Study On Remaining Oil In Fracture-vuggy Carbonate Reservoirs Of Tahe Oilfield6-7District

In this thesis, on the basic of considering the geological Present Situation anddevelopment characteristics in the Tahe6-7Ordovician carbonate rocks reservoir, byusing the information of geological, seismic, well logging, reservoir engineeringresearch methods, the author carry out research on the remaining oil distribution andits control factors inTahe6-7District.First of all,3D reservoir geological model is established according to types ofsingle-well reservoir, at the same time the model is controlled with seismic data.Secondly analyze the inter-well connectivity and connectivity pattern on the basics ofthe model. And analyze the factors which influenced single well water change.Ultimately, get distribution pattern of the remaining oil and predict its distributionarea. The author achieves the following conclusions:(1)Deepen the understanding of the distribution of vuggy reservoir body.Established the classification standards of reservoir types such as unfilled cave,sandfilled cave, collapsed material filled cave, dissolution fracture and pores inlogging response of Tahe6-7District with logging and production data.And the reservoir type of all wells are confirmed. Statistics show that thereservoir become bad from top to bottom, and the cave reservoir mainly developed inthe middle and lower segments while the dissolution fracture reservoir developedwidely.(2)There are two stable densification regions in Tahe6-7District. Confirme thedensification region of85wells with the standard of logging response. With theconstraints of seismic data the author gets the thickness map of the two densificationregions. The Z1thickness is well-distributed and relatively continuous, with theaverage thickness of13.97m. The Z2thickness has a poor continuity distribution andhyperdispersion, local thickness is large to70m, and the average thickness is13.45m.(3)Tahe6-7district reservoir production capacity from good to bad with thefollowing order: unfilled cave, collapsed material filled cave, dissolution fracture,sandfilled cave and dissolution pores.(4)The inter-well connectivity and connectivity mode is researched. The studyfound that in overall6-7district the connectivity is banded structure in the NE, whichis same as the direction of the major fault. The author summarizes three kinds of wellconnected mode, and the actual well connectivity mode can be seen as a combinationof basic connectivity patterns. Studies show that fracture reservoir injected with cavereservoir produced and low position reservoir injected with high position reservoirproduced is in favour of flood development. (5)3D reservoir geological model is built in the mainly unit of the6-7district.On the basis of densification region study, the densification region and unit reservoir3D models of S67, S74, T615and T444are built, which using the single wellreservoir classification standards, and the characteristics of production and as wellas a variety of seismic attribute constraints.(6)Come up with new production dynamic curve. The slope of cumulative oilproduction to total liquid production curve reflects the oil productivity of single well.The slope of cumulative water production to total liquid production the curve reflectsthe water ratio of single well.The differentials of cumulative oil production and cumulative water production tototal liquid production slope of the curve reflects the oil and water production processvariation of wells. The single well’s water-ratio trends are classified as slow rise, fastrise and storm flooding on the basis of the new production dynamic curve.(7)The flooding situation of the Tahe6-7District is controlled by resevoir type,the thickness of densification region, deep faults and well group connectivity mode.(8)Summarized six kinds of distribution pattern of remaining oil: unused,low-amplitude unaka controlled，the densification region barriered, closed endpointcontrolled, attic dominated and storaged in dissolved fracture and pores around highpermeability region.(9) The author make the remaining oil distribution of four main units in Tahe6-7District clear.68bodys of unused remaining oil exist in C1segment while69bodysexist in C2segment.25bodys of low-amplitude unaka controlled remaining oil existin C1segment.23bodys of the densification region barriered remaining oil exist inC2segment.7bodys of closed endpoint controlled remaining oil exist in C1segmentwhile3bodys exist in C2segment.20bodys of attic dominated remaining oil exist inC1segment.15bodys of remaining oil that storaged in dissolved fracture and poresaround high permeability region exist in C1segment while14bodys exist in C2segment.