Numerical investigation for different casing deformation reasons in Weiyuan-Changning shale gas field during multistage hydraulic fracturing

https://rgu-repository.worktribe.com/preview/244954/MOHAMMED%202019%20Casing%20structural.pdf

Casing structural integrity and failure modes in a range of well types: a review.

Casing deformation from fracture slip in hydraulic fracturing

Numerical simulation of casing deformation during volume fracturing of horizontal shale gas wells

\n This paper presents a case study of fault reactivation and induced seismicity during multistage hydraulic fracturing in Sichuan Basin, China. The field microseismicity data delineate a fault activated near the toe of the horizontal well. The spatio-temporal characteristics of the microseismicity indicate that the seismic activity on the fault during the first three stages is directly related to the fluid injection, while after Stage 3, the seismic activity is possibly due to the relaxation of the fault. The fault-related events have larger magnitudes and different frequency-magnitude characteristics compared to the fracturing-related events. Three-dimensional (3D) fully coupled distinct element geomechanical modeling for the first two hydraulic fracturing stages and a shut-in stage between them is performed. The modeling result generates features of microseismicity similar to that of the field data. The energy budget analysis indicates that the aseismic deformation consumes a major part of the energy. The simulated fault shear displacement is also consistent with the casing deformation measured in the field. The model is also used to investigate the impact of possible operational changes on expected seismic responses. The results show that lower injection rate and lower fluid viscosity would be helpful in reducing casing deformation but not in mitigating seismicity. Decreasing the total fluid injection volume is an effective way to mitigate the seismicity, but it may hinder the stimulation of the reservoir formation and the production of the well.

Fault reactivation and induced seismicity during multistage hydraulic fracturing: Microseismic analysis and geomechanical modeling

Investigation of casing deformation during hydraulic fracturing in high geo-stress shale gas play

Intelligent, comprehensive analytical model and optimization method for well type/ trajectory and pad deployment during cluster drilling

Reservoir shale has the characteristics of bedding planes, strong anisotropy, and strong imbibition ability under ultralow water saturation, which has an important impact on wellbore stability of horizontal wells. Therefore, the physical and chemical properties of reservoir shale were analyzed, and a mechanics model of wellbore stability was established considering the elasticity and strength anisotropy. The wellbore stability was analyzed considering the anisotropy parameters of formation elasticity and strength and imbibition conditions. The results show that the anisotropy of elasticity and strength under the condition of imbibition are important parameters for evaluating the stability of reservoir shale borehole. Considering the interaction between fluid and reservoir shale, the weakening of the strength of the bedding structure is the reason for wellbore instability of reservoir shale. Bedding planes and microfractures provide rapid imbibition channel, and the imbibition volume increases, which further causes fracture expansion and strength weakening, and then leads to wellbore instability. Multistage effective plugging of bedding, microcracks and macroholes during drilling is the key to maintain the stability of shale wellbore.

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Analysis of Wellbore Stability considering the Interaction between Fluid and Shale


 The Triassic Baikouquan Formation reservoir in the Mahu Sag, Junggar Basin is characterized by tight sandy conglomerate oil reservoir with long drilling cycle and great fracturing difficulty. The factory drilling and fracturing techniques of horizontal wells for the Ma131 Well Block of Mahu Oilfield have been determined by regional geological characteristics research and optimization scheme design.
 The key technologies for horizontal well drilling speed improvement were explored by designing small three-stage wellbore structure, customizing the PDC bit properly, optimizing drilling tool combination, and selecting the drilling fluid with inhibition and plugging ability. The factory reservoir stimulation technique carried out horizontal well hydraulic fracturing with small well spacing for two sets of beds, and adopted bridge plug + clustering perforation staged fracturing and slick water + gel composite fracturing technology.
 12 wells in a drilling pad were arranged in the demonstration area with the depth of 5000m, the distance between adjacent sections was 150m or 100m, with the horizontal section length of 1800m. Batching drilling operation pattern was adopted, with 3⁃well drilling for each of rig. Rapid inclining prevention drilling through vertical sections adopted PDC bit + screw + MWD, with high rotary speed and high flow rate. In the build-up section, radical drilling parameters was used to improve the top drive rotary speed and release the torque. In the horizontal sections, rotary steering tool + low speed high torque screw was adopted. The application of this technology achieved good results, with average drilling cycle of 48.3 d and average ROP of horizontal section increased by 77%. The fracturing construction adopted high pad fluid ratio, high sand ratio and high pump rate. More than 10,000 m3 fluid was injected in a single well with high-intensity proppant injection. The factory operation was carried out in the order of construction from the two sides to the middle well with microseismic monitoring. Factory fracturing with small well spacing generated stress interference and improved the fracture reconstruction effect. Higher shut-in pressure, more microseismic events and large-scale stimulated reservoir volume had been carried out in horizontal wells fractured later.
 The factory drilling and fracturing techniques of horizontal wells for the Ma131 Well Block have achieved the goals of improving drilling speed and volume fracturing, which provided technical support for the efficient development of the tight sandy conglomerate oil reservoir of the Mahu Oilfield.

Lingzhan Zou

Papers

Investigation of casing deformation during hydraulic fracturing in high geo-stress shale gas play

Intelligent, comprehensive analytical model and optimization method for well type/ trajectory and pad deployment during cluster drilling

Analysis of Wellbore Stability considering the Interaction between Fluid and Shale

Factory Drilling and Fracturing Technology for Tight Sandy Conglomerate Oil Reservoir in the Junggar Basin