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Microseismic data and production logs in our study area have confirmed asymmetric developments of the stimulation rock volume in shales with respect to the wellbore, while severe casing deformation problems have been reported frequently in this area. Here, we propose a systematic methodology to investigate the possibility of casing failure due to strong shear stresses induced by asymmetric stimulated zones. A mechanical earth modeling (MEM) is initially performed to determine the in situ stress field in the target layer before fracturing by incorporating the existing geological features, logging data, and rock anisotropy. Then, we provide a computationally cheap and efficient estimation for stimulated rock volume of each stage by considering the possible overlaps in adjacent stages based on the clustered microseismic clouds. Using this approach, a reservoir‐scale 3D coupled model tied to a more detailed near‐wellbore part incorporating the casing string and the cement sheath is established to simulate the development of stimulation zones, stress redistribution, and their impacts on casing deformation as each stage fracturing treatment chronologically goes on. Our numerical results indicate that continuous redistribution and re‐orientation of stress field near the borehole are tracked during pumping the treatment which reveals formation of some pockets of tensile stresses along and around the wellbore. Asymmetric stimulations are observed to generate strong shear stress on the suspended casing. These shear forces result in deflection and S‐shape deformations accompanied with cross‐sectional ovality. Some regions receive repeating treatments, which results in intensifying formation stress heterogeneity and worsen casing deformation severity. The calculation results are compared with measurement of multi‐finger imaging tool (MIT) to validate the accuracy. Our analysis has indicated that simply increasing the flexural strength by increasing thickness of casing cannot radically mitigate casing deformation problems. This paper presents a novel workflow for a coupled modeling of casing deformation during hydraulic fracturing operations, while current modeling efforts assume symmetric bi‐wing fracture geometries. [ABSTRACT FROM AUTHOR]

To attain cement sheath integrity, a tight and ductile microstructure for the cement matrix is desirable. Despite improvements achieved in cement design by employing fiber additives, limitations such as low compressive strength and formation of weak regions may result in fracture initiation points in the cement matrix. In this work we grafted silica nanoparticles on the surface of expandable polymer fibers through a sol-gel process to improve the bonding with the cement matrix and inhibit the formation of weak points in the cement sheath. Considering water-phobic nature of some of these polymeric surfaces, hydrophilic coating of fibers may improve their adhesions to the water-based cement, significantly. The mechanical performance of the samples made of treated fibers are characterized by means of compressive strength, flexural strength, and cyclic loading. Cement samples with nanosilica-treated fibers demonstrated superior results in all mechanical tests in comparison to samples made from untreated fibers. Even at low concentrations, such as 2% by weight, higher flexural strength is observed in the cement with the treated fibers. We also noticed that the flexural strength increases proportionally to the fiber concentration. Therefore, the concentration of additives may be tailored to deter crack propagation in accordance with the other requirements of the cementing operation. The expansive capabilities and rheological properties of the cement are maintained after the surface treatment. The results also demonstrate that the damage to the cement during cyclic loading is reduced when the cement is reinforced with treated fibers that can be interpreted as improved resiliency which is critical in the wells undergone frequent pressure fluctuations during hydraulic fracturing treatments. • Cement resiliency and tensile strength play important role in its integrity. • Fibers of shape memory polymers can be used to improve ductility of cement. • To improve bonding of polymer fibers to the cement matrix, a cost-effective nano-additive is proposed. • Nanosilica coatings improve cement tensile and compressional strengths. [ABSTRACT FROM AUTHOR]