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Collaborating Authors
Abstract Near-surface microseismic recordings from four wells completed in British Columbia, Canada, are analyzed to evaluate completions efficiency and to identify cost savings on future pad completions. Wells were completed using the plug and perforation method in a zipper sequence with slickwater and sand. The wells were monitored utilizing a near-surface array of geophones with an aperture that is twice the depth of the target. Located microseismic events are used to assess the overall success of the completions program in terms of the efficiency of fracture generation, stimulated reservoir volume, propped reservoir volume, stage spacing, well spacing, and well placement. This is accomplished using advanced interpretation methods that include discrete fracture network modeling and propped stimulated reservoir volume estimates. Analysis shows that the presence of a preexisting natural fracture network that is parallel to SHmax enhances fracture growth in this orientation. Fracture lengths mapped with microseismic tend to exceed wellbore spacing by up to 400% unless they intersect local geologic structure, in which case fracture growth perpendicular to the wellbore is truncated. One outcome of creating these long fractures is that most of the created volume will not be propped. Three of the wells exhibited two microseismic event trends per stage and the fourth well generated a single event trend per stage. When two fractures are generated during a single stage, the first fracture tends to locate within the completions interval and the second in the upcoming interval. This creates significant overlap, which has implications for proppant distribution, stage spacing and production. Wells with two trends also generate a greater number of microseismic events early in the treatment, whereas stages with single fracture trends show more consistent event generation over the duration of pumping. Advanced analysis of this microseismic data indicates that changes in stage and wellbore spacing as well as a reduction in fluid volumes or change in fluid type could result in significant completions cost reduction.
Abstract A recent series of tight gas discoveries in the Amin format ion of the greater Fahud area represents some of the most exciting exploration success of this decade in the Sultanate of Oman. The structures have been evaluated as containing very significant amounts of gas locked in a challenging deep and hot environment requiring hydraulic fracture stimulation. Recently, horizontal well trials started taking place in two of the structures aiming for testing efficiency of this type of completion and further evaluation of formation deliverability. Successful completion of horizontal laterals would open new horizons in this challenging environment. Achieving this goal is not possible without thorough evaluation of reservoir conditions followed by completion and stimulation. Horizontal well performance in a tight gas reservoir is largely controlled by the number of hydraulic fractures placed along the lateral and their spacing and conductivity. Designing a reservoir access strategy might not be a trivial task, either, when the well trajectory intersects several productive vertical layers and the reservoir properties are changing laterally. Manual selection of intervals and perforations could be susceptible to mistakes and may be perceived as subjective at times, while also being time and effort consuming. The workflow based on reservoir quality (RQ) and completion quality (CQ) developed in North America for unconventional resources for optimizing completion decisions brings engineering to this process for stage and cluster selection in horizontal sections. This project applies the same reservoir-centric RQ/CQ workflow integrating all available data and creating specific criteria and cutoffs applicable to a specific tight gas field in the Sultanate of Oman.
- North America > United States (1.00)
- Asia > Middle East > Oman (0.93)
- North America > United States > West Virginia > Appalachian Basin > Marcellus Shale Formation (0.99)
- North America > United States > Virginia > Appalachian Basin > Marcellus Shale Formation (0.99)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- (6 more...)
The Numerical Simulation of Hydraulic Fracture Propagation with Competing Perforations at the Defining Plane
Shi, Xian (China University of Petroleum) | Li, Dongjie (China University of Petroleum) | Cheng, Yuanfang (China University of Petroleum) | Han, Zhongying (China University of Petroleum) | Fu, Weiqi (China University of Petroleum)
Abstract Fixed plane perforation technology is regarded as a good mean to address near wellbore tortuosity and reduce breakdown pressure in low permeability reservoirs. To better understand of the fracture behavior in wellbore perforations at the defining plane, a 2D finite element model has been implemented in ABAQUS to investigate the effects of mechanical, perforation and treatment parameters on hydraulic fracture propagation path. The global zero thickness cohesive elements have been inserted into numerical model, thus the existence of natural fractures on patterns of fracture propagation can be considered in this model. It shows that there is a great impact of natural fracture on the fracture propagation path. Moreover, the fracturing fluid viscosity, pumping rate, in-situ stress and perforation parameters also play critical roles on fracture propagation. Comparisons of numerical simulations show that the effects of the stress anisotropy, pumping rate, fluid viscosity, Young's modulus, Poisson's ratio and perforation intersection angle on the hydraulic fracture geometry of exterior fractures and interior fracture at the defining plane are different. It found that the width of interior fracture is almost zero at the near wellbore zone at the end of pumping which induced by the stress interference of neighboring fractures in some cases, thus perforations design at the defining plane must be carefully considered. Additionally, in most cases, hydraulic fractures from exterior perforations tend to propagate upward and downward simultaneously. Although hydraulic fractures initiated from a perforation that misaligned with the direction along the maximum in-situ stress initially at short distance, hydraulic fractures would finally reorient itself to the maximum in-situ stress direction, thus increase chances of creating one simple transverse fracture along maximum in-situ stress orientation. Because the strong stress interference of competing fractures, the possible breakdown of casing and perforation tunnels should be considered before well completion. The simulation results from this study offer some insights to enhance fixed plane perforation design for hydraulic fracturing treatments.
- Asia > China (0.51)
- North America (0.46)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.49)
- Asia > China > Sichuan > Sichuan Basin (0.99)
- Asia > China > Shanxi > Ordos Basin (0.99)
- Asia > China > Shaanxi > Ordos Basin (0.99)
- Asia > China > Gansu > Ordos Basin (0.99)
Abstract In this paper, the authors examine the impacts of natural fractures on the distribution of slurry in a well with a permanent fiber installation and drill bit geomechanics data. Additionally, they propose a framework for further investigation of natural fractures on slurry distribution. As part of the Marcellus Shale Energy and Environmental Laboratory (MSEEL), the operator monitored the drilling of a horizontal Marcellus Formation well with drill bit geomechanics, and subsequent stimulation phase with a DAS/DTS permanent fiber installation. Prior to the completion, the authors used an analytical model to examine the theoretical distribution of slurry between perforation clusters from a geomechanics framework. A perforation placement scheme was then developed to minimize the stress difference between clusters and to segment stages by the intensity of natural fractures while conforming to standard operating procedures for the operator's other completions. The operator initially began completing the well with the geomechanics-informed perforation placement plan while monitoring the treatment distribution with DAS/DTS in real time. The operator observed several anomalous stages with treating pressures high enough to cause operational concerns. The operator, fiber provider, and drill bit geomechanics provider reviewed the anomalous stages’ treatment data, DAS/DTS data, and geomechanics data and developed a working hypothesis. They believed that perforation clusters placed in naturally fractured rock were preferentially taking the treatment slurry. This phenomenon appeared to cause other clusters within the stage to sand-off or become dormant prematurely, resulting in elevated friction pressure. This working hypothesis was used to predict upcoming stages within the well that would be difficult to treat. Another perforation placement plan was developed for the second half of the well to avoid perforating natural fractures as an attempt to mitigate operational issues due to natural fracture dominated distribution. Over the past several years, the industry's growing understanding of geomechanical and well construction variability has created new limited-entry design considerations to optimize completion economics and reduce the variability in cluster slurry volumes. Completion engineers working in naturally fractured fields, such as the Marcellus, should consider the impact the natural fractures have on slurry distribution when optimizing their limited-entry designs and stage plan.
- North America > United States > West Virginia (1.00)
- North America > United States > Virginia (0.90)
- Research Report > Experimental Study (0.68)
- Research Report > New Finding (0.47)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.36)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play (0.36)
- Geophysics > Borehole Geophysics (0.96)
- Geophysics > Seismic Surveying > Passive Seismic Surveying (0.69)
The course presents the fundamentals of hydraulic fracturing, along with addressing the general process, the "terminology," and many of the "real-world" problems - in a concise format. The overall emphasis of the day is how hydraulic fracturing fits-in with, is impacted by, or impacts geologic concerns, reservoir engineering, and operations. The day will provide a general familiarity with fundamentals of the complete hydraulic fracturing process. That is - why it works (or doesn't), where is it applicable, and what might be considered in order to "do better." Introduction – What is fracturing?