大孔道诊断和描述技术研究

Research on the diagnosis and description of wormhole.

孤东油田七区西油藏埋藏浅 ,储集层胶结疏松、渗透率高 ,粒度多为正韵律分布 ,在注水开发过程中出砂严重 ,特别是实施强注强采方案后出砂程度加剧 ,一些井间形成了特高渗透带 (即大孔道 )。采用实验模拟方法研究了大孔道形成的机理和影响因素 (油层渗透率、岩石胶结程度、流体黏度、开采速率 )。由于用示踪剂诊断大孔道不经济 ,所以提出了利用生产数据诊断、描述大孔道的方法。用灰色理论计算各种因素间的相关关系 ,以诊断大孔道的存在 ;并利用简化的数学模型 ,计算大孔道参数(方向、厚度、渗透率、孔喉尺寸等 )。编制了具有以上功能的软件 ,利用该软件解释孤东油田七区西油藏 42井组单元的油、水井 2 90井次 ,诊断出 1 2 4口井存在大孔道 ,与实验区块示踪剂实验结果吻合。图 1表 1参

The western Unit 7 in Gudong oil field is a shallow oil reservoir with loosened consolidation and high permeability. Its depositional cycles are mainly positive rhythm. Sand production occurs during waterflooding. Especially after the enhanced water injection and enhanced production project was carried out, sand production become serious. Very high permeable zone comes into being between wells, which is called wormhole. The mechanism and influencing factors (reservoir permeability, consolidation degree of rocks, fluid viscosity, production rate) of forming wormhole were studied by modeling and doing experiments. Diagnosis and description of the wormhole were done by using the production data because of high cost of tracer. The interrelation between different factors was calculated by using Gray theory to diagnose the existence of the wormhole; and parameters of the wormhole (direction, depth, permeability, size of throat, etc.) are worked out by use of simplified math model. All above mentioned functions are carried out in the software. This software is applied to the explanation of information from oil/water wells (totally interpreted 290 wells/times and 42 wells/units) in western Unit 7 of Gudong oil field, and wormholes are found out in 124 wells. The result is identical with that of the tracer experiment in pilot test unit. This software is characterized by low cost, convenience and practicality.