松辽盆地中央隆起带基底岩性预测

松辽盆地是我国东北部陆相油气型盆地，作为大庆油田勘探开发的新板块，基底地质条件复杂，古中央隆起内幕结构、构造特征认识不清，导致人们对基底岩石的构成存在分歧。利用最新二维地震剖面、测井和重磁数据，对松辽盆地古中央隆起带基底进行重磁、地震联合研究，从而确定中央隆起带基底岩石岩性。通过测井数据与地震属性等方法预测并假设侵入岩体为花岗岩。在地质系统的基础上，构建正演模型来进行地震正演模拟，模拟了地震子波激发得到的炮点记录及偏移剖面。根据收集的重力磁力资料，分析研究了中央隆起带的重力场特征及重力场的地质意义，推断了中央隆起带的断裂构造体系，以地震为约束条件通过建立基底侵入体平均密度值与布格重力异常的地质—地球物理模型，以2条地震成果来约束重力异常剖面继而进行拟合解释。研究结果表明，地震正演模拟的时间剖面与实际地震剖面较一致且花岗岩的同相轴与地震剖面侵入岩体同相轴强弱相吻合。中央隆起带地质构造复杂，主要断裂发育在南北、北北东向，控制着中央隆起带内地层的发育，次要断裂发育在东西、北西向，规模相对较小，控制了中央隆起带内局部凸起的范围。拟合试算得到的重力与磁力异常曲线和实测重力与磁力异常曲线相吻合，确定侵入体的密度为2.58 g/cm3左右。综合表明，基底侵入岩岩性为花岗岩。

Prediction of basement lithology in central uplift belt of Songliao Basin

The Songliao Basin is a continental oil and gas basin in northeastern China.As a new plate for exploration and development of the Daqing Oilfield，the basement geological conditions are complex，and the inner structure and structural characteristics of the paleocentral uplift are unclear，which leads to differences in the composition of basement rocks.Using the latest two-dimensional seismic profile，logging，and gravity and magnetic data，a combined gravity，magnetic and seismic study of the basement of the ancient central uplift in the Songliao Basin is carried out to determine the lithology of the basement of the central uplift.It is predicted and assumed that the intrusive rock mass is granite through methods such as logging data and seismic attributes.On the basis of the geological system，a forward modeling model was constructed to simulate the seismic forward modeling，and the shot point records and offset profiles obtained from seismic wavelet excitation were simulated.According to the collected gravitational magnetic data，the characteristics of the gravity field of the central uplift zone are analyzed and studied，the geological significance of the gravity field is studied，and the fault structure system of the central uplift zone is inferred.The average density of basement intrusions is established by establishing average density of basement intrusions and the geological-geophysical model of Bouguer gravity anomaly uses two seismic results to constrain the gravity anomaly profile and then perform fitting interpretation.The research results show that the time profile simulated by the earthquake forward modeling is relatively consistent with the actual seismic profile，and the granite phase axis is consistent with the seismic profile intrusive rock body phase axis.The geological structure of the central uplift belt is complex.The main faults are developed in the north-south and north-north directions，which control the development of the strata in the central uplift belt.The minor faults are developed in the east-west and northwest directions and are relatively small in scale，which control the central uplift.The range of local protrusions in the band.The curves of gravity and magnetic anomalies obtained by fitting trial calculations are consistent with the measured gravity and magnetic anomaly curves，and the density value of the intrusive body is determined to be about 2.58 g/cm3.Comprehensively show that the lithology of the basement intrusive rock is granite.