| Popis: |
Bed He-1 and Shan-2 in Daniudi Gas Field are typical mud-sandstone interbeds. Controllable layer penetration fracturing technique is proposed to control extension of fractures in the formation without dry beds and water layers connected so to realize joint use of Bed He 1 and Shan 2. Combined with single well data, the thickness of the interlayer and the horizontal principal stress difference were compared and calculated to analyze the impact of barriers properties and controllable fracturing parameters on layer penetration fracturing. Involving factors like formation thickness and stress difference, the criteria of penetration fracturing is established and verified with temperature logging data. At last, an optimizing approach of controllable parameters on the basis of precise description of formation properties is proposed. Simulation results indicate that both barrier thickness and stress difference between pay zone and barrier would impede the vertical expansion of fractures. As a result, layer penetration fracturing is easy to conduct in formations with barriers less than 6 m in thickness and stress difference between pay zone and barrier smaller than 6 MPa. Besides, Parameters, involving fracturing fluid viscosity, injection rate and volume, the direction, location and diameter of perforation, should be optimized in hydraulic fracturing design. The established quantitative criteria in this paper is in good accordance with tested data. Such criteria serves as an important reference for fracturing optimization and design in similar wells, which is also a new trial for the stimulation of similar formations. |
