大庆油田M2区块致密油藏缝网压裂直井初期产能预测

Initial productivity prediction of network fracturing vertical well in tight reservoir of M2 block,Daqing oilfield

致密油作为重要的非常规油气资源,其开发潜力巨大,是我国新的油气增长点。然而,储层致密、渗透率低、连通性差等极大地制约了致密油的有效开发。以大庆油田M2区块为例,针对储层物性差、产能差异大等问题,首先采用灰色关联方法对影响缝网压裂直井初期产能的主控因素进行了筛选和评价;在此基础上,综合考虑地质因素和工程因素,提出了一个新的产能综合系数,用以表征直井产能大小。通过多元回归方法,建立了适合于该区块缝网压裂直井初期产能的经验模型,单井平均预测精度在85%以上,区块整体预测精度在90%以上。研究发现,射开含油砂岩厚度、含油饱和度、砂液比和加砂量等是影响该区块缝网压裂直井初期产能的主控因素。考虑到该区块储层较薄,砂体发育连续性差,建议可射开有效厚度在15 m以上的储层,采用成本控制更优的直井缝网压裂方式进行致密油的前期开发。

As an important unconventional oil and gas resource,tight oil has great development potential and is a new oil and gas booming target in China.However,factors of tight reservoir,low permeability and poor connectivity greatly restrict the effective development of tight oil.Taking M2 block of Daqing oilfield as an example,aiming at the problems of poor reservoir physical properties and large productivity difference,the gray correlation method is adopted to screen and evaluate the main controlling factors that affect the initial productivity of network fracturing vertical wells.On this basis,after comprehensively considering geological and engineering factors,a new productivity comprehensive coefficient is proposed to characterize the productivity of vertical wells.Through multiple regression method,an empirical model suitable for the initial productivity prediction of network fracturing vertical wells in this block is established with an average prediction accuracy of over 85%for single well and an overall prediction accuracy of more than 90%for the block.It is found that the thickness of perforated oil-bearing sandstone,oil saturation,sand liquid ratio and sand amount are the main controlling factors affecting the initial productivity of network fracturing vertical wells in this block.Considering the thin reservoir and poor continuity of sand bodies in this block,it is suggested to shoot the reservoir with an effective thickness of more than 15 m,and adopt the vertical well network fracturing method with better cost control for the early development of tight oil.