We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
潜山裂缝型凝析气藏注气开发机理.
- Authors
张利军; 赵林; 谭先红
- Abstract
To guide the effective development of buried-hill fractured condensate gas reservoirs, in this paper, the experiments of gas injection into long cores and vertical-profile models are performed, which aims to study mechanisms of gas injection in terms of oil displacement efficiency and vertical sweep efficiency for buried-hill fractured condensate gas reservoirs, respectively. Results show that, for the depleted development, the oil recovery of fractured formation is higher than that of non-fractured homogeneous formation at early stage (>32 MPa), but turns to be lower at mid-late stage (<32 MPa). Under the maximum condensate pressure (23 MPa) and abandonment pressure (5 MPa), fractures reduce the recovery rate of condensate oil by 1.37% and 4.77%, respectively. Injecting gas at maximum condensate pressure increases the recovery rate of condensate oil by 20% for homogeneous formation, and is not closely related to permeability. Affected by gas channeling, the recovery rate of condensate oil increases by 13.7% for fractured formation. During the gas-injection, the fractured formation presents two types of gas channels, i.e., fracture and matrix-fracture, which is inferred from the dual-step pattern in gas-oil ratio curve whose inflection points are 0.4 HCP and 1.4 HCPV, respectively. The oil recovery increases significantly during gas injection, but is essentially coincidence with that in the full-time depletion during the subsequent depletion stage. Combining the gas-injection PVT experiments, it is proposed that the pressure maintaining and oil displacement, serve as the main mechanisms for improving oil displacement efficiency. In terms of the gas injection timing, the effect of high-pressure gas injection is significantly better than that of low-pressure gas injection for non-fractured reservoirs. As for fractured reservoirs, the impact of gas injection timing is not significant. In terms of vertical sweep efficiency, the barrier of the non-fractured reservoir has a certain obstruction effect on the gravity differentiation, but the gravity-drive characteristics is obvious in general with the highest gas-drive degree at reservoir top. The high-dip fractures in buried-hill reservoirs hinder the lateral flow of injected gas from injectors to producers. The gravity-drive characteristics is relatively weak, and no obvious low-saturation zone is formed. The gas-drive degree in the middle section is the highest. This study will provide effective guidance for the design of gas injection plans and dynamic tracking adjustments for buried-hill fractured condensate gas reservoirs.
- Subjects
GAS condensate reservoirs; GAS injection
- Publication
Natural Gas Geoscience, 2024, Vol 35, Issue 2, p357
- ISSN
1672-1926
- Publication type
Article
- DOI
10.11764/j.issn.1672-1926.2023.08.012