Hydraulic fracturing treatment has been proven to be the key factor for shale gas to flow at economic rate. Micro-seismic mapping has shown the extreme complexity of the hydraulic fracture network after the stimulation due to the geological complexity of shale formations. It becomes vitally important to understand the impact of the hydraulic fracture treatment, especially the massive multistage, multi-cluster hydraulic fracturing stimulations, to optimize stimulation and development plans of shale gas reservoirs.
Recent advances in micro-seismic mapping enable realistic modeling of hydraulic fracture network, though with significant uncertainty. Consequently, it is possible, to certain extent, to represent actual large-scale fracture distribution in reservoir modeling and simulation of shale gas development. In this paper, we propose a simulation method that is able to generate highly likely realizations of fracture network based on micro-seismic data, taking into account of data and shale formation uncertainty. The simulated realizations are then used to construct highly constrained unstructured gridding and a connection list of all neighboring cells (SPE 143590), using the Discrete Fracture Modeling (DFM) approach. DFM enables the prediction of production yield curve. With real production data, statistical analysis is done to calibrate and refine the simulation attributes. Based on a well calibrated simulation system, and linking initial hydraulic stimulation, induced fracture network and production data, we predict future stimulated reservoir volume and production yield curve, hence enabling the optimization of stimulation and development.
The proposed approach is extremely computational intensive. Approximations, efficient implementation and parallelization are used to make the approach practical. The approach was tested with success on real field experiments and data and the numerical results have shown great potential of the proposed approach to better understand the impact of hydraulic fracturing treatment.
Shale formations are usually extremely tight with complex pre-existing natural fractures at multiple length scales. Various stimulation technologies, most commonly hydraulic fracturing treatment, are used to create induced fracture network allowing gas flow to production wells at economical rates. The induced fracture networks often have complicated geometry that is difficult to be characterized resulting inaccurate production performance predictions.
The production performance of a shale gas well mainly depends on the induced fracture network and its impacting volume or stimulated reservoir volume (SRV) near the wellbore. Frequent drillings and stimulation treatments are required to maintain global production scale. It is thus vitally important to accurately characterize the induced fracture networks and the resulting stimulated reservoir volumes for optimizing development plan and quantifying reserve estimation uncertainties.
The volumetric water content (θ) of peat soils below the water table is largely controlled by the production of biogenic methane-rich gas bubbles that are subsequently released to the atmosphere, thereby having significant implications for carbon cycling. Geophysical methods have recently shown promise for improving studies of gas storage and release in peatlands. We investigated the relationship between dielectric permittivity and volumetric water content in organic peat soil using ground-penetrating radar. We developed a novel approach for controlling water content using a pressurized test chamber to reduce the volume of bubbles under high pressure as described by the ideal gas law. This method simulates the bubble-rich natural conditions much more closely than previous studies that utilized drying to vary water content. Our results cover a range of highly saturated peat that is commonly observed in poorly decomposed near-surface peat and we demonstrated that a linear model can be used to estimate water content in peat for a range of water contents (i.e. θ>90%). The data collected from samples taken from different peatlands suggests that it is possible to use our resulting model to convert dielectric permittivity extracted from ground-penetrating radar data into free-phase gas concentration via the water content.
Che-Alota, Vukenkeng (Oklahoma State University) | Atekwana, Estella (Oklahoma State University) | Atekwana, Eliot (Oklahoma State University) | Sauck, William A. (Western Michigan University) | Rossbach, Silvia (Western Michigan University) | Werkema, Dale (U.S. EPA, ORD, NERL, ESD, CMB) | Davis, Caroline (University of Missouri Rolla) | Nolan, Jay (Rutgers University) | Slater, Lee (Rutgers University)
New materials with improved mechanical properties and high optical transmission in the full 3-5 μm mid-wave infrared (MWIR) region wavelength are required. Commercially available polycrystalline transparent yttria, with > 100 μm average grain size, does not perform satisfactorily in demanding applications because of its modest strength. One way to improve strength is to develop an ultra-fine grained material with acceptable optical transmission properties. To realize a fine-grained ceramic, one approach is to develop a duplex-phase or composite structure, in which one phase inhibits the growth of the other phase during processing. In this study, mechanical and optical properties of a uniformly fine-grained ceramic composite, comprising a 50:50 vol% mixture of Y2O3 and MgO, are measured and correlated with structure. INTRODUCTION Future IR sensor windows and domes are likely to be subjected to harsher mechanical and thermal environments than those that are used today. Sapphire (Al2O3) is the current material of choice for many window applications, since it is readily available in high optical quality. A comprehensive review of commonly used window materials can be found in the literature (Harris 1993; Savage 1985). Yttrium oxide (Y2O3-yttria) has excellent optical properties in visible, near IR and full 3-5 μm MWIR band and has been used for windows and domes. However, the current processing methods yield materials with >100 μm grain size (Harris, 1993) and inferior mechanical properties relative to that of sapphire. Increased strength can be achieved by reducing the grain size of the final sintered product to submicron range, while maintaining clean grain boundaries (Bamba 2003; Li 1999; Rice 1997). Over the last two decades, nanostructured materials have been the subject of intensive research worldwide, since exceptional mechanical and functional properties can be achieved (Bamba 2003; Li 1999; Rice 1997). Moreover, high-strain-rate superplasticity has been observed (McFadden 1999, Wan 1999) in nanocomposite ceramics, which opens new opportunities for the near-net shape fabrication of such materials.
Britt, Larry Kevin (NSI Technologies, Inc.) | Dunn-Norman, Shari (U. of Missouri Rolla) | Smith, Michael Berry (NSI Technologies, Inc.) | Atekwana, Estella (University of Missouri-Rolla) | Slater, Lee (Rutgers University) | Gupta, Anuj (Lousiana State University) | Numbere, Daopu Thompson (U. of Missouri Rolla) | Fontana, J.V. (Direct Geochemical) | Viellenave, J.H. (Direct Geochemical) | Pelger, J. (J-Environmental, Inc.)
Normally, the objective of hydraulic fracturing is to design and execute a fracture treatment that achieves the desired fracture dimensions (length & conductivity) to maximize a wells production rate and reserve recovery. Treatments are most typically applied in reservoirs with in-situ stresses that yield vertical fractures. Case studies of horizontal fractures and identification of the key parameters unique to horizontal fractures are uncommon, in part due to the fact that oil and gas reservoirs occur in relatively deep subsurface formations.
A research project, sponsored by the U.S. Department of Energy, was undertaken to demonstrate a development method for the significant heavy oil reserves that exist at ultra-shallow depth in the Pennsylvanian sands in Southwestern Missouri and Southeastern Kansas. The principal objective is to demonstrate an economically viable and sustainable method of producing the shallow heavy oil using a combination of microbial enhanced oil recovery (MEOR) treatments and horizontal fracturing in vertical wells. In this application, the purpose of hydraulic fracturing is to expose additional reservoir surface area for subsequent microbial injection. Once the hydrocarbons are contacted by the microbes, the horizontal fractures are to provide a conductive pathway back to the wellbore for the lower viscosity hydrocarbons to flow.
Two wells in the study area, Fauvergue 1 and 5, were cased, perforated, and hydraulically fracture stimulated. Analysis of the treatments with surface tiltmeters confirmed that horizontal fractures were created. Geomechanical studies conducted prior to fracturing confirmed that the Pennsylvanian sands are more competent and have a greater Young's Modulus than previously reported in the literature.
This paper provides documentation of the extensive laboratory study conducted to develop an understanding of the elastic properties of the Warner and Blue Jacket sandstones and shale, fracture fluid sensitivity, and embedment testing.
The paper also reports the horizontal fracture stimulation execution and pressure analysis. Surface tiltmeter data are reviewed with the hydraulic fracturing performance, to determine whether the treatment objectives were achieved.
Heavy oil exists in the shallow Pennsylvanian sands in Southwestern Missouri and Southeastern Kansas. These sands occur over an area of about 8,000 sq. miles that extends for 250 miles along the Kansas-Missouri border as shown in Figure 1. The area reaches a width of roughly 80 miles and covers portions of the Northeast Oklahoma Platform, the Cherokee Basin and the Forest City Basin.1 Heavy oil (ranging from 8o to 25o API) is found in deposits distributed throughout this trend most frequently in rocks of the Cherokee Group of the Middle Pennsylvanian age.2
Chae, Yong S. (Rutgers University)