Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Results
Abstract Ability to induce complex, highly connected fracture networks, that can remain open during production, is the key to unlock permeability challenged shale gas plays. Within the time and pressure scale of hydraulic fracturing operations, it is difficult to create fracture complexity in ductile shales. However, when subjected to a high rate/pulse loading, rock might exhibit a brittle to ductile transition and a complex fracture network might be created. Along these lines, the concept of pulsed fracturing, that customizes the pressure-time behavior of a pulse source to create multiple fractures, is introduced. In this paper, an integrated 3D model that quantifies fracture initiation, growth, and coalescence due to initial and post-peak pulse loading is presented. The simulation involves a numerical algorithm that couples tensile/shear/compactive failure algorithms with dynamic fracture propagation and pore fluid pressure. Geomechanical modeling approach makes it possible to optimize pulsed fracturing for different shale plays. After constitutive model description and presentation of key aspects of the model, the model is employed to a reservoir dataset to evaluate pulsed fracturing as an alternative fracturing technique. The results show that, if designed accurately, pulsed fracturing could help trigger a ductile to brittle transition and can generate complex fracture networks.
- North America > United States > Texas (0.46)
- North America > United States > Colorado (0.28)
- North America > United States > West Virginia (0.28)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.93)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play (0.68)
Abstract Robust and reliable hydraulic fracturing models that appropriately account for random initiation of fractures, strongly nonlinear coupling among deformation, fracturing and fluid flow in fracture apertures and leakage into porous rock matrix, would be a key step toward developing a better understanding of physics associated with hydraulic fracturing process. In this paper, we present a physics-based hydraulic fracturing simulator based on coupling a quasi-static discrete element model (DEM) for deformation and fracturing with conjugate lattice network flow model for fluid flow in both fractures and porous matrix. The coupled DEM-network flow model reproduces a variety of realistic growth patterns of hydraulic fractures. The effects of in situ stress, fluid viscosity, heterogeneity of rock mechanical properties and injection rate on the fracture patterns will be presented and discussed. In particular, simulation results of multistage horizontal wellbore with multiple perforations clearly demonstrate that elastic interactions among multiple propagating fractures, strong coupling between fluid pressure fluctuations within fractures and fracturing, and lower length scale heterogeneities, collectively lead to complicating fracturing patterns.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.51)
Abstract Shale gas has become an increasingly important source of natural gas (CH4) in the United States over the last decade. Due to its unconventional characteristics, injecting carbondioxide (CO2) to enhance shale gas recovery (ESGR) is a potentially feasible method to increase gas-yield while both affording a sink for CO2 and in reducing the potential for induced seismicity. This study examines CO2 -ESGR to better understand its feasibility and effectiveness. We explore the roles of important coupled phenomena activated during gas substitution especially vigorous feedbacks between sorptive behavior and permeability evolution. Permeability and porosity evolution models developed for sorptive fractured coal are adapted to the component characteristics of gas shales. These adapted models are used to probe the optimization of CO2 -ESGR for injection of CO2 at overpressures of 0MPa, 4MPa and 8MPa to investigate magnitudes of elevated CH4 production, CO2 storage rate and capacity, and of CO2 early-breakthrough and permeability evolution in the reservoir. For the injection pressures selected, CH4 production was enhanced by 2.3%, 14.3%, 28.5%, respectively, over the case where CO2 is not injected. Distinctly different evolutions are noted for permeability in both fractures and matrix due to different dominating mechanisms. Fracture permeability increased by ~ ? for the injection scenarios due to the dominant influence of CH4 de-sorption over CO2 sorption. CO2 sequestration capacity was only of the order of 10 m when supercritical for a net recovery of CO2 of 10 m.
- North America > United States > Texas > Fort Worth Basin > Barnett Shale Formation (0.99)
- North America > United States > Oklahoma > Anadarko Basin > Alabama Field (0.91)
Upfront Predictions of Hydraulic Fracturing and Gas Production in underexplored shale gas basins: Example of the Posidonia Shale Formation in the Netherlands
TerHeege, J.H. (TNO Petroleum Geosciences) | Zijp, M. (TNO Petroleum Geosciences) | DeBruin, G. (TNO Petroleum Geosciences) | Buijze, L. (TNO Petroleum Geosciences)
Abstract Upfront predictions of hydraulic fracturing and gas production of potential shale gas targets in Europe are important as often large potential resources are deduced without detailed knowledge on the potential for successful stimulation. Such predictions are challenging as they need to be based on limited available data, i.e. without well tests or proper case studies. In this study, a geological model was constructed for a representative area in the South of the Netherlands (Noord-Brabant province) where a potential shale gas target (the Posidonia Shale Formation) is present in the subsurface. Petrophysical analysis of rock properties and geomechanical analysis of the stress field are performed. The sensitivity of hydraulic fracturing to rock properties, stress state and treatment schedules was studied using a commercially available hydraulic fracturing simulator. A systematic series of simulations was performed for a range of input parameters to address geological uncertainty and optimum stimulation treatment. The results show that uncertainty in leakoff coefficient and minimum horizontal stress are most important in predicting fracture dimensions and conductivity. Minor upward growth of fractures is observed for all scenarios. Analysis of Coulomb stress changes due to hydraulic fracturing shows that opening of fractures alone is unlikely to cause fault reactivation.
- North America > United States (1.00)
- Europe > Netherlands (1.00)
- Europe > Norway > Norwegian Sea (0.25)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geophysics > Seismic Surveying (1.00)
- Geophysics > Borehole Geophysics (1.00)
- 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 > Pennsylvania > Appalachian Basin > Marcellus Shale Formation (0.99)
- (4 more...)
Abstract Some rocks, such as shales, are highly anisotropic in their mechanical behavior. In such rocks, the value of the maximum principal stress that causes shear failure depends not only on the confining stress, but also on the angle ร between the maximum principal stress and the normal vector to the bedding plane. Triaxial compression experiments were carried out on two types of organic-rich mudstones at different bedding angles ร and confining pressures s3. Two triaxial compression datasets from experiments and 10 datasets from the literature were fit to the Pariseau and the Jaeger plane-of-weakness (JPW) models. Results show that Pariseauโs model is more accurate for 10 of the 12 anisotropic rocks, whereas the JPW model is more accurate for the other two rocks, which were both rocks that had a low degree of strength anisotropy. Post-test examination of computerized tomography (CT) and thin-section images shows that for highly laminated organic-rich shales, there is a transition regime of angles ร lying between angles of about 10ยฐร<35ยฐ, wherein the failure surface follows an irregular path that may jump between the weak plane and intact rock. In this regime, the strength of the rock is lower than the strength predicted by the JPW model.
- North America > United States > Texas (0.97)
- South America > Argentina > Neuquรฉn Province > Neuquรฉn (0.31)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- South America > Argentina > Patagonia > Neuquรฉn > Neuquen Basin > Vaca Muerta Shale Formation (0.99)
- North America > United States > Texas > East Texas Salt Basin > Cotton Valley Group Formation > Bossier Shale Formation (0.99)
- North America > United States > Louisiana > East Texas Salt Basin > Cotton Valley Group Formation > Bossier Shale Formation (0.99)
- North America > United States > Arkansas > East Texas Salt Basin > Cotton Valley Group Formation (0.99)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (0.97)
Abstract Hydraulic fracturing technique has been widely applied in the enhanced geothermal systems, to increase injection rates for geologic sequestration of CO2, and most importantly for the stimulations of oil and gas reservoirs, especially the unconventional shale reservoirs. One of the key points for the success of hydraulic fracturing operations is to accurately estimate the redistribution of pore pressure and stresses around the induced fracture and predict the reactivations of pre-existing faults. The fracture extension as well as pore pressure and stress regime around it are affected by: poro- and thermoelastic phenomena as well as by fracture opening under the combined action of applied pressure and in-situ stress. A couple of numerical studies have been done for the on this for the purpose of analyzing the potential for fault reactivation resulting from pressurization of the hydraulic fracture. In this work, a comprehensive analytical model is constructed to estimate the stress and pore pressure distribution around an injection induced fracture from a single well in an infinite reservoir. The model allows the leak-off distribution in the formation to be three-dimensional with the pressure transient moving ellipsoidcally outward into the reservoir with respect to the fracture surface. The pore pressure and the stress changes in three dimensions at any point around the fracture caused by thermo- and poroelasticity and fracture compression are investigated. Then, the problem of constant water injection into a hydraulic fracture in Barnett shale is presented. In particular, with Mohr-Coulomb failure criterion, we calculate the fault reactivation potential around the fracture. This study is of interest in interpretation of micro-seismicity in hydraulic fracturing and in assessing permeability variation around a stimulation zone, as well as in estimation of the fracture spacing during hydraulic fracturing operations.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.58)
- Energy > Oil & Gas > Upstream (1.00)
- Energy > Renewable > Geothermal > Geothermal Resource (0.34)
Abstract Tri-axial hydraulic fracturing experiments using supercritical Co2 (SC- Co2), water and viscous oil have been conducted in order to investigate how the viscosity of fracturing fluid affects fracture propagation and fracture mode. We performed these experiments on cubic granite specimens and monitored acoustic emission (AE) with 16 sensors. AE data analysis allows us to clarify fracture propagation and its mode. The effects of fluid viscosity on the distribution of AE sources and the fracture mode are discussed. Macroscopic observations of the surface fractures were consistent with located AE sources. The distribution of AE sources indicated that fracturing with low viscosity fluid such as SC- Co2 can induce more widely and complexly extending fractures than those with higher viscosity fluid like water and oil. In addition, the analysis of the fracture mechanism showed that low viscosity fluid such as SC- Co2 induces shear dominant fracture, while high viscosity fluid induces tensile dominant fracture. Thus, since Co2 has a higher affinity to shale than methane and enhances methane desorption, Co2 fracturing could be an effective technique particularly for shale gas recovery.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Igneous Rock > Granite (0.62)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.47)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Storage Reservoir Engineering > CO2 capture and sequestration (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)
Abstract The Marcellus Shale is one of the main U.S. shale plays with more than 140 trillion cubic feet (Tcf) of recoverable gas/condensate (E.I.A) in Pennsylvania and West Virginia. Using the appropriate completion and stimulation designs for reservoirs in a given location is crucial to increase the productivity of the play. Understanding rock properties and reservoir characteristics in gas condensate area and their behaviors during the well stimulation is necessary in order to optimize treatment design. This case study aims at optimizing well and completion design parameters such as well spacing, lateral length, azimuth or hydraulic fracturing properties and improving well productivity. An integrated reservoir study involving geomechanics, fracture design and production analysis was carried out, coupled to a multivariable statistical analysis. The purpose of this paper is to apply multivariable statistical analysis in conjunction with production analysis to understand the relationships between rock properties and hydraulic fracturing efficiency within the reservoir. Fifty percent of the Marcellus Shale is composed of clay in the area of interest and typically, clay shales are anisotropic in strength and deformability. The brittle failure characteristics vary from east to west of the play which can affect the proppant transport and ultimately the well productivity. The investigation is based on both proprietary and public information data for the Marcellus formation (around the area of interest in Marshal County, West Virginia). Production proxies, such as maximum gas and condensate rate in the first 12 producing months were selected and merged with well completion and stimulation data. Final data sets were then subjected to a multivariable statistical analysis and a commercial Geographic Information Systems (GIS) application was used to understand geographical performance variation within the play. Fracture modeling and Rate Transient Analysis (RTA) were applied to this study to identify flow regimes and obtain determine some hydraulic fracture and reservoir properties. At last, the relationships between well performances, completion design and reservoir behavior were better understood.
- North America > United States > West Virginia (1.00)
- North America > United States > Virginia (1.00)
- North America > United States > Pennsylvania (1.00)
- (3 more...)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play > Shale Gas Play (0.83)
- 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 > Pennsylvania > Appalachian Basin > Marcellus Shale Formation > Marcellus Shale Well (0.99)
- (3 more...)
- Well Drilling > Drilling Operations > Directional drilling (1.00)
- Well Completion > Hydraulic Fracturing > Fracturing materials (fluids, proppant) (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Well performance, inflow performance (1.00)
- Information Technology > Data Science (0.47)
- Information Technology > Information Management (0.34)