock, using the example of limestone as a test material. 190 limestone core samples were prepared in five different diameters: 24.94, 38.07, 47.7, 53.99 (NX) and 63.16 mm. Uniaxial compressive strength (UCS), diametrical and axial point load index (PLID-A), indirect tensile strength (ITS), Schmidt hammer (SHV), natural unit weight (γn), specific gravity (Gs), water content (wc) and porosity (n) tests were performed on these core samples. The results indicate that sample diameter clearly affects the relationships between mechanical and physical properties of limestone rock, leading to broad measurement variations for most tests. Substantial agreement was found between this study and previous studies of NX size samples of limestone.

Analysis of Chemical Compositions of Portland Cement and Limestone from Four Geopolitical Zones of Nigeria

Cement, a major binding material in concrete making, influences the quality of concrete so produced with it; as such its chemistry dictates the chemistry of the concrete. Poor quality cement has recently been implicated as the main causes of incessant building collapses in Nigeria. The physicochemical analysis of limestone used in the production of various brands of Portland cement in four geopolitical zones of Nigeria (north east NE, north west NW, north central NC, and south west SW) was investigated using standard methods. Each of the limestone and cement samples was randomly collected from their respective sample points at the four different geopolitical zones of Nigeria. Each of the collected samples was ground and sieved to 2 mm mesh size. The limestone was rich in lime content that ranged from 45.91% ± 0.30% to 49.0% ± 0.19%. Among the cement samples, percent SiO2 ranged from 19.95 ± 0.25 (NW) to 20.18 ± 1.02 (NC), Al2O3 4.98 ± 0.18 (NW) to 5.82 ± 0.38 (NE), Fe2O3 2.76 ± 1.00 (NE) to 3.82 ± 0.21 (SW), CaO 60.18 ± 0.27 (NE) to 65.10 ± 0.98 (NC), MgO 1.93 ± 0.04 (NC) to 2.50 ± 0.10 (NE), SO3 0.93 ± 0.50 (NE) to 2.02 ± 0.13 (NW). The results showed that virtually all the cement samples analyzed conformed well to the BSEN 196-2 standard. However, the loss on ignition (LOI) deviated considerably (7.82% to 8.72%) from 4% maximum by the standard. Also, the lime saturation factor (99.70%) obtained for north central cement was slightly higher than the specified range of 92.0 to 98.0%. It could be deduced from this study that the various cements available in Nigerian market from the four geopolitical zones are of good quality. Nevertheless, other processes that lead to the production of a good concrete such as the mix ratio of cement, gravel, sand and water, use and quality of iron rods, and other building materials need to be professionally checked for quality assurance. The findings from this study can be a useful guide to the chemist, environmentalist, construction industry, and the general public on the quality of cements available in Nigerian market.

Geochemical and petrographic approach for the origin of the limestone blocks of thewalls of the Great Temple of Hattusha, Çorum (N-Turkey)

The socle stones of the Great Temple in the Lower City of the Hittite capital city, Hattusha (Çorum Province) have been studied for the first time by petrographic and geochemical analysis (Sr isotope, stable isotope, and trace element geochemistry). Study objectives were to determine the carbonate facies of the stone samples used in the Great Temple and investigate their possible sources. Petrographic analysis of 10 limestone samples presents five clusters of different microfacies. Stable isotope (δ13C and δ18O) analysis displayed the presence of 5 groups in parallel with petrographic analysis. Trace element analysis of the same groups displayed considerable difference among the stone samples and 87Sr/86Sr isotope ratios change between 0.70697 and 0.706867. Based on the results, it can be stated that the building using stones are from probably five different sources. This is of great importance to better understand the construction process and the acquisition of the building materials.

Anchoring Multi‐Scale Models to Micron‐Scale Imaging of Multiphase Flow in Rocks

AbstractImage‐based pore‐scale modeling is an important method to study multiphase flow in permeable rocks. However, in many rocks, the pore size distribution is so wide that it cannot be resolved in a single pore‐space image, typically acquired using micro‐computed tomography (micro‐CT). Recent multi‐scale models therefore incorporate sub‐voxel porosity maps, created by differential micro‐CT imaging of a contrast fluid in the pores. These maps delineate different microporous flow zones in the model, which must be assigned petrophysical properties as input. The uncertainty on the pore scale physics in these models is therefore heightened by uncertainties on the representation of unresolved pores, also called sub‐rock typing. Here, we address this by validating a multi‐scale pore network model using a drainage experiment imaged with differential micro‐CT on an Estaillades limestone sample. We find that porosity map‐based sub‐rock typing was unable to match the micrometer‐scale experimental fluid distributions. To investigate why, we introduce a novel baseline sub‐rock typing method, based on a 3D map of the experimental capillary pressure function. By incorporating this data, we successfully remove most of the sub‐rock typing uncertainty from the model, obtaining a close fit to the experimental fluid distributions. Comparison between the two methods shows that in this sample, the porosity map is poorly correlated to the multiphase flow behavior of microporosity. The method introduced in this paper can help to constrain the sources of uncertainties in multi‐scale models in reference cases, facilitating the development of simulations in complex reservoir rocks important for for example, geological storage of CO2.

A low-diversity, silicified Hirnantia Fauna from Butuo, southwestern Sichuan, on the western margin of Yangtze Platform

The latest Ordovician Hirnantia Fauna is distributed worldwide including South China, but with very few records from the western margin of the Yangtze Platform. A silicified Hirnantia Fauna from the uppermost Tiezufeike Formation in the Laoga section, Butuo County, southwestern Sichuan, enriches the fauna’s record and warrants the recognition of the upper part of the Tiezufeike Formation as the Kuanyinchiao Bed. Etching bulk limestone samples from this level with acetic acid yielded 275 specimens of Dalmanella testudinaria, Plectothyrella crassicosta, and Hindella crassa. The population dynamics are analyzed for three successive populations in the section. Size-frequency histograms and survivorship curves indicate gradual improvement of the palaeoenvironments during the end of the Late Ordovician glaciation. The low-diversity brachiopod assemblages recognized in our study are assigned to the Dalmanella-Plectothyrella Community (DP Community) according to their dominant species. It is comparable with two other examples of DP communities, one from the neighboring Guizhou Province of Southwest China, and the other from the Baltica Region.

Optimization of the acetic acid method for microfossil extraction from lithified carbonate rocks: Examples from the Jurassic and Miocene limestones of Saudi Arabia

An optimization experiment with different acid concentrations was carried out to assess the use of acid to minimum sustainable limits for the extraction of microfossils from indurated limestones. Two different limestone formations of Jurassic and Miocene ages were tested. Different concentrations of acid ranging from 50 to 100% and processing times varying from 2 to 10 h were tested for optimal recoveries. The acid residue recoveries show a similar trend for both formations. The weight percentage of residue with particle size >1 mm decreased as the acid concentration increased, especially in the 50–80% acid concentration range. On the other hand, the weight percentage of the smallest size particles > 0.063 mm increased as acid concentration increased. This means that the higher concentrations of acid dissolve more of the unnecessary large particles while the foraminifera, which comprise the sand fraction size, are left in the residue. Although higher acid concentrations with longer reaction times yielded better recoveries than with less reaction time, we recommended a 60% concentration of acetic acid and a reaction time of 10 h for optimal recovery of micropaleontological samples in Saudi Arabian carbonate rocks. By lowering the recommended concentration, the consumption of acid is reduced without compromising the recovery of microfossils.•Acetic acid leaching method is applied on two different age limestone samples to extract foraminifera.•Different concentrations of acetic acid are tried and tested, and consensus is made on an optimum concentration of 60% for a submersion time of 10 h.•The sample recoveries are optimal while using this concentration for a time of 10 h.

Geochemical and petrographic approach for the origin of the limestone blocks of thewalls of the Great Temple of Hattusha, Çorum (N-Turkey)

The socle stones of the Great Temple in the Lower City of the Hittite capital city, Hattusha (Çorum Province) have been studied for the first time by petrographic and geochemical analysis (Sr isotope, stable isotope, and trace element geochemistry). Study objectives were to determine the carbonate facies of the stone samples used in the Great Temple and investigate their possible sources. Petrographic analysis of 10 limestone samples presents five clusters of different microfacies. Stable isotope (δ13C and δ18O) analysis displayed the presence of 5 groups in parallel with petrographic analysis. Trace element analysis of the same groups displayed considerable difference among the stone samples and 87Sr/86Sr isotope ratios change between 0.70697 and 0.706867. Based on the results, it can be stated that the building using stones are from probably five different sources. This is of great importance to better understand the construction process and the acquisition of the building materials.

Diagenesis Study of Jatiluhur Formation at Cipamingkis River, Bogor Regency, West Java, Indonesia

Diagenesis studies in the Jatiluhur Formation are still relatively new, especially in the Cipamingkis River. This research can provide information in the form of components and characteristics of sandstone in the Jatiluhur Formation which can be used as a basis for further research or useful information in the oil and gas industry. Knowledge of diagenetic could be one of the factors that affect in raservoir quality, espesially in sandstone. In this study, data collection was carried out through surface mapping, which is 55 rock samples were obtained from stratigraphic measuring section with a path length of ±2 Km in the Cipamingkis River. The data is in the form of information on sedimentarry structure, textures and composition. There were 23 sandstone and 2 limestone samples which were then subjected to petrographic analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results of study are several features of diagenesis were found including compaction that works in the form of point contact, long contact, concavo-convex contact and suture contact and dominated by mechanical compaction, while in limestone there is a brittle fracture feature in bioclasts. The cement found in the form of calcite cement, quartz and clay minerals that the form of kaolinite, smectite and illite, while the limestone is in the form of blocky and fibrous to bleded which is filled with calcite minerals. Dissolution occurs in the minerals of quartz, feldspar, and mica. The mineral replacement that is commonly found occurs in quartz and feldspar minerals. In limestone, there is an intergranular micritization. The dominant type of porosity found was interparticle with an average of 10.4% found between 3 – 23%. The history of diagenesis that occurs in rocks in the Jatiluhur Formation begins with the initial deposition of eogenesis, followed by burial mesogenesis and ends with telogenesis which reveals rocks on the surface.

Geological appraisal of the Theban cliff overhanging the Hatshepsut temple at Deir el-Bahari

Throughout its existence the Temple of Hatshepsut, as well as two other royal sanctuaries, the temples of Mentuhotep II and Thutmose III, located in the great bay of Deir el-Bahari, have been under constant threat of falling rocks from the overhanging Theban cliff. The PCMA UW archaeological expedition at Deir el-Bahari, which has progressed with the study and conservation of the Hatshepsut temple since the 1960s, has implemented a project designed to address the issue of the protection of the temple from damages that could be caused by environmental processes (rainwater and seismic activity) affecting the Theban cliff behind the monument. In a geological survey of the fractured limestone cliff, the evidence from 31 observation stations was appraised and samples of Esna Shale and Theban Limestone were examined in order to ascertain the degree of the cliff’s instability and fragility. The results were used to prepare a 2D model presenting the environmental processes threatening the ancient substance.

Effects of ultrasonic waves on water imbibition into oil-wet carbonate reservoirs (a case study)

In this study, imbibition tests with and without ultrasonic radiation were performed on limestone samples obtained from the Asmari formation, which is the main Iranian oil reservoirs. The test results have shown a significant increase in the oil recovery with ultrasonic radiation. Reducing the interfacial tension (IFT) and thus reducing the capillary holding force of oil is considered a possible mechanism for increasing oil recovery from oil-wet rock. The capillary pressure curve shows that a relatively large increase in the oil recovery from oil-wet samples will occur if the IFT decreases and the gravity force becomes a dominant force.

Assessment of Avroman Limestone Formation for Portland Cement Industry, Halabja Area, Kurdistan Region, NE-Iraq

Limestone is the main constituent of the raw materials used in manufacturing cement. In this study, the limestone deposits from the Avroman Formation are evaluated by using chemically and mineralogical techniques for their suitability to be used as a raw material for the cement industry. Twenty-one samples of limestone are collected from different beds of the Avroman Formation for petrographic study which shows that the limestone samples consist mainly of crystalline calcite. Physical and mechanical tests are performed in addition to the mineralogical and geochemical analysis using x-ray diffraction (XRD), x-ray fluorescence (XRF). Geological review and obtained results show that there is a good potential for industrial-grade limestone. The major clay minerals in the clay samples are chlorite, illite, montmorillonite, were as kaolinite appears as minor clay minerals. The geochemical analysis indicates that the limestone of Avroman formation has a wide range of CaO (46.13-56.00), Al2O3 (0.01-0.86), SiO2 (0.00-1.51), Fe2O3 (0.00-1.25), MgO (0.24-0.71), K2O, Na2O, TiO2, and MnO are traces. The physical properties (water absorption and moisture content) and chemical-mineralogical composition of the formation reflect that the dry process is preferable for the production of Portland cement. Mechanical analyses, especially compressive strength show that the quarrying and crushing will be competitive economically during manufacturing. From the results of the analyses, we conclude that the limestone of the formation and clay material of the study area are of good quality and fulfill the international standards of Portland cement.

The Effects of Calcination on Mineral Composition and Physical Properties of Limestones and Oyster Shells Derived from Different Sources

Limestones and oyster shells are normally used in raw or roasted meal form in the livestock diet. Calcination is intended to improve the mineral concentration and physical characteristics of limestones and oyster shells which vary based on different chemical compositions, textures, and impurities of their types and habitats. The present research aimed to study the effects of calcination on mineral composition and the physical properties of limestones and oyster derived from various sources. Limestone samples from three local limestone mining and oyster shell samples from three shellfish species were calcined by burning at a temperature of 800-1000°C. The calcined products were analyzed for mineral content (Ca, P, Mg, Cu, Zn, and Mn), physical properties (bulk density, tapped density, specific density, and angle of repose), and particle size. Results indicated that calcination had no significant effect on Ca and P concentrations but reduced micro mineral concentration. Limestones had a higher Mg concentration than that of oyster shells, and calcination increased Mg concentration. Calcined oyster shells had higher densities, percentages of fine particles, and lower angles of response. The results suggested that the type of limestones and oyster shells could determine their thermal decomposition properties.