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BP公司出砂预测技术将出砂分为三个阶段:初始阶段、瞬态出砂、稳定出砂。例如,在易于出砂的地层中,当井内压差增大时就出现出砂现象(初始阶段),其后将会持续几个小时、几天或几个月的大量出砂。最终地层出砂量递减为1～100pptb范围内的基础水平(稳定出砂)。最近公司在瞬态出砂和稳定出砂两个阶段取得阶段性进展,现在可以预测地层初始出砂时机,以及油井生产过程中任一阶段的出砂量,甚至对注水井出砂也可以做出预测。建立应力模型对初始出砂进行预测。这种模型基于对油田现场应用的研究,有点保守。一种应用是对关井期间的水井进行出砂预测,结果是不进行防砂控制。另一种是根据毛管内聚力理论,对高温高压气藏的延迟出砂进行解释。建立有限元模型对瞬态出砂进行预测。这种模型已经在实验室和现场试验中对出砂量进行了成功预测。利用有限元模型可以判断对生产井和注水井的产出砂能否进行控制。最后,对井筒内砂堵造成地层流体静压力升高而引起的油井井喷是否会枪毙油层做出预测。稳定出砂模型是建立在实验室内大量岩心出砂试验基础之上的纯经验模型。此模型在近海油田的出砂预测方面得到了应用。其应用结果是:可以采用具有很大经济优势的地面防砂,而不需要井下防砂。最后,提供一个应用以上三种模型对初始出砂、瞬态出砂、稳定出砂进行综合预测分析的实例,其预测结果与现场实际观察非常吻合。
BP sand production forecasting technology will be divided into three phases of sand: the initial stage, the transient sand production, stable sand. For example, in sand-prone formations, sand appears as the pressure difference in the well increases (initial stage), after which time a large amount of sands will last for hours, days or months. The amount of sand produced in the final formation is reduced to a level within the range of 1 ~ 100pptb (stable sand production). Recently, the company has made staged progress in both transient and steady sand production. Now it is possible to predict the timing of the initial sand production in the formation and the amount of sand produced at any stage in the production of the well, even for sand production in the injection well prediction. Establish a stress model to predict the initial sand production. This model is somewhat conservative based on the field application of the field. One application is for sand production prediction of wells during shut-in, with the result that sand control is not implemented. The other is based on capillary cohesion theory, delayed interpretation of high temperature and pressure gas reservoir sand. Establish finite element model to forecast transient sand production. This model has successfully predicted sand production in both laboratory and field tests. Finite element models can be used to determine whether production sand production wells and injection wells can control the output. Finally, a prediction is made as to whether or not a well blowout caused by sandstone plugging caused by increased hydrostatic pressure in the formation will shoot the reservoir. The stable sand model is a pure empirical model based on a large number of core sand tests in the laboratory. This model has been applied in the prediction of sand production in offshore oilfields. The result of its application is that it is possible to use surface sand control with great economic advantages without the need for sand control downhole. Finally, an example of comprehensive prediction and analysis of initial sand production, transient sand production and steady sand production by using the above three models is provided, and the prediction result is in good agreement with the actual observation in the field.