应用分形几何法预测珠江口盆地白云凹陷有利成藏区

An application of fractal geometry to predict favorable area of hydrocarbon accumulation in Baiyun sag,Pearl River Mouth basin

利用分形几何法求得的断裂分维值是断裂数量、规模、发育程度、组合方式及动力学特征的综合体现,用其可定量描述断裂分布的复杂性和构造演化的成熟度。断裂的分维值越高,断裂连通性越好,在一定范围内有利于流体流动汇聚和油气藏的形成。依据白云凹陷断裂性质及平面分布特点,将研究区划分为4个断裂区域,并对所求得的各断裂区域T3及T5两个层面分维值与油气分布的关系进行了分析。白云凹陷断裂体系的空间分布具有良好的分形特征,其西南控洼断裂区域(Ⅳ区域)在T3及T5两个层面的断裂分维值均最大,断裂构造发育,推测极有可能成为白云凹陷一个新的勘探目标区。

The fractal dimension of faults calculated from fractal geometry is a comprehensive function of the faults＇ number, size, development, assemblage pattern and dynamics, and can be used to describe complexity of fault distribution and maturity of structural evolution. For a set of faults, the higher their fractal dimension, the better their connectivity, and the faults with a higher fractal dimension may be helpful to fluid concourse and hydrocarbon accumulation within a certain volume. Baiyun sag has been divided into four faulted areas according to its fault nature and lateral distribution, and the relationships between fractal dimensions on T3 and T5 horizons and hydrocarbon occurrence have been analyzed for each of the faulted areas. The space distribution of fault systems in Baiyun sag is quite good in fractal characterization, and the southwest sag-controlled faulted area （Area IV） has the highest fractal dimensions on T3 and Ts horizons, which may possibly become a new exploration target due to its developed fault structures.