Water reservation, especially in remote and drought-prone areas and environmental concerns, are two major drawbacks of water-based fracturing. Waterless fracturing technologies, however, also referred to as green hydraulic fracturing, are friendly to the environment and have the potential to replace water-based fracturing. This article critically reviews such technologies. More attention is given to

Casing collapse is a costly phenomenon in drilling industry that occurred in different geological environment with different geomechanical property. Geomechanical and numerical analysis of casing collapse in Sirri-E, one of the offshore Iranian oilfield in Persian Gulf has been investigated in this work. In this study we tried to model several collapse loading of rock-cement-casing system under real

The carbonate rocks of the Majiagou Formation contain extensive oil and gas resources. To determine the rock type, sedimentary characteristics and sedimentary environment of the Ma51+2 submember, its sedimentary microfacies are distinguished via core observation, thin section analysis, scanning electron microscopy and cathodoluminescence analysis. On the basis of the sedimentary microfacies division

Predicting the PDC bit performance during drilling operation is important for the cost effectiveness of the operation. The majority of PDC bits are assessed based on their performance that are relative to offset wells. Determination of mechanical specific energy (MSE) in real time and compare it with the known MSE for a sharp bit to assess the bit life has been utilized by several operators in the

Majority of the oilfields in the Hongshanzui region are small and complex fault block reservoirs, and the evolution of the sedimentary system under the sequence stratigrapic background has been a controversial topic. Six middle-term base-level cycles were divided, and eight types of lithofacies assemblages were recognized based on the stacking patterns and volumetric partitioning according to the core

Understanding mechanical rock properties is essential for optimal well placement and hydraulic stimulation design which directly impacts hydrocarbon productivity from shale reservoirs with ultra-low permeability. Current industrial practice is to assess spatial variability of subsurface mechanical properties through analyzing core and dipole sonic logs. Seismic inversion is another commonly applicable

Oil transfer in shale formation is different from conventional reservoirs due to the abundant nanopores and organic matters. The various storage states of shale oil make the available models not valid. A model considering fluids desorption and phase behavior, which are the major differences from flow in other types of reservoirs, is important for shale oil reservoir development. Based on experimental

Fracture conductivity is a measure of the fracture ability to transfer fluids from a hydrocarbon-bearing zone to a well. Proppant embedment in soft formations and rock weakening due to the acid/rock reaction limit the stimulation success resulting in sharp fracture conductivity decline. The focus of this study is to increase the rock strength by mineralogical alteration aimed at sustaining long-term

New experimental tests on a suite of tight gas sandstone samples show a strong dependence of both P- and S-wave velocities, Vp and Vs, on hydrostatic confining stress in the range from almost zero to 50 MPa. The Klinkenberg-corrected absolute gas permeability of these samples also exhibited a dramatic stress dependence. It decreased by one to two orders of magnitude as the stress increased. A new approach

Hydrate formation during an offshore oil/gas drilling operation can yield serious problems, such as plugging in the pipeline and damages at the wellhead. On the other hand, the idea of using CO2 hydrate as a self-trapping mechanism has been emerging for sequestering carbon dioxide in the offshore sediments. In this regard, we conducted a fundamental experimental study to investigate the characteristics

A new reservoir quality ternary plot (RQTP) of effective porosity, shale volume, and matrix is presented in this study. We show it to be a useful tool for first-order estimation of the petrophysical zones and reservoir classes of each unit within a reservoir. Subsequently, we combine the RQTP results with permeability and fracturing intensity data in carbonate rocks to provide a better overall characterisation

Prediction of complex diagenesis and the resulting variations in reservoir quality are critical for hydrocarbon exploration. In fact, the limitations of core accessibility and expensive costs of core-based experiments have posed challenges for establishment of diagenetic prediction model. Integrated petrographic and petrophysical analyses are served here to fully understand the dominant diagenetic

Molecular diffusion is the main mechanism of wax deposition, whereas the dispersed water droplets influence the wax diffusivity in water-in-oil (w/o) emulsion by restricting the diffusion path. In the present work, geometric analysis method was used to analyze the blockage effect from dispersed phase on the restricted diffusion path of wax molecules in w/o emulsion, and a correlation was proposed relating

Proppants have evolved from their primary role of preventing fracture closure to performing technically functional roles within reservoirs. This paper presents an extensive review of recent advances in functional proppant technology. Multifunctional proppant roles, such as the enhancement of multiphase flow of reservoir fluids, delivery of CO2 for enhanced gas recovery, detection of fracture geometry

In this work, curves of current dimensionless potential versus recovery factor are computed with models of hydrocarbon production systems. Additionally, a method to estimate production profiles using curves of current dimensionless potential versus recovery factor is presented. The author introduces three definitions, (1) the “production potential” is the maximum rate of hydrocarbon delivery for a

Understanding the features of apertures of hydraulically conductive fractures occurring in the subsurface is vitally important in tight-gas reservoirs. The Cretaceous Bashijiqike Formation in the Kelasu Belt, Tarim Basin, is a gas enrichment reservoir at depths greater than 6,500 m. The matrix permeability is less than 0.1 mD, and generally decreases by one to two orders of magnitude under the reservoir

Thermally induced fractures (TIFs) are common in waterflooded fields where the injection of (relatively) cold water leads to a cooling front that reduces a formation's in-situ stresses. Understanding TIFs is important since their existence impacts oil recovery potential, well injectivity, injection well integrity, and injector-producer well spacing in reservoirs under waterflooding. Identifying and

Nanodiamonds (diamondoids) are the ideal geochemical tool for hydrocarbon-source correlation in high-maturity fields since they are thermally stable and outlast biomarkers (molecular fossils), which deteriorate with thermal maturity. Diamondoids form in the shallow subsurface as organic material reacts with clay minerals in source rock, thereby preserving information about the precursor organic compounds

An intact cement sheath between a liner and its host casing is critical for maintaining well integrity. The liner-casing overlap incorporates a cement sheath and a seal assembly that collectively establish a dual barrier system. This type of barrier provides a unique set of hydraulic and mechanical properties that are necessary to isolate fluids and prevent undesired communication between formations

The southwestern Junggar Basin is an attractive region for oil exploration. A major discovery of high oil production rate from a recently drilled borehole stimulated a new round of extensive petroleum exploration in this region. The potential source beds are within the Permian, Triassic, Jurassic, Cretaceous and Paleogene strata, but no effective oil-prone source rock samples have been drilled so far

As is well known, resin and asphaltene greatly increase the viscosity of the oil, which causes difficulty for heavy oil to flow and to be displaced. Therefore, reducing the viscosity of heavy oil effectively is the key to enhance oil recovery. A hyperbranched copolymer named as HVR grafted with hydrophilic surfactant monomers, was synthesized and evaluated in this paper as an alternative to reduce

Wettability in unconventional reservoirs is poorly understood. However, it plays a fundamental role in fluid-rock interactions, and an understanding of wetting behavior is essential for capillary seal assessments and hydrocarbon reserve estimation and recovery in clay-rich reservoirs. In this study, the wetting behavior of transitional Shanxi-Taiyuan shale from the southern North China basin was examined

The interaction between hydraulic fractures and natural fractures is a key factor in the forming of complex networks during shale fracturing. In spite of abundant natural filling fractures having been found in practical shale layers, previous studies have either ignored the effects of natural fractures or highly simplified them. In order to investigate how the natural filling fracture effect on crack

A transient simulation tool for the gas hydrate slurry flow is crucial for hydrate flow assurance in the petroleum industry. In this work, we propose a new transient model for gas hydrate slurry flow in oil-dominated flowlines. A two-fluid model and a temperature equation are used to describe the gas-slurry two-phase flow. For the modeling of particulate phase flow, number density conservation equation

In this research, molecular dynamics simulation is used to provide a molecular-scale insight into the working mechanisms of the silica nanoparticles in oil detachment from carbonate surface in absence and presence of ionic compounds. The oil model comprises of heptane, decane and toluene mixture. The contents of aqueous phase are variated in different cases: (I) water, (II) water and ions of Na+, Cl−

This study aims to investigate the propagation characteristics of an optimum wormhole to make an efficient acid treatment in carbonate matrix acidizing based on wormhole visualization using micro X-ray computerized tomography (CT) with high resolution. Five cases comprising 25 core-flood experiments under different experimental conditions using Indiana limestone cores were carried out at various injection

This paper demonstrates estimation of in-situ stresses and geomechanical parameters from four-arm caliper logging data for the Duvernay Formation in Western Canada. The four-arm caliper logs also permit identification and classification of borehole sections that display breakouts and sloughing. A poro-visco-elastic Finite Element Method simulator was developed to quantify the time-dependent borehole

Heterogeneity is one of the core content of reservoir characterizations for hydrocarbon exploration and development. However, most heterogeneity studies are conducted based on statistical calculations using permeability and porosity data. Although there have been attempts to evaluate heterogeneity by quantifying the complexity of the logging data, these evaluations rarely consider the spatiotemporal

Non-aqueous drilling fluids are generally favored in risered deepwater drilling operations for their capability to significantly improve drilling performance. However, their use may increase the difficulty of gas kick detection and handling, due to the high solubility of gas at downhole pressure and temperature conditions. A novel managed pressure drilling (MPD) control strategy is proposed here to

Model errors are ubiquitous in practical history matching problems. A common approach in the literature to accounting for model errors is to treat them as random variables following certain presumed distributions. While such a treatment renders algorithmic convenience, its underpinning assumptions are often invalid. In this work, we adopt an alternative approach, and treat model-error characterization

Acid fracturing is an important method to stimulate oil and gas wells in carbonate reservoirs. The main purpose of acid fracturing is to create a high-speed channel for oil and gas flow, and conductivity is an important factor that determines the effect of acid-fracturing construction pressure. Studying the variation trend of the fracture friction coefficient is important to explain the variation in

The identification of lithology while drilling with horizontal well bit is a difficult problem to solve in geosteering. However, due to the existence of “zero length” (the distance between the logging tool and the bit), the lithology at the horizontal well bit cannot be accurately interpreted in real time, which creates a lag in geosteering. Based on logging while drilling (LWD) technology, this paper

The oil reservoirs in the Perm Krai region in Russia are characterized by high formation water salinity (200–230 g/l) and low reservoir temperature (25–30 °C). Currently, about 75% of their remaining reserves have a water cut of more than 50%. Super absorption polymers, also called preformed particle gels (PPGs), have been widely applied to control water production in oilfields; however, no work has

Many reservoirs consist of fully saturated rock masses containing a very complex natural fracture network. In such cases a decrease in the fracture fluid pressure reduces its aperture due to an increase in the effective stresses. In order to tackle the influence of fracture permeability on the pressure field and fluid flow, this paper proposes a Discrete Fracture-Matrix (DFM) model based on the finite

Commercial simulators for the design of oilfield services technologies are required to be fast and robust, hence the numerical implementation of underlying mathematical models is expected to be highly efficient. We present an optimized numerical algorithm based on the multigrid approach for solving the pressure equation in 2D problems of fluid-fluid displacement. This type of problems arise in oilfield

When a well reaches the end of its productive life, it is permanently plugged and abandoned. Even though new technology and verification methods are being evaluated, it is evident that operational, barrier material and qualification challenges together contribute to risk of leaks from abandoned wells or wells to be abandoned in future. Most regulatory authorities constitute zero leak acceptance criteria

Oil seep samples from the Foothill Zone of northern Iraq were geochemically characterized to determine the level of biodegradation and water washing of the seeps and to determine the depositional environment (including sedimentary facies, oxicity, and organic matter type) of correlative source rocks. Eight samples from three seeps sites (Hammam Al-Alil, Qaiyarah, and Fat'ha) were investigated. Detailed

HU is of great importance for the reservoir characterization, which could indicate the fluid behavior and petrography features of the reservoir. During the detailed development of any oil-gas field, the reliable estimation of HU in the reservoir makes an important impact on improving the efficiency of production and predicting the distribution of remaining oil. In this study, a novel method for HU

The efficient development of an oil field mostly depends on a comprehensive optimization of subsurface flow. To account for several discrete or even contradicting objectives, multi-objective optimization (MOO) approach presents multiple optimum solutions for decision-making processes. There are excessive degrees of freedom in any optimization problem of the life-cycle of water-flooding to optimize

Acid etched fracture length and conductivity affect the carbonate stimulation effect. In this paper, acid-etched experiments with large-scale rock plate (1000 mm × 100 mm × 15 mm) were performed to investigate the acid etched fracture length, pattern, and conductivity. The relayed rock plates were etched with spent acid, collected from the outlet of previous plates, to simulate acid flow and reaction

Thermal conductivity is defined as the ability of a material to conduct the heat. Rock thermal conductivity is influenced by several parameters such as mineral composition, geometrical factors, porosity, and saturation condition. Value of the rock thermal conductivity is necessary in all thermal processes in petroleum engineering such as thermal methods of enhanced oil recovery. Laboratory measurement

Asphaltene deposition in the reservoirs, tubbing, and surface facilities causes serious flow assurance problems with significant economic implications. Asphaltene flow assurance challenge results from pressure depletion, fluid compositional change, and electrostatic interactions between the rock-fluid system resulting in deposition inside the reservoir and alteration of petrophysical properties such

Nuclear magnetic resonance (NMR) has emerged as an essential method for appraising gas-shales, quantifying their petrophysical properties, classifying their fluid types, and discerning their productivity. Comprehensive measurement campaigns, as well as reliable thermal-heating experiments, are required to fully understand the NMR mechanism of shale and to further develop future gas-shale exploitation

Waterflood has been widely applied across the world as the most important secondary recovery process to improve reservoir performance. The schemes applied to waterflood projects involve key decision-making which aims to maximize the net present value (NPV) for a given period, improve recovery and sweep efficiency, maintain reservoir pressure, reduce water production, and avoid water recycling. Traditionally

In most cases, oil wells are completed and perforated to produce from multiple reservoirs. Thus, it is crucial to monitor production from each individual reservoir. Therefore, a new prediction method for multi-reservoir production by using temperature logging data is presented in this paper. Firstly, by coupling the wellbore and formation heat transfer with reservoirs heat transfer, a new comprehensive

The research of CO2 erosion-corrosion (E-C) of carbon steel pipelines in wet gas-solid flow, as a critical consideration for oil and gas engineering applications, is increasingly receiving more and more interest and attention. A semi-empirical model for the prediction and risk assessment of the conjoint CO2 E-C rate in such conditions is proposed. The variation of fluid properties with system environment

A kinetic model for the slurry-phase hydrocracking of vacuum residue was proposed under conditions of: 410–450 °C, 0.25–1 hr−1, 160 bar, 1500 Nm3/m3 of H2 to oil ratio, and 500 ppm catalyst (Mo-octoate). A five-lump model with ten reaction pathways was adopted to describe the hydrocracking kinetics, while the hydrotreating reactions were modeled by the power-law approach. The kinetic parameters were

Uncertainty is an important indicator that can provide the confidence in the predictions. However, most machine learning methods in classification problems are incapable of predicting an accurate probability that matches the observed distribution of each class. To overcome this problem and improve the uncertainty analysis in lithofacies classification, a novel calibration process is performed on the

A solution for wet gas metering was developed with a vortex meter by using pressure sensors and correlation technology. For the fluctuating pressure measurement, the micro pressure sensors, especially the probe-transducer systems, were designed to acquire reliable vortex signals. For the experiments, an annular mist flow loop with a film metering system was established, and the tests were conducted

The cross-fracture is one of the basic units of rock fracture network in the deep energy exploitation. The scientific evaluation of the fluid flow behavior of a cross-fracture is a key link in the description of the fluid flow behavior of deep fractured reservoirs. Based on the Weierstrass-Mandelbrot function and combined with 3D printing technology, numbers of cross-fracture models with different

In order to solve the problem of poor acid-resistant of preformed particle gel (PPG) as conformance control material in reservoirs with supercritical CO2 flooding, acrylamide (AM), N,N′-methylene bisacrylamide (MBA) and dimethyldiallylammonium chloride (DMDAAC) were used to prepare an acid-resistant preformed particle gel (AR-PPG) by radical polymerization method. Fourier transform infrared spectroscopy