低渗油藏宽带压裂中仪表压力梯度信号提纯技术  

Purification Technology for Instrument Pressure Gradient Signals in the Broadband Fracturing of Low Permeability Reservoir

作　　者：吴震 吴帅[1] WU Zhen;WU Shuai(No.1 Oil Production Plant,CNPC Changqing Oilfield Co.)

机构地区：[1]中国石油天然气股份有限公司长庆油田第一采油厂

出　　处：《化工自动化及仪表》2024年第4期665-670,共6页Control and Instruments in Chemical Industry

摘　　要：针对渗透率很低的油藏,在水平井注气过程中,水平井与裂缝布井方位、水平井层位、减氧空气氧气含量、注气速率等参数,会对油藏水驱的启动压力梯度信号形成干扰,影响后期驱油效果,也会影响低渗油藏宽带压裂作业的安全性的问题,提出一种仪表压力梯度信号提纯技术,设计存在干扰下的压力梯度拟合方法,利用拟合因子提取信号特征;油藏的压力梯度-外部干扰曲线在梯度下降阶段是一条上凹型曲线,利用其非达西渗流特征,设计cost函数实现对仪表信号数据集的代价函数求解,完成拟合;分解分量,根据流体在地层中形成侧向线性驱替规律,获取压力梯度信号的自适应谱;在外部干扰条件下获取最佳旋转角,推导获得直达波信号完成信号提纯。实验证明:该方法针对低渗油藏宽带压裂中仪表的压力梯度信号提纯效果好,而且波形没有失真,确保了提纯精度。For reservoirs with very low permeability and the gas injection occurs in the horizontal well,the parameters like the horizontal well and fracture distribution,horizontal well position,oxygen content in the oxygen-reduced air,and the gas injection rate will interfere with the startup pressure’s gradient signals of reservoir water flooding,and affect the effect of later oil flooding,and also influence the safety of broadband fracturing operation in low permeability reservoirs.In this paper,a purification technology for the instrument pressure gradient signal was proposed and a pressure gradient fitting method under interference was designed,including making use of the fitting factor to extract signal features.Considering upper concave of the reservoir’s pressure gradient-external interference curve in the gradient descent stage,having the non-Darcy flow characteristics based to design cost function was implemented to solve the cost function of the instrument signal’s data set and complete the fitting operation.Through decomposing pressure gradient signal’s component of the instrument,the adaptive spectrum of the pressure gradient signal was obtained according to the lateral linear displacement law of the fluid in the formation,including the optimal rotation angle obtained under the condition of external interference,and the direct wave signal was derived to complete signal purification.The experimental results prove that,the method has a good purification effect on the pressure gradient signals of the instrument in the broadband fracturing of low permeability reservoir,and the waveform is not distorted to ensure purification accuracy.

关 键 词：仪表压力梯度 信号提纯 低渗油藏 信号波形 稀疏特性 

分 类 号：TN958[电子电信—信号与信息处理]