地质科技通报 (Sep 2021)
Inversion of time-frequency electromagnetic well seismic modeling to probe the inner structure of deep volcanic reservoir: A case study of LD area in Bohai Bay Basin
Abstract
The seismic reflection of volcanic reservoir in deep basin is disorderly due to the influence of energy shielding, which makes the exploration of volcanic reservoir very difficult. Aimed at the complex inner structure of deep volcanic reservoir with multi-phase superposition, the optimal offset, time-frequency electromagnetic acquisition technology of the excitation period window, time-frequency electromagnetic well seismic joint modeling inversion and electrical variation rhythm coding volcanic period interpretation technology are studied, which effectively improved the depth resolution and the recognition ability of the method. The research and application effect in LD area of Bohai Bay Basin are obvious. The results show that the volcanic eruptions of the third member of Shahejie Formation in the Red Star tectonic belt show the characteristics of "two strong three weak" of "weak-strong-strong-weak-weak" from bottom to top. Two volcanic eruption mechanisms are developed, which jointly control the distribution of volcanic reservoir facies in five periods. In Taoyuan structural belt, the volcanic eruption intensity of each stage of the third member of the Shahejie Formation is significantly weakened, and only one volcanic eruption mechanism is developed. Except for the relatively large distribution range of volcanic reservoir facies in stage 3, the volcanic rocks in other stages are mainly confined to the crater, mainly in eruption facies, and their scale is significantly reduced. The follow-up drilling results confirmed that the distribution of volcanic reservoir revealed by time-frequency electromagnetic was correct, which provided strong support for the large oil and gas discovery in this area and provided a successful example and technical methods for the detection of similar complex targets.
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