Method and system for determining collapse events in fractured-vuggy reservoirs

Abstract

The invention discloses a method and a system for determining occurrence of a collapse accident in fracture-cave type oil reservoir karst cave. The method comprises the following steps: determining a producing well to be detected; acquiring a parameter of a producing well drilling karst cave and determining the critical span of the producing well drilling karst cave according to the parameter; when judging that the actual span is more than or equal to the critical span, determining that the collapse accident occurs in the producing well drilling karst cave. According to the method and the system, the influence of stratum pressure reduction on the karst cave collapse under the production condition of the producing well is completely taken into consideration, the karst cave collapse condition caused by stratum pressure reduction in the production process can be accurately predicted, prevention measures can be taken in advance, greatly reduced yield caused by the karst cave collapse is avoided, and effective basis is provided for stable yield of the producing well.

Description

technical field [0001] The invention relates to the technical field of development of fractured oil reservoirs, in particular to a method and system for determining collapse events of karst caves as formation pressure decreases during the production process of fractured-cavity reservoirs. Background technique [0002] In fracture-vuggy carbonate reservoirs, large karst caves are the main storage space, and fractures mainly play the role of communication and diversion. At present, oil wells drilled in fractured-vuggy reservoirs that encounter dissolved-vuggy reservoirs will experience a sharp decline in production during the production process. From the reservoir itself, this phenomenon is generally caused by two factors. The first factor is that the water cut rises rapidly due to the rise of the bottom water in the reservoir, and the second factor is the collapse of the drilled karst cave reservoir, which makes the passages such as large fractures close. For the second fac...

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Problems solved by technology

Specifically, the prediction methods in the prior art only analyze the influence of static parameters such as the shape, size, and roof thickness of the cave on the collapse, as well as the prevention and control of the collapse, and the factors affecting the collapse, without considering the formation pressure caused by oil well production. The impact of the decline on the collapse of the cave, it is difficult to predict the collapse of the cave during the production process

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