下寺湾油田延长组人工裂缝形态对压裂改造效果的影响

Effect of Artificial Fracture Morphology on Fracturing Effect in Yanchang Group of Xiasiwan Oil Field

下寺湾油田延长组储层中的裂缝分为天然裂缝和人工诱导裂缝。天然微裂缝包含岩芯裂缝和显微裂缝,其存在不仅对人工裂缝的形态具有一定影响,而且与人工裂缝一起可增强储层的导流能力、与注入水沟通引起含水上升快甚至水淹及压裂无效。利用FracPro PT10.3三维压裂软件,分别建立人工裂缝长度与压后累计产量关系曲线、人工裂缝高度与压裂后初期日产油量之间关系曲线、裂缝内充填的支撑剂的铺砂浓度与压后产量关系曲线。在综合考虑储层物性特征、开发井网及投资回报率的基础上,最终确定研究区人工裂缝半长优化后的结果为150-180 m、缝高不超过储层厚度的3倍、裂缝的宽度在0.8-0.9 cm左右。

The cracks in Yanchang formation of Xiasiwan oilfield are divided into natural cracks and artificial induced cracks. Natural microfracture consists of core and microscopic cracks, and its existence not only has a certain impact on morphology of artificial fractures, but also can strengthen diversion capacity of reservoir with the artificial fracture and cause the water cut rising, even water flooding and invalid fracturing with injection water. The curve of artificial crack length and cumulative output after fracturing, the curve of artificial fracture height and the initial daily oil production after fracturing and the curve of sanding concentration of proppant filled in the cracks and output after fracturing were established with Frac Pro PT10.3 three-dimensional fracturing software. On the basis of considering the characteristics of reservoir, development well pattern and return on investment, the following conclusions were drawn： the results of the half length of the artificial fracture in the study area are 150-180 m; fracture height is not more than 3 times the thickness of the reservoir; the width of the crack is about 0.8-0.9 cm.