Lithologic Trap Prediction Of N₁s^1-2 Formation In Chunguang Block, Junggar Basin

Chunguang block of Chepaizi uplift is located in Northwestern margin ofJunggar Basin, it is a north monoclinic structure. Trap type mainly contains structurelithology, lithology traps. Since2005, found out pai2reservoirs by accident, asbright spot mode for guiding pleasantly surprised to find13similar lithologicreservoirs. After2008, exploration deadlocked.2009Chunguang area was placed byHenan Oilfield Authority, recognizing that the study area reservoir does notnecessarily have a bright spot display, combined with lithologic traps and seismicresponse for exploration, chun2make breakthough and also have some well come tonothing. This fully illustrate in the later exploration, single seismic physical approachis too restrictive, through the intergrated study of petroleum geology,on the basis ofunderstanding of the sands body distribution rules and hydrocarbon accumulation,andcomprehensive analysis of the seismic respose characteristics to predict traps.In response to these problems, the paper mainly learning to sequence stratigraphy,seismic stratigraphy, sedimentology and structural geology theory as a guide, on thebasis of previous research, on the one hand, access to large quantities of oil and gastransporting system and literature of the chepaizi area area,on the other hand, usemore detail well data and3D seismic data, through the fault interpretation, basal（Carboniferous unconformity） structural map, forming a new understanding ofaccumulation of the area; through the compaction curve analysis of the sand and shale,Synthetic Seismic Record, wave analysis of well and seismic data andtwo-dimensional forward modeling, by identifying the seismic responsecharacteristics of target layer (N₁s^1-2), though sand body scanning methods track anddepicts the sand body in the isochronous stratigraphic framework, get the flat maps ofthe purpose layer, combined with the recovery profile of sedimentary basins, analysis depositional system; As seismic response characteristics predict and evaluatefavorable traps on fully aware of the hydrocarbon accumulation and sand distributionlaw.The progress and understanding main include:1) Selection of the transgression-regression model, the Shawan Formation isdivided into three sequence, the sequence boundary consistent with thelithostratigraphic units used in the production; Shawan Formation is divided into foursand group, N₁s^1-1,n1s^1-2, N₁s^1-3N₁s^1-4, local development N₁s^1-2-1;2) Of the Neogeng in the first section of Shawan group, The sandstone speed isless than the mudstone, mainly to the type I sandstone, performance of the trough onthe the negative performance profile. By tracking the trough represents the topinterface of sand sets to describe the skeleton of sand distribution. Some areas thicksand, Type II sandstone requires the use of seismic facies analysis to be identified;3) That during the deposition of period, there are two larger provenance ofnorthwest and north direction, development of two large water system, that is braidedfluvial delta depositional system, lake sedimentary system. Delta depositional systemis mainly composed of the delta plain, delta front and fore-delta; lacustrinedepositional system is mainly composed by the lakeside subfacies and shallowlacustrine;4) Point out that the K/C unconformity is the main channel of the lateralmigration of the chunguang area, and pointed out that the distance to the unconformity,fault to open, and whether in the dominant channel of hydrocarbon migration of thearea are the three major constraints for the reservoir of the traps;5) Identify31lithologic traps in the target layer, and evaluation of the fourfavorable traps.