白云凹陷西南潜山储层发育条件及裂缝预测技术研究

Research on Reservoir Development Conditions and Fracture Prediction Techniques of Buried Hill in Southwest Baiyun Sag

惠州26-6潜山勘探的成功,表明珠江口盆地具备潜山勘探潜力。白云凹陷西南基底在中生代为陆源岩浆弧,与惠州26-6基岩潜山具备相似的构造背景,已钻井钻遇岩性以花岗岩为主,具备潜山发育的物质基础。通过岩性分析、构造演化史、断裂活动期次分析明确潜山储层发育的主控因素,潜山岩性以脆性花岗岩为主,受多期构造运动的影响具备构造裂缝发育及后期活化的条件。基岩潜山经历长时间风化暴露剥蚀,多期构造裂缝为风化淋滤提供了通道,具备形成风化型储层的发育条件。建立早期挤压褶皱裂缝、晚期伸展断裂诱导裂缝的裂缝发育模式,在地质模型指导下,通过3Dmove软件实现构造裂缝的离散建模,形成一套离散裂缝的预测技术。研究表明,目标区基底以断裂诱导缝为主,潜山内幕裂缝更为发育,发育褶皱和断层相关裂缝的复合裂缝体系,具备更好的储层物性。

The success of Huizhou 26-6 buried hill exploration indicates that the Pearl River Mouth Basin has potential for buried hill exploration.The basement in southwest Baiyun Sag is a continental magmatic arc in the Mesozoic,which has a similar tectonic background to the Huizhou 26-6 bedrock buried hill.The lithology encountered by drilled wells is mainly granite,which is the material basis for the development of buried hills.Through lithology analysis,structural evolution history,and fault activity period analysis,the main controlling factors of the development of buried hill reservoirs are clarified.The lithology of the buried hill is mainly brittle granite,and it has the conditions of structural fracture development and later activation affected by multi-stage tectonic movement.The bedrock buried hills are exposed and eroded for a long time,and the multi-stage structural fractures provide channels for weathering and leaching,which is suitable for forming weathering reservoirs.The fracture development model of early compression fold fractures and late extension fracture-induced fractures is established.Under the guidance of the geological model,discrete modeling of structural fractures is realized through 3Dmove software,and a set of discrete fracture prediction techniques is formed.The research shows that the fault-induced fractures developed mainly in the basement of the target area,and fractures are more developed in the inner part of the buried hill.A composite fracture system of folds and fault-related fractures is developed,which has better reservoir physical properties.