Wellbore stability model for horizontal wells in shale formations with multiple planes of weakness

Ding, Yi; Luo, Peng; Liu, Xiangjun; Liang, Lixi

doi:10.1016/j.jngse.2018.01.029

Cited by 46 publications

(22 citation statements)

References 24 publications

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“…S is triangle area made by maximum amplitude and dominant frequency. Based on these data, equation of fitting curve can be established, as shown in Equation 7. M a and M c are maximum amplitude of shale before and after soaking, mV.…”

Section: Establishment Of Hydration Damage Indexmentioning

confidence: 99%

“…1 Clay shale is a common geological formation, which is often encountered in drilling. [5][6][7] These researches found out that rock constitutive relation is variable in hydration evolutionary process. efficiency and causing huge economic losses.…”

Section: Introductionmentioning

confidence: 99%

“…Numerous researches have studied this mechanical influence from hydration damage. [5][6][7] These researches found out that rock constitutive relation is variable in hydration evolutionary process. Correspondingly, damage models of constitutive relation have been established.…”

Section: Introductionmentioning

confidence: 99%

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Hydration index and hydrated constitutive model of clay shale using acoustic frequency spectrum

Liu

Ding

Ranjith

et al. 2019

Energy Science & Engineering

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Clay shale is frequently encountered in drilling. With strong hydration capacity, when clay shale contacts with drilling fluid, rock structural and mechanical property will be affected, causing wellbore instability. Acoustic frequency spectrum is a significant parameter in geophysical logging. The influence of hydration on clay shale can be reflected in acoustic logging. Therefore, in order to identify hydration damage and have precise evaluation for hydration damage, a novel hydration damage index has been built on the basis of acoustic frequency spectrum. Meanwhile, considering the influence of hydration, hydrated constitutive model has been proposed using this new index. Results demonstrate that acoustic frequency spectrum has clear modification due to hydration damage. In the hydration evolutionary process, fracture initiation and propagation happen, decreasing acoustic amplitude and dominant frequency. The whole hydration evolutionary process exhibits S curve with clear three stages. In the initial stage, changing ranges of acoustic amplitude and frequency are small. In the middle stage, clear fracture propagation can be noticed and fracture network is formed, boosting the change of acoustic frequency spectrum. Finally, acoustic frequency spectrum becomes stable, meaning hydration damage has reached its limitation. Hydration damage degree is variable with different conditions, but the tendency still remains typical S curve. Stress‐strain curves simulated from hydrated constitutive model are in good agreement with results of uniaxial compressive test, indicating this model can be used to express shale mechanical property in hydration evolutionary process. Findings of this paper can offer theoretical reference for evaluating hydration damage and are advantageous for drilling operation in clay shale formation.

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Section: Establishment Of Hydration Damage Indexmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydration index and hydrated constitutive model of clay shale using acoustic frequency spectrum

Liu

Ding

Ranjith

et al. 2019

Energy Science & Engineering

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“…Currently, shear failure is built on the basis of Mohr‐Coulomb theory, which can be expressed by classic Mohr's circle . In this paper, since we take account for numerous natural fractures, Mohr's circle with multiple fracture planes can be established using the superposition method, illustrated as Figure .…”

Section: Fracture Initiation In Fractured Reservoirmentioning

confidence: 99%

A novel analytical model of initial fracture pressure for horizontal staged fracturing in fractured reservoir

Liang

Ding

Liu

et al. 2019

Energy Science & Engineering

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The horizontal well-staged fracturing technology has been widely used in many oilfields to enhance well production by creating fracture network. Accurate prediction of fracture initiation is significant for successful hydraulic fracturing operation. However, hydraulic fracture initiation in fractured reservoir is highly tricky due to its rich natural fractures and artificial fractures previously created during staged fracturing. These fractures are thought to be major factors in conducting efficient staged fracturing in fractured reservoir. Therefore, in this paper, induced stress from artificial fractures has been analyzed by using two-dimensional analytical model. Besides, based on the assumption that rock in the formation is composed by rock matrix and fracture plane, considering tensile and shear failure type, failure criterion with multiple natural fracture planes has been developed. By combining impacts from natural fractures and artificial fractures, we establish an analytical model to calculate initial fracture pressure for horizontal staged fracturing in fractured reservoir. These results demonstrate that induced stress is associated with artificial fractures' location, height, and number. This induced stress leads to increment of initial fracture pressure, restricting fracture initiation. Due to natural fractures, there are three types of initiation, which are tensile failure along rock matrix, tensile failure along natural fracture, and shear failure along natural fracture plane. When rock failure is related to natural fracture, initial fracture pressure decreases and is variable with natural fracture plane occurrence. Especially, with large number of natural fractures, only one initiation type exists, which is tensile failure along natural fracture. Additionally, for horizontal borehole, influencing extent of fracture planes is associated with wellbore trajectory. The case study proves the applicability of this analytical model, meaning it can be used to guide horizontal staged fracturing in oilfield. K E Y W O R D Sartificial fracture, fracture initiation, fractured reservoir, natural fractures, staged fracturing

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“…The wellbore instabilities include bit balling, caving, sloughing, stuck pipe, and in severe cases, the collapse of the wellbore may occur. Therefore, the design and selection of drilling fluid play a significant role in minimizing the wellbore instability problems [ 7 , 8 , 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Clay Hydration and Swelling Inhibition Using Quaternary Ammonium Dicationic Surfactant with Phenyl Linker

et al. 2020

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Water-based drilling fluids are extensively used for drilling oil and gas wells. However, water-based muds cause clay swelling, which severely affects the stability of wellbore. Due to two adsorption positions, it is expected that cationic gemini surfactants can reduce the clay swelling. In this work, quaternary ammonium dicationic gemini surfactants containing phenyl linkers and different counterions (Cl− and Br−) were synthesized, and the effect of variation in counterions on swelling and hydration properties of shales was studied. Numerous water-based drilling fluid formulations were prepared with different concentrations of surfactants to study the swelling inhibition capacity of surfactants. The performance of surfactant-containing drilling muds was evaluated by comparing them with base drilling mud, and sodium silicate drilling mud. Various experimental techniques were employed to study drilling mud characteristics such as rheology and filtration. The inhibition properties of drilling mud formulations were determined by linear swelling experiment, capillary suction time test, particle size distribution measurement, wettability measurements, and X-ray Diffraction (XRD). Experimental results showed that surfactant-based formulation containing bromide counterion exhibited superior rheological properties as compared to other investigated formulations. The filtration test showed that the gemini surfactant with chloride counterion had higher filtrate loss compared to all other formulations. The bentonite swelling was significantly reduced with increasing the concentration of dicationic surfactants as inhibitors, and maximum reduction in the linear swelling rate was observed by using a formulation containing surfactant with chloride counterion. The lowest capillary suction timer (CST) was obtained in the formulation containing surfactant with chloride counterion as less CST indicated the enhanced inhibition capacity. The particle size measurement showed that average bentonite particle size increased upon the addition of surfactants depicting the inhibition capacity. The increase in basal spacing obtained from XRD analysis showed the intercalation of gemini surfactants in interlayers of bentonite. The contact angle measurements were performed to study the wettability of the bentonite film surface, and the results showed that hydrophobicity increased by incorporating the surfactants to the drilling fluid.

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Wellbore stability model for horizontal wells in shale formations with multiple planes of weakness

Cited by 46 publications

References 24 publications

Hydration index and hydrated constitutive model of clay shale using acoustic frequency spectrum

Hydration index and hydrated constitutive model of clay shale using acoustic frequency spectrum

A novel analytical model of initial fracture pressure for horizontal staged fracturing in fractured reservoir

Evaluation of Clay Hydration and Swelling Inhibition Using Quaternary Ammonium Dicationic Surfactant with Phenyl Linker

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