多层合注封闭油藏注水井压降试井分析

Pressure Characteristics Analysis of Coalbed Methane Volume Fracturing Horizontal Well

对于复杂断块油气藏而言,砂体往往小、连片性差,但纵向上层数多,常规的单层注水模型已经不能准确的描述油藏的动态特征.为解决上述油藏的渗流问题,建立了多层合注外边界封闭油藏注水井不稳定渗流数学模型,模型中每一层的物性和边界大小各不相同.通过拉普拉斯变换,利用Stehfest数值反演对数学模型进行了求解,获得了多层合注条件下的井底压力响应特征曲线,并将曲线划分为六个阶段.研究表明主力层的砂体边界大小对井底压力动态影响较大;受多层干扰影响,用常规理论方法计算的边界大小有可能与实际地质情况不一致.

For complex fault block oil reservoirs,sand body scale is often small and not continuous,the conventional single layer water injection model cannot accurately describe the dynamic characteristics of the reservoir pressure.To solve the seepage problem of the reservoir,in this paper,we established a multilayer close outside boundary reservoir injection wells unstable seepage flow mathematical model,the physical properties of each layer in the model and boundary size each are not identical.By Laplace transform,Stehfest numerical inversion was used to solve mathematical model,bottom hole pressure response characteristic curve under the condition of the multi-layer was obtained and the curve was divided into six stages.Research shows that sand body scale of main layer boundary had a greater influence on the size of bottom hole pressure.Affected by multilayer flow interference,the size of theborder which calculated with the theory of conventional method may be inconsistent with the actual geological conditions.