Method of judging low-resistivity annulus formed in formation

Abstract

The invention belongs to the technical field of petroleum exploration and development, in particular to an oil and gas reservoir recognition method applied to qualitatively analyzing existence of oil reservoirs through detection data, and provides a method of judging a low-resistivity annulus formed in a formation. The method includes: acquiring core data and determining irreducible water saturation Swb and residual oil saturation Sor of a core; acquiring a ratio of drilling fluid resistivity Rmf and formation water resistivity Rw according to the irreducible water saturation Swb and residual oil saturation Sor of the core; detecting a target formation to acquire the formation water resistivity Rw and the drilling fluid resistivity Rmf; if an actual physical value is larger than a calculated value, determining the low-resistivity annulus is formed. Through the application of the method in low-resistivity oil and gas fields, efficiency of exploiting low-resistivity oil and gas reservoirs can be improved effectively, the low-resistivity oil and gas reservoirs are recognized visually and quickly, exploration cost is reduced, and economic benefit is increased. As China possesses many low-resistivity oil and gas reservoirs, the method has promising application prospect.

Description

technical field [0001] The invention belongs to the technical field of petroleum exploration and development, and in particular relates to a method for identifying oil and gas reservoirs, that is, how to qualitatively analyze the existence of oil layers through detection data. Background technique [0002] In the technology of judging low-resistivity oil and gas layers, the low-resistivity ring refers to the resistivity of the flushing zone in the reservoir, the resistivity of the transition zone and the resistivity of the original formation. When the resistivity of the transition zone is the lowest, the transition zone of the reservoir is called low-resistivity. ring belt. When a low-resistance ring zone is detected in the formation, it means that there is oil and gas in the formation. This has long been confirmed by the logging community. Some people have also verified through experiments that during the process of mud invasion into the formation, there will be a low-resis...

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Problems solved by technology

However, due to the very strict conditions for the formation of low-resistivity rings, it cannot be guaranteed that every well will have low-resistivity rings if this method is not used. Other logging methods lead to increased exploration costs. The patent "A Method for Optimizing Drilling Mud to Quickly Identify Low-resistivity Oil and Gas Layers" proposes a mud design method, which cannot intuitively describe the relationship between mud resistivity and the conditions for forming low-resistance zones. , so the existing technology is not conducive to the exploration and development of low-resistivity oil and gas layers

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