Abstract
Tight oil is a kind of unconventional oil and gas resource with great development potential. Due to the unconventional characteristics of low porosity and low permeability in tight oil reservoirs, single wells generally have no natural productivity, and industrial development is usually conducted in combination with horizontal wells and hydraulic fracturing techniques. To capture the flow behavior affected by fractures with complex geometry and interaction, we adopted embedded discrete fracture models (EDFMs) to simulate the development of fractured reservoirs. Compared with the traditional discrete fracture models (DFMs), the embedded discrete fracture models (EDFMs) can not only accurately represent the fracture geometry but also do not generate a large number of refine grids around fractures and intersections of fractures, which shows the high computational efficiency. To be more consistent with the real characteristic of the reservoir and reflect the advantage of EDFMs on modeling complex fractures, in this work, the hydraulic fractures are set as oval shape, and we adopted 3-dimensional oil–gas two-phase model considering capillary forces and gravity effects. We developed an EDFM simulator, which is verified by using the fine grid method (FGM). Finally, we simulated and studied the development of tight oil without and with random natural fractures (NFs). In our simulation, the pressure varies widely from the beginning to the end of the development. In real situation, tight oil reservoirs have high initial pressure and adopt step-down bottom hole pressure development strategy where the bottom hole pressure of the last stage is below the bubble point pressure and the free gas appears in the reservoir. Modeling studies indicate that the geometry of fracture has a great influence on the pressure and saturation profiles in the area near the fractures, and dissolved gas flooding contributes to the development of tight oil, and NFs can significantly improve production, while the effect of the stress sensitivity coefficient of NFs on production is more significant in the later stage of production with lower reservoir pressure.
Highlights
Along with the increasing social and economic development of world, the demand for energy is getting larger and larger
The hydraulic fractures (HFs) are considered as oval shape in 3D reservoirs, and fractures are allowed to be not perpendicular to the border of reservoir, so it is complex to generate 3D unstructured cells by discrete fracture models (DFMs)
An embedded discrete fracture models (EDFMs) simulator is developed to study the development of multi-stage horizontal wells in tight reservoirs
Summary
Along with the increasing social and economic development of world, the demand for energy is getting larger and larger. Dual continuum models are only suitable for the reservoir with a large number of highly connected and small fractures (KarimiFard and Firoozabadi, 2003). They may have difficulties representing highly localized anisotropy in reservoirs (Moinfar et al, 2013). Compared to DFMs, embedded DFMs have simpler mathematical algorithms for generating grids and will not generate many refined grids when fractures have complex geometric features Based on such advantages, many scholars used embedded DFMs to simulate and research the flow phenomenon in the fractured tight reservoir. In order to reflect the actual development of tight reservoir, reservoirs have high initial pressure, and multistage fractured wells adopt the step-down BHP production strategy. We generate nature fractures in reservoirs to study the influence of nature fractures in the tight reservoir
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
