| Fuling area is located in the syncline of Ba shanshi, east of Sichuan Basin, faces Dachigan gas field on the east, Datianchi gas field on the west, with low degree of exploration, little drilling. Maokou formation’s karst reservoirs space is mainly holes fractures and cave, with characteristics of strong heterogeneity and lateral change. For the complexity and concealment of Fuling area Maokou formation karst reservoirs, this thesis is guided by multidisciplinary, integrated using and all kinds of well logging, seismic technology to recovery karst geomorphology and predict reservoir.This papers is on the basis of stratigraphic classification and correlation and horizon’s calibration explanation; through fine structure description and recovery of karst geomorphology,discussing working area’s structure characteristics of nowadays and Dongwu stage characteristics of karst geomorphology, on the basis of reservoir rock electricity sensitivity and analyzing geophysical response characteristics, utilizing seismic attribute to definite anomaly seismic distribution, using seismic inversion technique to predict reservoir thickness, and all kinds of fracture prediction technology can be used to determine the fracture development zone, through the detection technology of oil and gas to find relatively hydrocarbon block. Eventually,forming a system of identification and prediction that aimed at syncline karst reservoir with geological and geophysical method, the mainly results and understanding are as following:(1) The studying area as a whole is a broad syncline, distributes from northeast to southwest, with high relief. The string along bxl-xl2well is the maximum area of tectonic cover depth, taking this area as a center, along the northwest and southeast, construction turn steep rapidly, contour dense and burial depth shoaling. There are few faults in the studying area, mainly in the southern edge, while in the north and northwest area develop northeast-trending reverse fault.(2) Uniting seismic and drilling closely, combined with geological characteristics of the studying area and actual data situation,considering that impression method is more suitable and reliable than the residual thickness method for karst palaeogeomorphology recovery of the studying area Maokou formation. Maokou formation can be divided into three kinds of secondary karst geomorphology unit: karst platform, karst gentle slope and karst steep slope, karst platform is located in the central of studying area, distributes from northwest to southeast, karst gentle slope position is in the northeast, karst steep slopes are located in southwest.(3) By the analysis of reservoir rock electricity sensitivity of Fuling area, considering that Maokou formation reservoir with characteristics that high acoustic travel time, low GR, high density, middle-high resistivity, there exist certain diameter extension phenomenon. Using geological and geophysical method to analysis Maokou formation reservoir’s seismic response characteristics, they can be classified into three categories, Ⅰ:strong wave and strong peak, strong peak corresponding to the reservoir; Ⅱ:sinuation and minor axis reflection, Ⅲ:low frequency and weak amplitude on the top of Maokou formaiton.(4) Extracting and analyzing seismic attribute. In the faults zone and northeast area which is nearby karst gentle slope and faults zone, denudation is intense, fracture develops well, and easy to communicate karst fracture, it is anomaly seismic area of Maokou formation top reservoir. While the whole Maokou formation anomaly seismic is located in central karst platform, with smooth landform、small hydraulic gradient and the main karstification means is slow speed diffusion flow dissolution, it can form profitable denudation pores, meanwhile, underground river also develops in the area.(5) logging curve intersection display GR curve is a lithology sensitive curve, acoustic curve can not effectively distinguish argillaceous rocks and reservoir acoustic."modulation" into pseudo acoustic curves with acoustic curve, developing proposed acoustic lithology inversion. By the threshold value, filter out mud on the wave impedance inversion profile, picking up the reservoir. The thick reservoir mainly develops in karst plateau area of fsl-bx2well block, distributes from northwest to southeast, southwest area steep slopes also develops karst reservoirs, but thinner than the karst platform. Due to stratigraphic repetition, near the revese fault, reservoir thickness significantly increases.(6) Applying coherent detection, discontinuity edge detection and stress field simulation method into fracture detection. Coherent detection can detect fracture and fracture with cracks, in addition to fracture and fracture with cracks effectively, discontinuous detection can detect micro crack to some extent. Stress field simulation is mainly used to predict the structural joints. For Maokou formation, the micro-cracks are very important for the communication with syncline area karst fracture reservoir. The discontinuity edge detection is higher reliability in the three fracture prediction methods. For the entire Maokou formation, the micro-cracks is development advantages on the gentle slope in the northeast and sporadic development on the karst plateau in the central and on the steep slope in the southwest.(7) Using frequency attenuation attribute and low frequency increment attribute to carry out the study of oil and gas detection. By comparison, high frequency attenuation attribute considered better, gas reservoir mainly concentrated in the northeast karst gentle slope with good shape. Secondly, gas reservoir developed fs1-bx1well block karst platform and karst steep slopes that near karst platform. Also gas reservoir developed nearby the fault zone.(8) Comprehensively considering various factors, combining reservoir、fracture and hydrocarbon bearing to evaluate using information fusion technology. Divided Fuling syncline area Maokou formation into three favorable zones, including one class Ⅰ, is located in the central part of the karst platform; two class Ⅱ, located in the northeast feng9well area and southwest of bx1well area. |
PDF Full Text Request