Qualitative characterization of sandbody connectivity for meandering river composite channel sandbody at seismic scale with large well spacing

Abstract

Studying the static connectivity of reservoir is essential to predict the lateral connectivity of sandbodies and devise field development strategies. Critical elements of static connectivity include geometry, stacking pattern, and the distribution of sandstone bodies. The meandering river reservoir in the lower member of the Minghuazhen (Nm) Formation is intersected and superimposed by multi-stage channel sandbody, resulting in a complex sandbody architecture. However, in the early phase of oilfield development with limited well data and sparse well spacing, there is a lack of comprehensive characterization of the strongly heterogeneous distribution pattern of channel sandbody and an incomplete understanding of sandbody connectivity, which complicates the optimization of well placement. We conducts a precise analysis of sandbody connectivity at different levels in seismic scale for Lm733 sandbody of the V oil group in the lower section of the Nm Formation, based on a comprehensive utilization of geological data in oilfield and guided by sequence stratigraphy and seismic sedimentology applying stratigraphic proportional slicing and sandbody edge detection technique. The results indicate that Lm733 sandbody can be classified into two composite channel sandbodies, respectively distributed in the early sequence (SQ1) and late sequence (SQ2). Based on the diverse seismic reflection characteristics, varying thicknesses, and plane distribution features of the interbed, the connectivity between two composite channel sandbodies for SQ1 and SQ2 could be classified into three categories (Type-Ⅰ, Ⅱ, and Ⅲ). According to the seismic attribute variation, including amplitude, waveform, and frequency at the internal boundaries of composite sandbodies, the internal connectivity of composite sandbody in SQ2 can be classified into three categories (Type-1,2, and 3), in conjunction with the existing injection-production well pattern. In this manner, predicting the characterization of sandbody connectivity at various levels in composite channel sandbody at seismic scale can aid in adjusting oilfield development plans.