疏松砂岩储层出砂风险综合预测新方法及其应用

New method to comprehensively predict the sand production risk for unconsolidated sandstone reservoirs and its application

油气井出砂是疏松砂岩储层生产过程中面临的最普遍、最严重问题,储层出砂风险的准确预测是有效预防出砂现象的关键技术手段之一。油井出砂受多种因素综合影响,单项预测技术考虑因素较单一,准确度有限,缺乏直观、综合的预判结果。结合疏松砂岩储层的出砂特点,采用模糊数学理论,建立了出砂风险综合预判模型。以声波时差法、组合模量法、斯伦贝谢指数法、实验法和现场观测法等5种常用方法为评价因素集,以“出砂”“可能出砂”和“不出砂”3种情况为评价集,结合各因素特点确定对应的隶属函数,采用层次分析法原理计算各因素权重模糊集,按“最大隶属原则”综合判断储层出砂风险。基于预判模型建立的疏松砂岩储层出砂风险综合预测新方法,成功指导了XF6-4油田的出砂风险预判和防砂方式选择与设计。实例应用表明,该方法考虑的因素更为综合全面,且可在方案设计时给出分析结果,对准确预判储层的出砂风险和合理选择防砂措施具有重要意义。

Sand production in the oil or gas well is one of the most common and serious problems faced in the production process of unconsolidated sandstone reservoirs,and the accurate prediction of the sand production risk is one of the key techniques for preventing sand production effectively.The sand production is comprehensively influenced by multi-factors.For single predicting technique,its considered factors are rather simple and its predicted accuracy is rather limited,thus the predicted results are not visual and comprehensive.Integrated with the sand production characteristics,with the help of fuzzy mathematics theory,the comprehensive prejudging model for the sand production risk was established.Taking the following five commonly used forecasting methods,i.e.interval acoustic time method,combined modulus method,Schlumberger index method,experimental method and field observation method as the evaluating factor set,regarding the three cases of“sand production”,“possible sand production”and“no sand production”as the evaluating set,combined with the characteristics of each factor,the corresponding membership function was determined,the fuzzy set of each factor weight was calculated by the principle of analytic hierarchy process(AHP),and the sand production risk of the reservoirs was comprehensively judged by the principle of“the maximum membership”.On the basis of the prejudging model,a new comprehensive predicting method of the sand production risk for unconsolidated sandstone reservoirs was established,which has successfully guided the sand production risk prediction and the sand control method selection and design in XF6-4 Oilfield.The field application shows that the factors considered in this method are more comprehensively and the analysis results can be given in the program design.All these achievements are of a great significance for accurately predicting the reservoir sand production risk and reasonably choosing the sand control measures.