川中龙女寺地区龙王庙组沥青质储层分布预测

Distribution Prediction of Asphaltene Reservoir of Longwangmiao Formation in Longnyusi Area,Central Sichuan

以四川盆地龙女寺地区龙王庙组为例探讨沥青质储层岩石物理分析以及地震预测方法。实际地层中沥青质主要以液态形式赋存于储集空间中,分布复杂,容易堵塞孔喉通道、降低储层有效空间,导致储层连通性变差。虽然沥青质岩石与围岩的物理特征差异较大,但是地层中沥青质含量少,仅占1.08%~4.56%,因此,沥青质对储层岩石物理特征影响较弱,导致含沥青质储层预测难度大。基于岩石物理实验以及测井曲线重构,开展储层段岩石物理分析,发现纵、横波速度比能够有效识别沥青质储层;利用叠前反演技术得到纵、横波速度比的数据体开展沥青质储层预测。实际应用证实,该方法进行沥青质储层预测结果与新完钻井测井解释的沥青质储层厚度吻合度较高,表明研究区存在一套沥青含量在2%以上、平均厚度达20 m的沥青质碳酸盐岩储层。该方法实现了沥青质碳酸盐岩气藏定量评价,对此类沥青质储层预测具有参考价值。

Taking Longwangmiao formation in Longnyusi area of Sichuan basin as an example,the petrophysical analysis and seismic prediction methods of asphaltene reservoir are discussed.In the actual formation,asphaltene mainly exists in the reservoir space in the form of liquid,and its distribution is complex.It is easy to block the pore throat channel,reduce the effective space of the reservoir,and cause the poor connectivity of the reservoir.Although the physical characteristics of asphaltene rock are quite different from the surrounding rock,the asphaltene content in the formation is only 1.08%~4.56%,so the asphaltene has a weak impact on the physical characteristics of the reservoir rock,which makes it difficult to predict the asphaltene reservoir.Based on the petrophysics experiment and the reconstruction of logging curve,the petrophysics of the reservoir section is carried out.It is found that the velocity ratio of P and S waves can effectively identify the asphaltene reservoir.The prestack inversion technology is used to obtain the data volume of the P/S wave velocity ratio to carry out the asphaltene reservoir prediction.The actual application confirms that the prediction results of asphaltene reservoir by this method are in good agreement with the thickness of asphaltene reservoir interpreted by newly completed well logging.It indicates that there is a set of asphaltene carbonate reservoir with asphalt content of more than 2%and average thickness of up to 20 m in the study area.This method realizes the quantitative evaluation of asphaltene carbonate gas reservoirs,and has reference value for the prediction of such asphaltene reservoirs.