The KS reservoir is a naturally fractured, deep, tight gas sandstone reservoir under high tectonic stress. Development wells for this reservoir are of depths in excess of 6,500 m TVD. Stimulation is required to provide production rates that sufficiently compensate for the high cost of drilling and completing wells to access this deep reservoir. Hydraulic fracture design and execution must be optimal to ensure economic production. To effectively stimulate a more than 200-m thick sandstone reservoir yielding consistently high performance, it is critical to understand the interaction between hydraulic fractures and natural fractures, as the natural fractures significantly affect the growth and geometry of hydraulic fractures.To this end, a comprehensive study was conducted involving frac pressure analysis of previously stimulated wells, microseismic data analysis, hydraulic fracturing modeling by using a fracturing simulator that honors the natural fracture system, near-wellbore 4D geomechanical simulation of mechanical response of natural fractures during hydraulic fracturing, and large block hydraulic fracturing tests. This study reveals that existing natural fractures results in complexity of hydraulic fracture systems both in the near wellbore region and in the far field region. The complexity in the far field is largely controlled by the intersection angle (defined as the angle between the natural fracture strike and the maximum horizontal stress direction) given the large differential horizontal stress in this field.Based on an understanding of the interaction mechanism, an optimization of the hydraulic fracturing strategy was implemented in KS field. Improvements were made in staging, perforation, diversion, and the pumping schedule, which increased the averaged production rate more than 50% compared with previously stimulated wells.
Introduction: It is believed that strengthening cardiopulmonary function can reduce health risks caused by the COVID-19 virus, and swimming is a practice that could benefit its practitioners during the epidemic context. Objective: Study the effect of swimming on the cardiopulmonary capacity of college students in the context of COVID-19. Methods: A total of 60 volunteers in three groups were trained twice a week for one hour each for 12 weeks. Among them, swimming group A performed freestyle exercises, swimming group B performed breaststroke exercises, and the control group performed reading activities or another study, mainly focusing on staying seated. Results: The cardiopulmonary capacity of groups A and B was improved, while the cardiopulmonary capacity of the control group experienced little change. This shows that swimming training can effectively improve cardiopulmonary capacity in college students. Conclusion: Appropriate swimming training can improve the cardiopulmonary capacity of college students, and optimize their physical fitness, in the context of COVID-19. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.
Reservoirs in the Tarim Basin located in Western China can exceed 6100m [20,000 feet] TVD and often classified as high- pressure high-temperature (HPHT). These sandstone formations are ultra-deep with presence of natural fractures and temperatures approaching 190°C [375°F] and reservoir pressure ranging between 110 to 125 MPa [16,000 to 18,000 psi]. The development of such resources comes with unique challenges that require a coordinated and integrated approach when drilling, collecting sub-surface data, well completions, and intervention operations. All of these tasks pose unique challenges that are often not encountered in other hydrocarbon basins. Hydraulic fracturing is a critical component to the well completion practice and is obligatory in order to maximize well productivity. This type of reservoir poses serious technical challenges that must overcome and account for the geological, geomechanical, and petrophysical interpretation. The integrated approach towards understanding the reservoir combined with the use of a novel fracture diversion technology was undertaken to ensure the maximum surface area contacted by the fracture with the reservoir and wellbore. The hydraulic fracturing design process involved the identification of intervals for multiple perforation clusters across the 200m [650 feet] reservoir section and then executing multiple stage stimulation treatments in which a fluid and proppant schedule would be pumped followed by the application of this dynamic diversion technology. This paper will discuss this case history from a workflow perspective, introduction of this fracturing technology while using a weighted fracturing fluid with a specific gravity of 1.3, the treatment observations identified through real-time microseismic, and discuss how the better reservoir understanding enabled an improved completion strategy. The ten wells with this approach are best in class from a production standpoint when compared to the three tier reservoir potential ranking approach. Finally, the lessons learned from the first phase of this project will help guided future development activities.
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