Abstract:

 The oil producing interval of braided river delta reservoir of the HZ-A oil field is buried at the depth of more than 3500 m. It is characterized by low frequency seismic data, sparse wells distribution, and big sand-body thickness variation in target zones, which lead to great difficulties in stratigraphic correlation. In this paper, an integrated and practical method of isochronous correlation is put forward. Specific steps are as follows. First, the braided river delta sedimentary characteristics are achieved from the detailed analysis of its provenance and catchment system; Second, based on precise well-to-seismic calibration and fine seismic facies analysis, three-order stratigraphic framework and sub-layer correlation trend are obtained; Based on geophysical inversion, an inversion method for small-scale correlation is proposed to the sub-layer division and contrast; Finally, high resolution sequence stratigraphy theory combined with the correlation of fluid properties, sedimentary micro-facies sequence is applied to logging cycle division from big to small, and the stratigraphic subdivision and sand body correlation of target interval is accomplished. This method can effectively reduce the uncertainty of sub-layer division and contrast. Advantages have been achieved in the application of this method for fine-scale stratigraphic classification and correlation of braided river delta in the HZ-A oilfield.

Key words: sparse well block, braided delta, high resolution geophysical inversion, sequence stratigraphic correlation, HZ-A oilfield, Huizhou depression