小河道薄砂层井震联合识别技术及应用——以大庆长垣西部AGL地区为例

Recognition technology integrating logging and seismic data for thin sand reservoir in narrow channel and its application:Taking the AGL area in western Daqing placanticline as an example

大庆长垣西部AGL地区萨零油层组发育三角洲前缘小型水下分流河道砂体储层。三角洲前缘为砂泥岩薄互层沉积,水下河道窄,砂体厚度小、相变快,河道砂体地震特征不清晰,储层预测困难。为此,提出小河道薄砂层井震联合识别技术。首先,结合井、震资料,在精细地层格架控制下,通过逼近地下地质结构的正演模拟,构建窄小河道砂体三种地震响应模式;然后,按照点→面→体的思路,由井标定水下窄小河道砂体地震反射特征,在平面上利用地震属性追踪河道边界和走向,在三维地震数据体上分析窄小河道的形成期次和演化规律,定性描述窄小河道的展布特征;最后,根据已知井目的层地震反射波形特征和砂岩厚度,应用关联度分析法,实现基于波形模式识别的河道薄砂层厚度定量预测。应用该技术研究成果在大庆长垣西部AGL地区TA2无井控制区块部署开发井9口,完钻后河道预测符合率达到100%,砂体厚度相对误差为9.6%,单井最高日产油4.1t,指导了老油田周边油气勘探与开发,达到了增储上产的目的。

A small-scale sand body reservoir develops in the subaqueous distributary channel in front of the delta in the Saling oil group of the AGL area in the western Daqing placanticline.The delta front witnesses the thin interbedded deposition of sand shale.The channel is narrow,and sand bodies feature thin thickness and fast sedimentary facies transition.These make reservoir prediction challenging.In response,this paper proposes a recognition technology integrating logging and seismic data for the thin sand reservoir in the narrow channel of the study area.First,three seismic response models are established for the sand bodies in the narrow channel through the analysis of the forward model close to the underground geologic structure with seismic data under the control of a fine stratigraphic framework.Then according to the sequence from point to plane and then to volume,we calibrate the reflection characteristics of sand bodies in the narrow channel with logging data,trace the boundary and trend of the channel with the seismic attribute in the plane,analyze the sedimentary period and evolution law of the narrow channel on the three-dimensional(3 D)seismic data volume,and qualitatively describe the distribution characteristics of the narrow channel.Finally,depending on the known seismic reflection waveform characteristics in wells and sandstone thickness,we perform the quantitative thickness prediction regarding the thin sand reservoir in the channel based on waveform pattern recognition with the correlation analysis method.This technology is applied to deploy 9 development wells in TA2 block without well control in the AGL area in western Daqing placanticline.After drilling,the consistency of channel prediction reaches 100%.The relative error of sand body thickness is 9.6%,and the maximum daily oil production of a single well reaches 4.1 t.This research is capable of guiding the hydrocarbon exploration and development in the surrounding areas of old oilfields and achieves the goal of increasing reserves and production.