Study Of Well Log Data And Characteristics Of Reservoir In Siwujiazi Oil Field

In this paper, for the geological characteristics of reservoirrocks, thin reservoir thickness and difficulties of reservoirunderstanding, the reservoir was study of well log data andcharacteristics of reservoir bed, to establish foundation of thereservoir developing effectively and reasonably, usingsynthetically the theory and methods of stratigraphy, sedimentology,petroleum geology, reservoir geology and petroleuw reservoirengineering and so on.The main content of the research is geological researchassessment, including strta correlation, sedimentarycharacteristics, reservoir lithology, types of reservoir andproperty of fluids, reservoir well log, relationship of the mainfour characteriscs, distinguish of oil and water, reservescalculation and evaluation.The main results of the research:(1) Technique of detail strata correlationBased on the analysis of sequence stratigraphy, the main objectis Yingcheng Formation, depend upon each well's cyclothem,lithology, and electric properties etc. Division of members isbased on lithology and fossil organism, controlled with stabledatum horizon, using correlation methods -"cyclothem correlation,classification controlling". According to datum horizons,Yingcheng Formation is divided into 5 sand sets, 21 sand members. Sand sets are entitled as W1, W2, W3, W4, and W5.(2) Sedimentary microfacies and reservoir evaluationCombinging with predecessors'research results andcore and well log information, the main oil sands wasstudied according to sedimentary microfacies and the typesof microfacies were comfirmed. The relationship betweenwell log electrofacies and microfacies was established.Profiles and ichnograph of the sedimentary microfacies weremapped. And the characteristics of the differentmicrofacies and the distributin of sands were elaborated.Depositional model was set up. Spacial distribution regularpattern of sedimentary environment and microfacies and thehistory of sedimentary evolution were discussed.Based upon the sedimenatry indication study of lithology,electrical properties and granularity, that was divided into 1intrafacies, 5 microfacies, which are underwater braided channel,foliar sand bar,sand sheet (thin sands), mudstone microfacies ofdistributary bay and lake. In which, underwater braided channel isthe main sedimentary microfacies type in Yingcheng Formation.According to the information of sedimentary features,lithology and physical properties, it is thought that thereservoirs of Yingcheng Formatin are reservoirs with low porosityand low permeability, in which sands of members W1-1, W1-2, W1-1,W1-2,W2-3,W4-2,W5-2,W5-3, W5-4 are developed well. The sands aredistributed with splinter form in large area, the thickness andeffective thckness of the sands are thick. The sands are thereservoir rocks of the main force. (3) Identification technique of oil,gas and waterlayersUsing histograms and crossplots to correct the curvesof porosity, well log curves are normalized. A fter studyingof four properties of reservoir, it was thought that thegrade of lithology is fine sand level above, in which theelectricity criterion is that the resistance is greaterthan 36Ωm, acoustic slowness is greater than 220μs/m, oilsaturation is greater than 37.2%. Establishinginterpretation model of well log, the well log data wasprocessed and overall evaluated.(4) Reserves evaluationBased upon the geological judgement, combining with information ofdynamic and static and production test, using unit in verticalmember and plane fault block, the calculated area of oil is 1.75km2,and initial oil in place is 168×104t.Overall evaluation of SN17-SN203 Fault Block is thought as oil field of low porosity, lowpermeability, medium–low abundance and special minitype .Reservoir evaluating of detail blocks and members, in SN205 Block,the main forces are members of W4-2,W5-2,and total reserves is22.46×104t; In SN203 Block, the main force are members of W4-2,W5-3, and total reserves is 33.5×104t; In SN17 Block, the main forceare members of W1-2,W2-3,W5-2,W5-3, and total reserves is 45.32×104t, account for 45.6% of blocks reserves.