Fracture Identification Method and System for Tight Sandstone Formation

Abstract

The invention discloses the crack identification method and system of tight sandstone formation. The method comprises the following steps of based on deep induction logging data and medium induction logging data, acquiring a deep induction response value and a medium induction response value and acquiring a deep induction response average value and a medium induction response average value; basedon the deep induction response value, the medium induction response value, the deep induction response average value and the medium induction response average value, acquiring a first regression coefficient; based on the first regression coefficient, the deep induction response average value and the medium induction response average value, acquiring a second regression coefficient; based on the deep induction response value, the medium induction response value, the deep induction response average value, the first regression coefficient and the second regression coefficient, acquiring a doubleinduction difference coefficient; and setting a threshold, comparing the threshold and the double induction difference coefficient and identifying a crack. In the invention, through calculating the double induction difference coefficient and comparing with the threshold, a high angle crack in tight sandstone can be effectively identified, and the identification is not affected by changes in formation lithology, a physical property, oiliness and the like.

Description

technical field [0001] The invention relates to the field of petroleum exploration and development, and more specifically, to a method and system for identifying fractures in tight sandstone formations. Background technique [0002] At present, in terms of logging technology, imaging logging is the best way to identify and evaluate fractures, but this method is expensive and time-consuming, and is only used in some key exploration wells. Conventional logging is most widely used in oil exploration and development. Well curves have been used to identify fractures in reservoirs for decades. Logging scientists use various logging response characteristics of fractures to construct a series of the most basic fracture identification parameters, such as the three-porosity ratio method, secondary Porosity index method, borehole relative anomaly method, resistivity invasion correction difference ratio method, etc. These methods are more suitable for high-resistivity tight layers such ...

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Problems solved by technology

However, thin interbeds are developed in tight sandstone formations, relatively low resistivity, large matrix pores, and mainly high-angle fractures, and the fracture response is weak. Not all are applicable, and dual induction logging is commonly used in tight sandstone formations, and the measurement principle is quite different from that of dual laterologging used in high-resistivity tight formations such as carbonate rocks and igneous rocks, which further leads to tight sandstone formations. The accuracy of crack identification is low

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