P₁h³+2 Gas Reservoir Description In The Southwest Margin Of Daniudi Gasfield, Ordos Basin

Daniudi gas field located in northeast of Ordos Basin, and He3+2 member is the main productive pay zone in this field. Analysis and study of characteristics of gas reservoirs could provide reliable evidence for the future exploitation of this gas field. This paper aimed at the characteristics of Daniudi gas field, and studied by selecting He3+2 members as the target area. Based on exploration data, controlled the tectonic and stratigraphic features with target area. We divided He3+2 reservoirs on the basis principles of sequence stratigraphy. Judged sedimentary facies indicators by cores and well log data, and then described sedimentary facies from the plane and three-dimensional on the whole region. We found out overall situation of reservoir and critical value of each parameter from parameter value and distribution. Finally based on tectonic, sedimentary and reservoir characteristics, and combined with production and test data, we described the distribution of gas pool in the region.To use gas reservoir description technology, combined with previous research experience we made the following conclusions through relating 203 develop wells and 20 exploration wells'data. He3+2 members overall structure flat, with local micro-uplift. We divided the target reservoir into 5 subzones through comparison of sedimentary cycles. The main facie is meandering river in region of interest, and the most developed channel sand is in H3-1 subzone. He 3+2 reservoir types are low porosity and permeability, its porosity values found in 3%-6%, and permeability values found in 0.1×10-3μm~2-0.8×10-3μm~2, and He3-1 subzone is the best. According to mercury penetration and relative permeability data to determine the lower limit of reservoir properties respectively. Throat radius lower limit is 0.05μm, porosity lower limit is 3.9%, and permeability lower limit is 0.1×10-3μm~2. Reservoir heterogeneity is strong, and each parameters more than strong uniform standards, porosity and permeability between horizontal and vertical distribution of large. high capacity wells mainly in the lower He3 in the region, develop wells which QAOF is more than 10×104m3/d about 25%, and the distribution of gas productive reservoir is severely affected by heterogeneity.