The Geological And Geophysical Comprehensive Research Of Gas Reservoir PY35-2in Shelf Slope-break Zone Of The Eastern Pearl River Mouth Basin

PY35-2locates at slope break from PANYU-LIUHUA gas area of eastern pearlriver mouth basin to deep water area of southern BAIYUN depression. The upper partof the lower member of ZHUJIANG formation, the mainly target strata, covered byhuge thick shallow sea shelf mud, is low-stand wage deposition at shelf edge delta andis cut by different geologic period faults. Therefore, the formation is of goodreservoir-cap combination condition. In the end of2007, Shenzhen Branch ofCNOOC drilled at the principal portion of PY35-2trap based on research results. Bydrilling, good quality and thick gas layer is found in the upper part of the lowermember of ZHUJIANG formation, which prove PY35-2and shelf slope break regionare of good prospect.Because of unique sedimentary environment, shelf slope break region is oftendistorted in time domain and researchers are puzzled. Taking a wide view of thedomestic and foreign researches, though rich achievements have gotten, research onshelf slope break region is still very difficult and is a worldwide leading edgeproblem.Drilling results of PY35-2make us aware of its complexity and face many severechallenges when evaluate gas reservoir deeply such as structure, deposition, and AVOattributes etc. There are many traps like PY35-2in shelf slope break region, northslope of BAIYUN depression, eastern pearl river mouth basin. Deeply geological andgeophysical integrate research on structure, deposition, and AVO attributes of PY35-2is not only deepen our understanding of this gas reservoir, but also guide us toevaluate other similar gas reservoirs in shelf slope break region, north slope ofBAIYUN depression, eastern pearl river mouth basin.This study have the following breakthrough:①combining well and seismic,applying principle of seismic sedimentology, integrating research on controllingaction to sedimentary sequence development and evolution from paleo tectonic, sealevel change and sediment dispersion system, sedimentary attribute of PY35-2gas reservoir is determined.②In view of low resolution of seismic data, post-stackHFE frequency-extending and AIW impedance inversion are adopted to determinesedimentary attribute edges of PY35-2gas reservoir. Combined result of pre-stackdepth migration processing, depth structure attribute is given.③combining well andseismic, making pre-stake AVO three attributes（ρ、κ、μ） inversion to get AVOthree attributes’ character and their planar change.④integrating sedimentary attribute,structure attribute, and AVO three attributes to determine bound of gas of PY35-2gasreservoir.⑤A series of geological and geophysical techniques aiming at shelf slopebreak region, north slope of BAIYUN depression, eastern pearl river mouth basin areshaped, that is, sedimentary�'structure�'AVO�'integrating evaluation.Geological and geophysical integrating research is an important direction. Basedon geological and geophysical integrating research on PY35-2gas reservoir, shelfslope break region, eastern pearl river mouth basin, a clear route is given. However,its application in different fields and different areas need to be studied andconsummated more deeply.