Numerical Investigation of Major Impact Factors Influencing Fracture-Driven Interactions in Tight Oil Reservoirs: A Case Study of Mahu Sug, Xinjiang, China

Abstract

Fracture-driven interactions (FDIs) in unconventional reservoirs significantly affect well production and have thus garnered extensive attention from the scientific community. Furthermore, since the industry transitioned to using large completion designs with closer well spacing and infill drilling, FDIs have occurred more frequently and featured more prominently, which has primarily led to destructive interference. When infill wells (i.e., “child” wells) are fractured, older, adjacent producing wells (i.e., “parent” wells) are put directly at risk of premature changes in production behavior. Some wells may never fully recover following exposure to severe FDIs and, in the worst case scenario, will permanently stop producing. To date, previous investigations into FDIs have focused mainly on diagnosis and detection. As such, their formation mechanism is not well understood. To address this deficiency, a three-dimensional, multi-fracture propagation simulator was constructed based on the unconventional fracture model (UFM) and applied to a system that included both an older, adjacent passive well (“parent” well) and an active well (“child” well). Herein, the theoretical framework for overall complex fracture modeling is described. Furthermore, numerical simulation results are presented, demonstrating the critical roles of in-situ stress distribution and pre-existing natural fractures and aiding in the development of appropriate strategies for managing FDIs.

Comprehensive Numerical Evaluation of CO2 Huff-n-Puff in an Offshore Tight Oil Reservoir: A Case Study in Bohai Bay Area, China

“…The 2 and the constant composition expansion (CCE) experimental results are shown in Figure 5. The oil viscosity and density at the initial formation conditions are 0.3291 mPa•s and 0.8205 g/cm 3 , respectively. The bubble point pressure is 28.509 MPa.…”

“…1 With this basis, for offshore unconventional reservoirs, the economic development has been received increasing attention. 2,3 Since the oil recovery factor in tight oil reservoir is typically below 10% in the primary production, 4 CO 2 injection has been considered as an enhanced oil recovery method to improve the performance in tight oil reservoirs. Usually, the waterflooding method is more economical; however, compared with gas injection, water injection is not suitable due to weak mobility, poor injectivity, and high viscosity.…”

“… 1 With this basis, for offshore unconventional reservoirs, the economic development has been received increasing attention. 2 , 3 …”

“…In recent years, China’s onshore tight oil reservoirs characterized by ultralow porosity (<10%) and low permeability (<0.1mD) have been effectively developed . With this basis, for offshore unconventional reservoirs, the economic development has been received increasing attention. , …”

An Overview of Recent Developments and Understandings of Unconventionals in the Vaca Muerta Formation, Argentina

“…To circumvent the detrimental interplay between parent and child wells, one of the key mitigation strategies involved pressurizing the parent well with water [50,51]. The objective was to sustain the productivity of the parent well, even as new adjacent child wells were drilled and fractured.…”