渤海JZ油田D井区JZ-X井钻后断层模式与成藏规律研究

Study on the fault pattern and reservoir forming rules of JZ-X well post-drilling in D well area in Bohai JZ oilfield

渤海JZ油田内部断裂系统十分发育,由于部分断层的断距和地层倾角较大,断层附近成像复杂,局部构造形态和断裂系统解释可能存在多解性,给开发井的实施造成了较大风险。本文以JZ油田D井区为例,钻前认为该井区构造高部位边界大断层附近潜力较大,设计JZ-X井来进行评价。JZ-X井实钻情况与钻前预测差异较大,主要钻遇水层,无生产潜力。钻后分析认为钻前认识的连续地震同相轴其实是一种"层断轴不断"的假象,其实构造高部位存在一条封堵小断层将JZ-X钻遇位置分割成一独立小断块,且与构造低部位D井区主体块不连通,成藏条件差导致该井失利。通过对JZ-X井失利原因进行分析和思考,认为在大断层附近部署开发井要时刻保持敏锐的风险意识,需要做好精细的构造解释和充足的风险潜力预案,对相似油田在断层附近实施开发井具有较好的借鉴意义和启示。

Internal fault system of JZ oilfield in Bohai sea is very development. Due to the large fault distance and stratigraphic dip angle of some faults, imaging near fault is complex,and the local structural configuration and fault system interpretation may be multiple solutions, which poses the larger risk to the implementation of development wells. This paper takes well D of JZ oilfield as an example. Before drilling, it is believed that this well area has great potential near the large boundary fault in structural high part, and JZ-X well is designed for evaluation. The actual drilling situation of JZ-X well is significantly different from pre-drilling prediction, and the main drilled in water, without any production potential. The post-drilling analysis suggests that the continuous seismic event recognized before drilling is actually an illusion of "continuous reflection event but discrete layer".In fact, there is a small fault sealing in the high part of the structure, which divides the drill encounter of JZ-X into an independent small fault block, and is not connected with the main block of well D in the low part of the structure. By analyzing and considering the cause of the failure, it is concluded that keeping a keen sense of risk at all times in deploying development wells near large faults is necessary, detailed structural interpretation and sufficient risk potential plans are needed, which has a good reference significance and enlightenment for similar oilfields to implement development wells near faults.