Ceramic Proppants Research Articles

Effect of surface wettability of ceramic proppant on oil flow performance in hydraulic fractures

AbstractCeramic proppants are critical products for holding induced fractures open and enhancing hydrogen productivity in low‐permeability reservoirs. Though the effects of proppant size and proppant type on the well productivity have been well studied in the past, the role of the proppant surface wettability in the oil flow performance has not been thoroughly investigated. To help the readers and the industries understand the wetting behavior of ceramic proppants, this research was designed to analyze the effect of the proppant wettability on the flow efficiencies of oil and water under different conditions (for example, various proppant size, water saturation, and waterflooding). Also, it was required to determine the optimal wettability of proppants in the available candidates for the enhancement of oil recovery in the hydraulic fracturing process. Results of the work indicate that the proppant wettability plays an essential role in the productivities of water and oil in tight sandstones. Compared with the same‐size oil‐wet proppants, the mixed‐wet proppants contribute to increasing the oil flow efficiency and reducing the produced volume of water. However, an increased value of proppant size can significantly enhance the oil recovery. Besides, using the oil‐wet proppants, the waterflooding phenomenon can lead to a lower oil recovery than that of the non‐water‐flooded specimen. Based on the findings of the microscopic structural characteristics of the proppant surface, a fluid channel mechanism was proposed to help understand the proppant wettability effect on the flow behaviors of oil and water. This research can provide guidance on the determination of proppants in the designs of hydraulic fracturing operations. These findings can help the reservoir engineers dealing with hydraulic fracturing better design the surface wettability of the proppants, especially for those reservoirs with a multi‐phase flow.

Ceramic Proppants Based on Ultrabasic Rocks of Kazakhstan Chromite Ore Deposits

The purpose of the work is the obtaining of magnesium silicate ceramic proppants, based on ultrabasic overburden rocks of Kempirsai deposits of chromite ores (Kazakhstan). The chemical and mineralogical composition of ultrabasic overburden rock was studied by chemical, microscopic and X-ray diffraction analyzes. It is established that the main mineral of ultrabasic overburden rocks is serpentine, present in the form of fibrous chrysotile and lamellar antigorite. In the impurities are iron oxides and hydroxides, chrome spinel, carbonates, quartz. Assessment of the use of overburden rocks as a raw material for the production of ceramic proppants was carried out. The sintering interval of overburden rocks was determined at 1280-1300 °C. The sintering firing optimum temperature of ceramics, based on this type of raw material is 1300 °C. It is established that to harden the structure of magnesium silicate ceramic it is necessary to activate the raw material thermally at a temperature of 1000 °C. The influence of binder type on the properties of magnesium silicate proppants, based on the Kempirsai serpentinites was studied. Magnesium silicate proppants, based on ultrabasic overburden rocks, were obtained with the following properties: apparent density – 1.6 g/cm3, strength resistance (52 MPa) – 14%, sphericity and roundness – 0.8; chemical resistance (hydrochloric acid) – 98%, static strength of the fraction 16/20 - 72–118 N/granule. The field of application is oil and gas production, metallurgy and ceramic industries.

Nanoparticles Patterned Ceramsites Showing Super-Hydrophobicity and Low Crushing Rate: The Promising Proppant for Gas and Oil Well Fracturing.

An ideal proppant showing super-hydrophobicity and enough strength to bear high closure stress is revolutionary for the effective exploration of gas or oil in shale. Here, the ideal proppants were obtained by wrapping specially treated phenol formaldehyde resins around the cover of the traditional ceramsites. The resin coating is patterned with innumerable fluorine-modified silica nanoparticles, whose thickness is controllable. Benefitting from the low surface energy of fluorine, nano-roughness structures from nano-silica, and the adhesive action of the resin, the modified proppant exhibits awesome properties. The nanoparticle-patterned resin gives the ceramic proppants a water contact angle of 157.8° that has been proved to be stable after being treated in strong acid, thus dramatically accelerating the fracture conductivity for oil by 150% whereas totally preventing water passing through. Besides, it is the resin that reduces the crushing rate of the proppants by 52% and decreases the density of the proppants to 1.63 g/cm³.

Toughening effect of mullite whisker within low-density ceramic proppants

Main crystal phases of low-density ceramic proppants prepared by bauxite and feldspar are granular corundum and whisker-shaped mullite. Mullite whiskers are interlocked with one another and piled up inside the pores. High aspect ratio of mullite whiskers inside the pores can greatly enhance the fracture toughness. The dominant toughening mechanism for the proppants is attributed to crack bifurcation and deflection and pulling out and bridging effect of mullite whiskers.

粉煤灰基经济型陶粒支撑剂的制备与改性研究

粉煤灰基经济型陶粒支撑剂的制备与改性研究

Effect of wettability of ceramic proppant surface in guar gum solution on the oil flow efficiency in fractures

Abstract Guar gum and its derivatives have been the most commonly used polymers to increase the viscosity of fracture fluids. Ceramic proppants are vital products for enhancing oil and gas well productivity in low-permeability reservoirs. In the last several decades, abundant studies have been found in the investigation of proppant size, shape, compositions on the fracture conductivity. However, few types of research can be found to study the proppant wettability effect on the oil and gas flow efficiency. In our research, eight experiments were conducted using traditional guar gum fracturing fluid. Results of this work indicated that ceramic proppant promotes oil flow efficiency from sandstone core samples to proppant packs and thus should promote oil well productivity. The mechanism behind this phenomenon is believed to be the formation of oil flow channels across the fracture face due to the imbibition of oil in the core onto the oil-wet surface of the proppant, promoting oil flow from the core to the fracture. After guar gum was added the results inverted, this phenomenon for water-wet proppant is believed to be increased by the viscosity of fracture fluids which increased the viscosity of water, promoting oil flow from the core to the fracture. Nevertheless, the stimulation effect of oil-wet proppant on oil flow efficiency can be reduced by the presence of guar gum solution. Inside the proppant matrix filled with guar gum fracturing fluid, oil can be blocked inside the proppant matrix as a discontinuous phase while the aqueous phase can be easily mixed with the guar gum fluid and then be transferred out.

Preparation and characterization of mullite whisker reinforced ceramics made from coal fly ash

Ceramics with mullite whiskers were prepared from coal fly ash and Al2O3 raw materials, with AlF3 used as an additive. The phase structures and microstructures of the ceramics were identified via X-ray diffraction and scanning electron microscopy, respectively. The results show that pickling of coal fly ash is an effective method for enhancing the flexural strength of ceramics. Sintering temperature and AlF3 addition were also key factors influencing the creation of ideal ceramics. The ceramic made from pickled coal fly ash, 6 wt% AlF3, and sintered at 1200 °C, exhibited the highest flexural strength of 59.1 MPa, and had a bulk density of 1.32 g/cm3 and porosity of 26.8%. The results show that ceramic materials made under these conditions are ideal candidates for manufacturing ceramic proppants for the exploitation of unconventional oil and gas resources.

Frac Sand Supply & Demand Australia

Natural gas is an essential commodity for modern Australia. It’s needed for power generation and is an indispensable feedstock for manufactured products such as fertilizers, plastics & chemicals. The distinction between “unconventional” gas & “conventional” gas is simply based on the type of rock the gas is found in. Both “conventional” & “unconventional” natural gas is methane. CSG & Shale gas is almost pure methane whereas conventional gas may also contain ethane, propane, butane, and other hydrocarbons. Gas demand in eastern Australia continues & will increasingly need to be supplied from unconventional sources such as coal seam & tight shale gas formations which generally need the use of hydraulic fracturing techniques to allow the economic extraction of gas. Frac sand competes with ceramic proppants which are all imported. Frac sand must meet the tight specifications outlined by API RP-56. Key factors include: crush resistance, sphericity / roundness, acid solubility & sizing. The demand will rise as more production holes are commenced to stimulate gas production in the years ahead. Only ~ 4% of coal seam gas holes in the Surat Basin have needed frac sand in recent years but this is expected to rise to 40% within 3 year. The frac sand grade used is primarily 20/40# with smaller quantities of 16/30#, 40/70# & 70/100# making up the balance. There are few producers of frac sand in Australia. Logistics is a key component of the delivered price. There is a trend towards the end users preferring delivery in pneumatic tankers.

Thermal behavior of samarium oxide – Ball clay mixtures for high macroscopic neutron capture cross section ceramic materials

The effect of the addition of samarium oxide (Sm2O3) in the thermal behavior of (66%) kaolinitic ball clay was studied and compared with the pure clay.The incorporation of Sm2O3 is of technological interest for the design of smart traceable ceramic proppants used for unconventional gas and oil well stimulation. These high macroscopic neutron capture cross section proppants are used to obtain relevant information, such as the location and height of the created hydraulic fractures, through a neutron based detection technology.The study comprised a set of thermal analysis up to 1400 °C and the sintering behavior of the clay, up to 5% of addition. The developed texture and microstructure was also assessed. A simple mechanical characterization was performed as well.No important effects in kaolinite dehydration temperature (500–600 °C); and mullites formation (primary and secondary) were observed (990 and ≈1200 °C). The sintering range of the studied clay is 1080–1360 °C; the 5% wt. addition resulted in 80 °C decrease of the final sintering temperature, due to the more active flux nature of the added oxide.Mixtures fired at 1250 and 1400 °C resulted in dense ceramic materials with mullite as principal crystalline phase accompanied by quartz and cristobalite; imbibed in a viscous glassy phase which was proportionally increased by the added oxide. The mullite content and cell parameters were not affected. No samarium containing binary or ternary crystalline phases were detected, inferring that the rare earth is dissolved by the active viscous glassy phase thermally formed from the clay crystalline phases. No significant effect was observed in the spherical diametral compression test.Low concentration addition of the oxide did not affect the porosity or water absorption of the developed ceramics. Only the 5% wt. addition resulted in a noticeably higher de-sinterization with the appearance of macro-porosity if fired at 1400 °C.

Algorithms for 3D Particles Characterization Using X-Ray Microtomography in Proppant Crush Test

We present image processing algorithms for a new technique of ceramic proppant crush resistance characterization. To obtain the images of the proppant material before and after the test we used X-ray microtomography. We propose a watershed-based unsupervised algorithm for segmentation of proppant particles, as well as a set of parameters for the characterization of 3D particle size, shape, and porosity. An effective approach based on central geometric moments is described. The approach is used for calculation of particles’ form factor, compactness, equivalent ellipsoid axes lengths, and lengths of projections to these axes. Obtained grain size distribution and crush resistance fit the results of conventional test measured by sieves. However, our technique has a remarkable advantage over traditional laboratory method since it allows to trace the destruction at the level of individual particles and their fragments; it grants to analyze morphological features of fines. We also provide an example describing how the approach can be used for verification of statistical hypotheses about the correlation between particles’ parameters and their crushing under load.

OPTIMISATION OF HYDRAULIC FRACTURING DESIGN IN LOWER OLIGOCENE RESERVOIR, KINH NGU TRANG OILFIELD

Kinh Ngu Trang oilfield is of the block 09-2/09 offshore Vietnam, which is located in the Cuu Long basin, the distance from that field to Port of Vung Tau is around 140 km and it is about 14 km from the north of Rang Dong oilfield of the block 15.2, and around 50 km from the east of White Tiger in the block 09.1. That block accounts for total area of 992 km2 with the average water depth of around 50 m to 70 m. The characteristic of Oligocene E reservoir is tight oil in sandstone, very complicated with complex structure. Therefore, the big challenges in this reservoir are the low permeability and the low porosity of around 0.2 md to less than 1 md and 1% to less than 13%, respectively, leading to very low fracture conductivity among the fractures. Through the Minifrac test for reservoir with reservoir depth from 3,501 mMD to 3,525 mMD, the total leak-off coefficient and fracture closure pressure were determined as 0.005 ft/min0.5 and 9,100 psi, respectively. To create new fracture dimensions, hydraulic fracturing stimulation has been used to stimulate this reservoir, including proppant selection and fluid selection, pump power requirement. In this article, the authors present optimisation of hydraulic fracturing design using unified fracture design, the results show that optimum fracture dimensions include fracture half-length, fracture width and fracture height of 216 m, 0.34 inches and 31 m, respectively when using proppant mass of 150,000 lbs of 20/40 ISP Carbolite Ceramic proppant.

Sintering mechanism of high-intensity and low-density ceramic proppants prepared by recycling of waste ceramic sands

ABSTRACTWaste ceramic sands were effectively used to prepare the high-intensity and low-density ceramic proppants, realising the recycling of the waste ceramic sands. The technology involved the pelletising in an intensive mixer, in which the waste ceramic sands and other starting materials were added, and followed by heat-treatment under different sintering conditions. The sintering temperature, holding time and heating rate were optimised by investigating the crystalline phase, microstructure, density and breakage ratio of the obtained proppants. The results showed that the proppants sintered at 1260°C for 2 h with a heating rate of 5°C min–1 under air atmosphere exhibited high crush resistance and low density, with the breakage ratio of 8.5% under 52 MPa closure pressure and bulk density of 1.65 g cm–3. The proppants prepared by bauxite, waste ceramic sands and sintering aids are promising candidates as high-intensity and low-density fracturing proppants in future applications.

Determination of loamy resources impact on granulation of ceramic proppants and their properties

Currently, the global oil & gas sector is focused on enhanced natural gas exploration from unconventional rock formations. The potential deposits are located within large-scale basins of impermeable shales (hydrocarbons accumulated in closed pores) with plastic zones at great depths with high reservoir pressure. These severe geological conditions determine the application of granulated propping agents, named “proppants”. They are pumped with hydraulic fluid during hydraulic fracturing and subsequently locate tightly inside created rock fractures. Proppants function as a prop to facilitate gas flow up the wellbore. Quartz sands are applied mainly for low pressure basins. However, only ceramic proppants, granules produced from raw clays in a mechanical granulation and sintering process, are proper for deeper shales due to their homogeneity, higher sphericity, and mechanical and chemical stability.Aim of this research was verification of the impact of natural loamy resources (aluminosilicates in powder form) mixed with binder on ceramic proppants quality. Utility of the clays was estimated by their particle size distribution (PSD by laser diffraction method) and thermal stability (thermogravimetry - TGA). The unique platy morphology was determined by scanning electron microscopy (SEM), while energy dispersive spectroscopy (EDS), X-ray fluorescence (XRF) and X-ray diffraction (XRD) revealed chemical-phase composition. Moreover, aluminosilicates were subjected to analysis of specific surface area (BET method) – very crucial for powder consolidation into granules in mechanical granulation.Quality of the granulated, and consequently sintered, bodies was evaluated by calculations of roundness and sphericity coefficient, specific gravity and bulk density, combined with microtomography (μCT) - a key investigation of porosity and proppant settlement in fracture. SEM studies also revealed phase transitions due to high temperature exposition of the green proppants and the correlation with proppant strength, evaluated in crush tests. Moreover, measurements of turbidity and solubility in acids revealed risk of the granules' decay in the shale gas wells.The obtained outcomes show dependence of the proppant's structure on the binder and the loamy materials ratio, proving the utility of the applied natural resources in the granules production. In consequence, these proppants can be used for hydraulic fracturing in severe mining conditions in accordance to the strict international ISO standards.

Preparation of a Ceramic Proppants for Hydraulic Fracturing Using F – Type Fly Ash

Preparation of a Ceramic Proppants for Hydraulic Fracturing Using F – Type Fly Ash

Crushing characteristics of four different proppants and implications for fracture conductivity

Proppants are widely used during hydraulic fracturing in the oil and gas industry. This paper compares the crushing characteristics of four different types of proppant with three different size ranges that are widely used for hydraulic fracturing in North America. The proppant properties were evaluated using data obtained from a modified crush test. The grain shape before the test, the grain breakage pattern, the stress-strain response of the proppant pack, and the change in particle-size distribution caused by compressive stresses of up to 40 MPa were measured. At the higher compressive stresses, significant differences were observed between the various proppant types as well as for different size ranges for a given proppant type. The results show that the constrained moduli of resin-coated sand and ceramic proppant are 30% higher than those for Jordan sand and Genoa sand. Genoa sand exhibits more grain crushing than Jordan sand, while resin-coated sand and ceramic proppant experienced only minor fracturing at compressive stresses of 40 MPa. The grain shape and size distribution measurements were used to empirically estimate and compare the permeability and fracture conductivity for different proppant packs. Mesh 20/40 and 30/50 ceramic proppants, and mesh 20/40 resin-coated sand are predicted to have twice the permeability of the other proppants at 40 MPa. A good agreement was found between the estimated permeability and published laboratory results for fracture conductivity. This indicates that careful characterization of the particles obtained from a crush test can provide a fast and reliable approach for evaluating proppant pack permeability and fracture conductivity as well as changes in these properties under different compressive stresses without the need to conduct elaborate conductivity tests. Empirical equations quantifying permeability change for four types of proppant with three different sizes are derived with the effect of proppant embedment on fracture conductivity considered. These equations can be incorporated into hydrocarbon production simulations to select proppant types and sizes.

Development of Sodium Hydroxide-Activated Metakaolin with Nanocarbon Materials as Synthetic Ceramic Proppants

The use of proppants in hydraulic fracturing has significantly grown worldwide in recent years. Discoveries of large unconventional reservoirs in the north of Brazil have collaborated to give it the 10th position among countries with the world's largest shale reserves. Nowadays, studies on nanomaterials that are used as additives in proppants are the focus of North America's companies and universities in order to develop either proppants that can suffer mechanical and chemical changes inside the reservoir or that enable their traceability and direction. This paper presents a study on synthesis and characterization of metakaolin’s based ceramic proppants incorporating different types of nanocarbon materials. The method adopted was based on use of high intensive mixing of raw material (metakaolin) granulated with alkaline water solution of dispersed carbon nanomaterials. The SEM analysis testify the carbon nanomaterials dispersion on proppant bulk structure. Mechanical tests (crush resistance or K-value) indicated that metakaolin based proppants reached similar characteristics of white sand natural proppants.

Effect of raw material milling on ceramic proppants properties

Abstract Low density and high breakage resistance ceramic proppants were developed from kaolin, bauxite and monoaluminum phosphate (MAP). The effect of the particle size on the raw materials over the density, the open porosity and the breakage resistance of the proppants was evaluated. The phase composition and the structure of the proppants due to the milling process were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and pore size distribution by mercury intrusion. The proppants obtained with raw materials of smaller size improved its breakage resistance and developed a smaller open pore size, achieving an apparent density of 2.4 g/cm3 with a breakage ratio of 9.61% under 64 MPa. Some properties of the AG3 proppants with sand, low density ceramic proppants of the literature and commercial low density ceramics proppants were compared.

After Drop in Activity, Haynesville Shale Sees Resurgence

What was once old is now new again in US natural gas production. Once a crown jewel of shale in the US, the Haynesville has seen a resurgence in activity after a steady drop. Now, as natural gas consumption increases and the oil price remains low, companies are taking advantage of a potentially valuable opportunity in the area. Located in east Texas and northern Louisiana (Fig. 1) the Haynesville was the largest US producer of shale gas. In November 2011, it averaged a record high production of 10.4 Bcf/D—but as natural gas prices decreased in the years leading to the oil price downturn, other plays in the Appalachian region of the US such as the Marcellus and the Utica began to surpass it in production. By 2015, shale gas production in relatively liquids-rich areas such as the Eagle Ford and the Permian were also producing more than the Haynesville. The demise of the Haynesville appeared to be short-lived, though. In the past 18 months, the US Energy Information Administration (EIA) noted significant increases in drilling activity and well production rates, which have raised overall natural gas production in the region. Natural gas production reached 6.9 Bcf/D in September after remaining near 6.0 Bcf/D on average for the past 3 years. Beyond the Numbers Fig. 2 highlights some of the trends in the Haynesville. The EIA projected natural gas production to increase by 146 MMcf/D from October to November 2017. Rig count has nearly doubled from 2015 to the end of 2017. A drop in well costs has helped drive the surge in activity. In 2014, the Haynesville had the most expensive costs in the US primarily because of the challenges its fuel-bearing rocks presented. The formations were among the deepest in the country, with some as deep as 15,000 ft. In the Appalachian region, wells are in areas where formations range from 2,000- to 12,000-ft depth. The shale formation thickness in the Haynesville is slightly narrower than other US shale plays as well, ranging from 100 to 350 ft. In addition, the high pressure and temperature conditions led to stimulation treatments consisting of high-strength proppant and more thermally stable fluids. These fluids consisted of large polymer loadings of guar and sometimes derivatized guar gelling agents. Higher-quality resin-coated and ceramic prop-pants were commonly pumped as the primary proppant, increasing costs and forcing companies to adopt a strategy of “quality over quantity” in terms of production volumes (SPE 187315).

Alumosilicate ceramic proppants based on natural refractory raw materials

The sintering-strengthening effect of the additions of the highly ferrous bauxite (with Fe2O3 content of 20-25 % in the calcined state) in the compositions with refractory clays was established. It was found that in the temperature range 1350-1500°C the additions of bauxite in amounts of 10-40% have a fluxing effect due to the iron oxide introduced with bauxite in compositions with clay. An increasing the bauxite additive in the amount of 50-70% ensures its strengthening effect by increasing the total content of the mullite of the prismatic habit in the firing products of composites with clay. Preliminary clay and bauxite calcination at 900 °C and an increase in the content of bauxite additive up to 50-70% in compositions with clay allow to produce aluminosilicate proppants with a bulk density of 1.62-1.65 g/cm3 and compressive strength up to 52 MPa.

Microstructure and fracture mechanism of low density ceramic proppants

Solid wastes coal gangue and magnesium slag were added to prepare low density ceramic proppants at sintering temperatures below 1300 °C. The addition of solid wastes greatly decreases sintering temperature and preparation cost. The morphology and phase composition of the proppants were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the main crystal phases of the proppants are granular corundum and rod-like mullite, and the proppants have better sphericity. Furthermore, the most suitable sintering temperature is 1250 °C, and the resulting ceramics exhibit transgranular fracture. This means that rod-like mullite crystals provide strong toughening and reinforcing effects.