Abstract:

A two-dimensional scaled high-temperature-high-pressure (HTHP) physical model of steam flooding for horizontal well was developed. Horizontal well steam flooding mechanisms of different development stages were studied based on the A block in Shengli oil field. The effects of reservoir pressure, bottomhole steam dryness and gas injection strength on horizontal well steam flooding were also carried out. Physical model experiment results show that the whole process of steam flooding is divided into three stages: water extraction stage, steam effectively displacement stage and steam breakthrough stage. Steam chamber expands to the horizontal direction in water extraction stage. Steam chamber expands to both vertical and horizontal directions in steam effectively displacement stage, horizontal displacement is the dominator and vertical drainage is supplemented. Steam chamber continues to expand upward, vertical drainage is the dominator and achieves the overall development in late steam breakthrough stage. The recovery of steam driving at 5 MPa is higher than that at 7 MPa. The bottomhole steam dryness of steam flooding should not be less than 0.4. The higher steam dryness, the better is it for the development of horizontal well steam flooding. Temperature field is the most expansive and expanding when steam injection intensity is 1.9 t/ (d·ha·m). Meanwhile, improving the dryness of steam flooding for horizontal wells could achieve the effective development under high pressure conditions. The above experimental results gave a good direction to the development of A block in Shengli oil field ultra-heavy oil reservoir for horizontal well steam flooding, and achieved obviously development effect. The research has important guiding significance to develop similar heavy oil and ultra-heavy oil reservoir by steam flood with horizontal well.

Key words: ultra-heavy oil, horizontal well, steam flooding, oil-displacement mechanism, physical simulation experiment