海底原位高分辨率二维时移地震探测系统设计

大规模开采海底天然气水合物存在地质灾害风险，因此需要对开采过程进行相关监测。时移 地震可以反演水合物分解引起的储层沉积物地震反射特性变化。该文首次基于高分辨率多道地震，提 出海底原位激发和采集的二维时移地震系统，给出了系统及主要组成部分的结构设计、流程设计和关 键参数设计，并对设计过程和相关依据进行详细论述。该系统主要由深水电火花震源、深水多基元接 收缆、多通道数据采集系统和电池组及其管理系统组成，同时还包括深水电机、深水电滑环、自动排 缆器等辅助机构。其中电火花震源最大激发能量为 1 000 J，接收缆采用 16 个耐压 20 Mpa 的深水检波 器构成，基元间距为 1 m，接收的地震子波经 16 通道采集卡处理后进行原位存储。系统由锂电池进行 供电，采用周期性唤醒的工作模式，设计水下工作 2 个月，每小时进行 1 次激发采集，最大工作水深为 1 500 m，最大地层穿透深度为 250 m，最高分辨率为 0.5 m。该系统的海底原位激发和采集可以完美实现 采集数据的空间一致性，确保时移地震数据反演出水合物开采过程中储层沉积物地震反射特性变化。

Design of Submarine in-Situ High Resolution 2D Time-Shift Seismic Detection System

There is a risk of geological disaster in the large-scale exploitation of submarine hydrate, so it is necessary to monitor the exploitation process. Time-lapse seismic can be used to retrieve the seismic reflection characteristics of reservoir sediments caused by hydrate decomposition. Based on the high-resolution multichannel seismic technology, a two-dimensional time-lapse seismic system is proposed in this paper. The structure design, flow design and key parameters design of the system and its main components are given, and the design process and relevant basis are discussed in detail. The system is mainly composed of deep water sparker, deep water multi-element receiving cable, multi-channel data acquisition system, battery pack and its management system. At the same time, it also includes deep water motor, deep water slip ring and automatic cable arranging device. The maximum excitation energy of the sparker is 1 000 J, and the receiving cable is composed of 16 deep-water hydrophones with pressure resistance of 20 MPa. The gap distance between the hydrophones is 1 m. The received seismic wavelet is processed by the 16 channel acquisition system and stored in situ. The system is powered by lithium battery and adopts the periodic wake-up mode. It is designed to work underwater for 2 months and conduct data acquisition once an hour. The maximum working depth of the system is 1 500 m, the maximum stratum penetration depth is 250 m and the maximum resolution is 0.5 m. The insitu excitation and acquisition of seabed can perfectly achieve the spatial consistency of acquisition data, and ensure that the time-lapse seismic data can reflect the seismic reflection characteristics of reservoir sediments in the process of hydrate mining.