Seismic-Based Volcano Identification and Characterization in HD Oilfield, Tarim Basin

Abstract

HD Oilfield is located in the center of Tarim Basin, China. As the target of this study, the Carboniferous Donghe sandstone is characterized by middle porosity, middle permeability, high structure maturity and few interlayers. The practical hydrocarbon development of the recent twenty years shows the spatial heterogeneity of the marine Donghe sandstone. This phenomenon is hardly explained just using interlayers. Aiming at the cause of reservoir heterogeneity, we take a specified study on the seismic processing and interpreting process. In this way, a series of small ancient volcanic zones are discovered for the first time in this oilfield. These volcanic zones are very beneficial for secondary development. Our study also brings a new solution for the further study on the non-penetrated zone within the reservoirs. In order to characterize the main target stratum, the processing technique that both enhances the vertical resolution and relatively preserves the information of the reservoir is applied. The relative amplitude preservation processing technique mainly includes earth absorption compensation, and two-step deconvolution based on shot-receiver gathers. The major processing steps have been monitored using the geophysical and geological QC method during data processing. Based on the high-precision processing results, seismic attributes such as variance, curvature, ant colony and edge detection cubes are extracted. And integrating them with 3D visualization techniques, comprehensive study on the volcano distribution was conducted. Through integrated analysis of seismic attributes, geological data and drilling results, we conclude that hundreds of volcanos are widely developed in this zone and mainly distributed from south to north with a belt shape. There are two major volcano development zones in the Donghe sandstone, namely the east zone and west hydrocarbon bearing zone, respectively. Volcanic conduit diameter in the east zone ranges from 600 meters to 1000 meters, while the diameter in the west zone is smaller and ranges from 10 meters to 80 meters. As seepage flow barriers, these volcanos locally control the spatial distributions of reservoirs.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015