Technology and Research on Improving Oil Recovery by Volume Fracturing with Phase Change Permeability in Ultra-low Permeability Reservoirs

Abstract The conventional water injection development production wells in ultra-low permeability reservoirs have low efficiency, low production and low liquid content, and poor economic benefits. Traditional water drive development techniques are difficult to adapt to the requirements of economically effective development in ultra-low permeability reservoirs. Therefore, it is urgent to adjust development ideas and transform water injection development methods. A major development experiment was carried out in the Y284 area of Huaqing Oilfield to transform the water injection development method. Based on the mechanism of reverse osmosis flooding in oil recovery wells, this article uses dynamic monitoring technologies such as downhole microseismic to achieve three-dimensional reservoir transformation, and establishes a large-scale fracturing technology of “collaborative permeability flooding, volume fracturing, and multi-stage temporary plugging” for reverse osmosis wells in ultra-low permeability reservoirs. Research has shown that large-scale fracturing technology for water injection wells can improve single well oil recovery speed by increasing the complexity of fracture networks. The important factors affecting the effectiveness of water injection wells include reservoir properties, fracturing transformation scale, cumulative water injection volume, remaining oil distribution, and heterogeneity of aquifers. At the same time, the construction parameters of large-scale volume fracturing for water injection wells, namely 140-170m, are quantitatively determined based on the actual situation of the mining field ³ The amount of sand added, a sand ratio of 17-22%, and a large displacement of 8-10m3/min, 1400-2000m ³ The amount of liquid entering the ground can most effectively achieve the conditions for reservoir transformation. The conclusion is that large-scale fracturing technology for conversion wells provides technical support for volume fracturing and optimization design of fracturing parameters for low production wells in ultra-low permeability reservoirs, and can provide guidance and reference for the efficient development of other similar ultra-low permeability reservoirs.