Low relief structure interpretation and mapping of the Donghe Sandstone thin reservoir based on seismic data

Abstract

The Donghe Sandstone reservoir in the Hade Oilfield of the Tarim Basin is characterized by thin layers, great burial depth and large well spacing. The hydrocarbon accumulation is greatly affected by low relief structure. The convex parts of the low relief structure are favorable for the enrichment of oil and gas. Due to wave interference behavior, the top reflection does not correspond to the actual top surface of the thin bed. A few milliseconds of shift in the picked two-way-time horizon generates several to tens of meters depth error. Based on a comprehensive analysis of stratigraphic features and thin bed tuning analysis, a method for time horizon correction is proposed. By extracting the two-way-time of the top reflector from a synthetic seismogram, and subtracting it from that of the real top surface in the models, time offset curves are constructed. By adding the offset value to the interpreted horizon, the time horizon is corrected. After depth conversion, 44 low convex relief elements are identified. Hercynian tectonic movement during the Permian and the superimposed deposition of coastal sand bodies are the main causes of low relief structures. Quality check results show that the mean relative error is approximately 1.5‰, far less than that of previous uncorrected structural map. This work adds value aiding in the characterization and evaluation of the hydrocarbon reservoir. It provides a basis for oil production in the Hade Oilfield and may be potentially applicable to other regions to increase the hydrocarbon production in low relief fields.