Study On Evaluation Of The Reservoir Sai-83-block Of Erlian Basin At Early Time

Sai-83-Block lies in the Zhabu Structure zone Saihantala Depression Sag of Erlian Basin,in which the Sai-83X-well that is in the middle structure was found.As an inclined well ,Sai-83X well has six oil layers(39m in total),one poor oil layer(3m in total) from log interpretation and its daily oil production is 16.8 m3 after the fracture and blowing off.After the production test in August 2006,the daily oil production is always above 3t and the cumulative oil production is 3600t. The oil reserves forecasting is 786*104t.We have carried out study on early reservoir evalution,such as stratigraphic correlation,3D structure-interpreting,sedimentary facies analysis,reservoir prediction and map out five appraisal wells.The main oil source layers which include three groups and five formations in Saihantala Depression are in the Mesozoic Cretaceous Bayanhua Group.From top to bottom they are Saihantala group,Tenggeer group(divided into Tengyi Formation and Tenger Formation),Saihantala group(divided into a4 Formation and a3 Formation).The major oil producing zone in Sai-83X-Block is Tengyi Formation,whose oil layer’s top which is a NNE trending nose structure overlapped above the eastern slope zone is very simple.The middle reservoir is buried about 1750m. Faults don’t develop in the fault-block.The lithologies of the reservoir are fine sandstone and calcareous sandstone. The sources of sediments are from the eastern slope zone.The sedimentary evironment is fan delta front submersed channel,which has near-sourses,narrow faces and rapid faces etc sedimentary features.The oil reservoir which is controlled by both structure and reservoir is a structural-lithological reservoir.The five appraisal wells distribute all over the fault-block.The longest distance between the appraisal well and Sai-83X-well is 1000m and the least diatance is only 400m.The thicknesses of reservoir are thin in comparison with Sai-83X-well.Three of them are without casing because of undeveloped reservoir.All of these indicate that the Sai-83X-well lies in the main source direction,so its thickness of sand body is the biggest and the lateral pinchout is fast. The fault-block reservoir scale is small and the oil reservoir is about 137*104t.We should construct while rolling in the area whose reservoir scale is small and thickness horizontal variance direct is fast.We will prove reserves with new deliverability and decrease the investment risk .