断层封闭性研究方法评述

A comment on research methods of fault sealing capacity

断层在油气藏形成过程中起重要作用,因此对其封闭性进行研究显得尤为重要。研究断层封闭性的方法很多,但还没有一种可适用于所有地区断层封闭性研究的方法,所以需要根据不同地区的基础资料来选取与其相适应的方法,以此来提高结果的可靠性。全面概述了近几年国内外研究断层封闭性的主要思路和方法,并对这些方法所需的基础资料、关键步骤、优缺点、适用范围和应用效果进行了分析。断层封闭性研究的定性评价参数主要涉及断裂方向、断距大小及断移地层砂地比等方面;定量评价参数主要涉及断面正压力、泥岩涂抹因子和泥岩流体超压等方面。目前使用最多的研究方法是以Yielding提出的断层泥比率(SGR)为基础,在选取合适的方法后,通过研究区及邻近地区的已知断层来确定所采用方法中的地区参数或评价标准,进而评价研究区的断层封闭情况。

Fault plays an essential role in oil and gas accumulation, so the analysis of fault sealing capacity is quite important. There are many methods, but it＇s still so hard for these methods to evaluate the fault sealing capacity accurately and widely. As a result, before we select an appropriate method and hence improve the reliability of results, we must make clear about the using condition and the key steps of different methods. This paper summarized the most frequently-used methods and their trains of thought proposed by the academician at home and abroad, and then analyzed the relevant basic datasets, key steps, merits and demerits, using conditions and the relative reliability of each method. The qualitative evaluation of fault sealing capacity has 12 respects, including direction of faults, size of faults throw, sand/strata ratio and so on. While the quantitative evaluation methods are mainly based on quantitative calculation of the normal stress on fault plane, shale smear factor and fluid pressure of mudstone. Presently, the SGR method put forward by Yielding is most mature and widest used in many methods. From the known area or some other area with similar geological character nearby, we can get the appropriate parameter or the evaluation standard of the special method, and then the unknown fault sealing capacity can be analyzed.