Browsing by Author "Song, Bo"
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Item Model for Fracturing Fluid Flowback and Characterization of Flowback Mechanisms(2014-08-28) Song, BoA large volume of fracturing fluid that may include slick water and various sorts of additives is injected into shale formations along with proppant to create hydraulic fractures which define a stimulated shale volume a shale gas well will actually drain. While in hydraulic fractures in conventional reservoirs most of the injected fracturing fluid flows back quickly, field observations have reported that load recovery from shale gas wells occurs over a long period, and in some shale formations only a small fraction of total injected fluid is recovered. An unresolved question is whether unrecovered injected fluids are detrimental to well performance. This study emphasizes three main aspects: the location of injected water after fracturing treatment; the mechanisms of water retention underground; and the mechanisms behind the observed flowback behavior. To locate the injected fracturing fluid we cataloged the possible fracture types including the main propped fracture and secondary fractures that may or may not be filled with injected fluid or proppant or even hydraulically connected. The investigation of factors impacting water retention will consider formation properties and fracture configurations of the cataloged locations for injected water and will evaluate the degree to which each factor plays. Finally, we will model long term flowback and formation flow behavior and mechanisms in order to quantify fundamental implications of retained water on well performance and expected ultimate recovery. The significance of this research work lies on understanding how flowback behavior impacts the gas production performance of shale gas wells in both short term and long term view. Whether the unrecovered water blocks the gas flow path to the well or behaves as proppant to keep the fractures open and enhance the conductivity of an induced fracture system should be understood before the fracturing treatment design and flowback scheme determination. More specifically, an aggressive flowback schedule might reduce the effective stimulated shale volume and/or the gas production rate. Therefore, understanding where the injected water is located, how water is distributed underground, how water flows with gas and what controls water flowback are critical to understand the beneficial or detrimental effects of flowback and load recovery on shale gas well production.Item Pressure Transient Analysis and Production Analysis for New Albany Shale Gas Wells(2010-10-12) Song, BoShale gas has become increasingly important to United States energy supply. During recent decades, the mechanisms of shale gas storage and transport were gradually recognized. Gas desorption was also realized and quantitatively described. Models and approaches special for estimating rate decline and recovery of shale gas wells were developed. As the strategy of the horizontal well with multiple transverse fractures (MTFHW) was discovered and its significance to economic shale gas production was understood, rate decline and pressure transient analysis models for this type of well were developed to reveal the well behavior. In this thesis, we considered a ?Triple-porosity/Dual-permeability? model and performed sensitivity studies to understand long term pressure drawdown behavior of MTFHWs. A key observation from this study is that the early linear flow regime before interfracture interference gives a relationship between summed fracture half-length and permeability, from which we can estimate either when the other is known. We studied the impact of gas desorption on the time when the pressure perturbation caused by production from adjacent transference fractures (fracture interference time) and programmed an empirical method to calculate a time shift that can be used to qualify the gas desorption impact on long term production behavior. We focused on the field case Well A in New Albany Shale. We estimated the EUR for 33 wells, including Well A, using an existing analysis approach. We applied a unified BU-RNP method to process the one-year production/pressure transient data and performed PTA to the resulting virtual constant-rate pressure drawdown. Production analysis was performed meanwhile. Diagnosis plots for PTA and RNP analysis revealed that only the early linear flow regime was visible in the data, and permeability was estimated both from a model match and from the relationship between fracture halflength and permeability. Considering gas desorption, the fracture interference will occur only after several centuries. Based on this result, we recommend a well design strategy to increase the gas recovery factor by decreasing the facture spacing. The higher EUR of Well A compared to the vertical wells encourages drilling more MTFHWs in New Albany Shale.