摘要
勘探开发实践证实,四川盆地川西地区、塔里木盆地塔西南地区、准噶尔盆地南缘地区等山地复杂构造区油气资源丰富,是下步勘探开发的重要领域。为了提高山地复杂构造区叠前深度偏移初始速度模型与构造特征的匹配性,达到改善叠前深度偏移成像质量的目的,在常规约束速度反演基础上,通过形成构造约束的速度趋势函数和基于径向基函数薄板理论的三维空间速度网格重构函数,形成了山地复杂构造区叠前深度偏移初始层速度约束反演改进新方法。研究结果表明:①初始速度模型中保证速度连续性的同时,保留小尺度地质异常体速度响应,能有效提高速度建模精度;②通过沿自由边界的弯曲板进行速度网格重构可更好保留小尺度地质异常体的速度响应,可有效提高速度建模效率;③新方法通过构造约束的速度趋势函数较好剔除速度异常高频,减少速度更新求解时陷入局部最优;④新方法获得的初始速度模型与地质构造特征匹配较好,可有效改善叠前深度偏移成像质量,尤其是构造翼部或逆掩构造顶部成像质量。结论认为,建立的山地复杂构造叠前深度偏移初始层速度反演改进新方法,在复杂构造区域反演得到的层速度场更符合地质规律,对落实复杂构造展布及勘探目标有重要意义,有助于深入推进我国山地复杂构造区油气的勘探。
Practical exploration and development proves that there are abundant oil and gas resources in mountainous complex structure areas(e.g. western Sichuan Basin, southwestern Tarim Basin and southern marginal Junggar Basin), which are important fields for the next exploration and development. In order to improve the matching between the initial velocity model for pre-stack depth migration in mountainous complex structure regions and the structural characteristics and then improve the imaging quality ofpre-stack depth migration, this paper develops an improved constrained initial layer velocity inversion method for pre-stack depth migration in mountainous complex geological structure areas based on the conventional constrained velocity inversion by establishing the structure constrained velocity trend function and the three dimensional spatial velocity grid reconstruction function based on the radial basis function thin plate theory. And the following research results are obtained. First, the initial velocity model preserves the velocity response of smallscale geological anomalous bodies while ensuring the velocity continuity, so it can improve the accuracy of velocity modeling effectively.Second, reconstructing the velocity grid on the bend plate along the free boundary can better preserve the velocity response of smallscale geological anomalous bodies, so it can improve the efficiency of velocity modeling effectively. Third, the improved method can better eliminate the abnormal high frequency by using the structure constrained velocity trend function, so as to reduce the local optimum during velocity updating solution. Fourth, the initial velocity model established on the basis of the improved method is better matched with geological structural characteristics and it can improve the imaging quality of pre-stack depth migration effectively, especially at the structural flank or the top of over thrust structure. In conclusion, the layer velocity field in complex structure areas inverted by the improved constrained initial layer velocity inversion method for pre-stack depth migration in mountainous complex structure areas is more accordant with the geological laws, so the improved method is of great significance in confirming the distribution and exploration targets of complex structures, and is conducive to promoting oil and gas exploration in mountainous complex geological structure areas in China.
作者
熊晶璇
贺振华
刘鸿
赵容容
杨卫宁
张恩嘉
王光银
唐虎
XIONG Jingxuan;HE Zhenhua;LIU Hong;ZHAO Rongrong;YANG Weining;ZHANG Enjia;WANG Guangyin;TANG Hu(Chengdu University of Technology,Chengdu,Sichuan 610213,China;CNPC Bureau of Geophysical Prospecting INC.,Zhuozhou,Hebei 072750,China;CNPC Mountain Geophysical Technology Test Center,Chengdu,Sichuan 610213,China;Exploration Division,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China)
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2022年第5期47-55,共9页
Natural Gas Industry
关键词
山地
复杂构造
叠前深度偏移
地质构造约束
约束速度反演
改进速度趋势函数
速度模型重构
Mountainous area
Complex structure
Pre-stack depth
Geological structure constraint
Constrained velocity inversion
Improved velocity trend function
Velocity model reconstruction
