Characteristics Of Reservoir And Fluid Identification Of Tight Gas

Clastic reservoirs of the 2nd Section, XuJiahe formation, the Upper Triassic of Weidong area is one of the important beddings of exploration activity and will be the beneficial layers in future. So it is specially significant in depth study the reservoir characterization and fluid property.This article as a guide to the theory and means of sedimentology, reservoir geology and logging geology and so on, we divided sedimentary facies of 2nd Member of XuJiahe Formation first, and elaborately classified the depositional microfacies; Based on the petrology feature and analysis of physical property 2nd Member of XuJiahe Formation, summed up master control factors of reservoirs and establish grade scale of reservoirs, we expounded spatial and temporal distribution and mass'variation regularity; As a precondition to the response characteristic of logging, we established reservoirs'geologic model with forward and inverse analysis methods; Adopted the way to prestack fractures forecasted based and supplemented by poststack fractures forecasted, we expounded distribution of fractures; As a means to technique of AVO fluid identification, we combined analysis of seismic attribution to build AVO forward analysis methods, and proceeded dependable analysis about fluid forecast. The main achievement of this treatise were as follows:1. Based on delicate description of well drilling core and multidisciplinary analysis of bore log, according to sign of facies about lithologic characteristic, sedimentary structure, palaeontologic typicality, size characteristic and so on, we combined research harvest of predecessors, divided it into the microfacies of underwater distributary channel, mouth bar, distal bar, bay between branches, beach bar, mud between bar, shallow lake bar, shallow lake mud and so on, on 2nd Member of XuJiahe Formation, the Upper Triassic of Weidong area; Proceed comparison and reseach about sedimentary facies of well tie, analyse characteristics of vertical and horizontal distribution about sedimentary facies on 2nd Member of XuJiahe Formation; Finally it indicated that beach bar and shallow lake bar is the beneficial sedimentary facies belt in this area.2. Reservoirs of 2nd Member of Xujiahe Formation mainly is feldspar lithic sandstone, lithic arkose, accessory is feldspar quartz sandstone and lithic quartz sandstone, it is a suite of reservoirs with low porosity and permeability; it mainly grows residual intergranular pores, intergranular dissolved pores, intragranular dissolved pores, microfracture; it has pore structure characteristics about fine pore, middle throat, middle size, nice connect; According to diagenetic feature and multidisciplinary analysis about divided sign of diagenetic stage, 2nd Member of XuJiahe Formation is mainly in Late diagenesis, strong corrosion of feldspar and detritus play an important role on the reservoir development. In controlling factors of reservoir development, sedimentation is the base, diagenesis is the key, tectonization is the important condition about high production of reservoirs.3. Based on the Discussed in detail about reservoirs feature, we combined reservoirs clascification criteria and criterion in region of interest bottom of Reservoir physical property which is porosity 6% on XuJiahe Formation, ShuNan Gas Field, and then proceeded Reservoir Classification by synthesized parameter characteristics of pore structure. The reservoirs divided into four categorys, andâ…¡~â…¢as the main reservoirs in region of interest.4. Used datum of bore log, we proceed Fine calibration of beneficial sandstone, we established reservoirs'geologic model with forward and inverse analysis methods of 2nd Member of XuJiahe Formation, and progressed dependable analysis of model; The result indicated that it is bad about reservoir connectedness of vertical and horizontal direction and it was isolated beach and bar-shaped distribution. Utilized coherence technique, as luff analysis, VVA,AVA, FVA and so on, combining observation of Core split and response characteristics of logging split, we forecasted and evaluatedfracture zone; The results showed that the upper crack of 2nd Member of XuJiahe Formation distribution mainly distributed the southeast of Work area, central crack was mainly on the southeast and northwest, and lower crack was mainly on the northwest of work area.5. We taked the Method of fluid replacement to proceed AVO forward modeling for bed of interest, combined seismic data, researched AVO attributive character, established Abnormal response model of fluid AVO, and proceeded feasibility analysis of model; From the research we found that the beneficial gaseous section of reservoirs mainly distributed in west of Weidong 2well and east of Guanyintang hall, the belt around YuQingsi-Weidong 7well-Zhenzichang field; The big value area of air voids was mainly in west of Weidong 2well, east of Guanyintang, the belt around west of Weidong 8well and YuQing temple-Weidong 7 well- Guanyintang field.Yue101-X12 well have obtained hugely success,was drilled in the fracture zone and favorable place for gaseous section. It is proved that fracture forecasted and AVO fluid identification is very reliability.