Densified sandstone air layer identification evaluation method free from influence of frame

Abstract

The invention discloses a densified sandstone air layer identification evaluation method free from the influence of a frame. The method comprises: performing array sonic logging in wells in an area, according to the standard process of array sound wave data processing, performing calculating and analyzing, and solving a volume compression coefficient and a Poisson's ratio curve; for a ground layer with a similar lithology, according to the relative mirror image relation between the volume compression coefficient and a Poisson's ratio, identifying the fluid property of a storage layer by use of a superposition method; for a ground layer with a quite large lithology difference, according to a photoelectric absorption cross section index PE, mud quality content, and other lithology component contents, performing frame influence eliminating correction, reconstructing the relative mirror image relation between the volume compression coefficient and the Poisson's ratio, and accordingly, performing identification on the fluid property of the storage layer; and constructing a "mechanical characteristic parameter interpretation template" suitable for the local area, and performing fluid property identification on different lithology storage layers. According to the invention, the frame influence eliminating correction is carried out on the different lithology storage layers, so that the fluid property identification accuracy of the storage layer is improved.

Description

technical field [0001] The invention relates to the field of natural gas exploitation, in particular to a method for identifying and evaluating tight sandstone gas layers affected by de-framework. Background technique [0002] Tight sandstone gas layers refer to those containing natural gas underground, with low porosity (generally less than 10%), high water saturation (more than 40%) and permeability (less than 0.1 × 10%). -3 μm 2 ) sandstone layers that are barely able to seep natural gas. Because such sandstone layers are often located in deep or deep basins, they are often referred to as deep tight sandstone gas layers. There are a large number of tight sandstone gas layers in China. With the deepening of exploration and development, the identification of such gas-bearing reservoirs has attracted more and more attention. However, conventional logging data encounters great difficulties in solving such problems. Effective identification and evaluation of sandstone gas l...

AI Technical Summary

Problems solved by technology

[0003] At present, conventional logging data are used to identify and evaluate gas reservoirs, mostly using response characteristic method, three-porosity overlap / difference / ratio method, porosity-resistivity intersection method, irreducible water saturation method, apparent formation water resistivity method, etc. But for tight sandstone gas layers, due to the extremely limited storage space, the resistivity and porosity data are greatly affected by the rock skeleton, the fluid contributes little to its response characteristics, and the fluid information contained in the logging curve is less. Therefore, these methods are not suitable for low The identification of tight sandstone gas layers with pores and low permeability is inaccurate; the conventional method of gas layer identification using dipole acoustic logging data mostly selects parameters such as P-S wave time difference, energy, amplitude, elastic modulus, etc., and uses cross plots, difference ratios, Intuitive qualitative interpretation methods such as overlapping display and baseline value difference, selection of identification parameters is single, and mechanical feature information in logging data is not fully exploited, resulting in a high misjudgment rate in reservoir fluid identification, which makes tight sandstone gas formations further interpreted Increased uncertainty in evaluation

Images