Layer Pressure Research On Fu Ⅲ Member Of Zhang Jiaduo Oilfield

Abnormal high pressure，which has a close relationship with hydrocarbongeneration, migration and aggregation，is a common phenomenon in petroliferousbasins. Zhang jiaduo oilfield as a favorable areas of hydrocarbon migration is locatedin the southeast of Subei Basin, in the west of the haian depression, in the northeaststeep slope of the qutang subsidiary depression and in downthrown side of Zhangjiaduo fault. Prophase exploration and development demonstrate that the mainreservoir for Fu Ⅲ Member,which is tectonic height and under abnormal highpressure, is conducive to hydrocarbon accumulation. However, Dainan，which is thefault development zones and Under normal pressure, is also a favorable hydrocarbonaccumulation zone. So there is close relationship between abnormal pressure andhydrocarbon accumulation. Through the use of seismic date, drilling date, loggingdate, geochemical date and so on, we analysis oil&gas geological features to Fu ⅢMember as the main layer, which is include hydrocarbon source rock, reservoirproperties, and the source-reservoir-seal assemblages. Combined with results ofprevious studies, we determine abnormal high pressure formation mechanism and findthat undercompaction is formation mechanism as abnormal high pore pressure in thiszone. On this basis, we respectively research the mechanism of undercompaction, thecharacteristics of mudstone undercompaction, remaining pressure calculation,establish undercompaction profile and earthquake prediction the distribution offormation pressure. Finally, combined with pressure sealed box and the relationshipbetween undercompaction and hydrocarbon accumulation, we predict a favorable ofoil&gas rich region.Through drill core observation, logging data, seismic data and particle sizeanalysis, Fu Ⅲ Member of Zhang jiaduo oilfield is considered that it is shallow lakesubfacies. Dam sand is its main reservoir and beach sand is minor reservoir. Fu II Member is the main source rocks for the area. When Sanduo formation deposited, itbecomes maturity. Combined with fluid inclusion study, we consider that Fu ⅢMember reservoir have two fillings. We also find that Sedimentary facies types,diagenesis and reservoir properties determine the reservoir performance, that Fu ⅢMember reservoir lithology is fine siltstone and that argillaceous laminae andbioturbation plays an important role. Thin-layer sandstone, thick-layer mudstone,abnormal high pressure determined high grade Fu Ⅲ Member traps. In summary, oil&gas geological features perform well.Abnormal high pressure formation mechanism research helps to predict theexcess pressure distribution, and achieve the safe and reasonable oil&gasdevelopment.At the same time, it is helpful to predict hydrocarbon migration,accumulation and distribution, and finally find new oil&gas reservoirs. Through theregional geological setting and test data, Funing group of abnormal high pressure iscaused by undercompaction mechanism and form earlier. Fu Ⅲ Member reservoirunder deep burial circumstances have good reservoir properties because of thepresence of undercompaction. Through extracting pure mudstone interval transit time,we conduct mudstone undercompaction study. Then, we use the Eaton method tocalculate excess pressure, and establish of undercompaction profile. Before drillingformation pressure prediction are often based on seismic data abundance. The use ofseismic inversion data, extracting mudstone layer velocity and the method of Eatoncarry on pressure coefficients calculate help us to obtain layer pressure planedistribution.In the formation and evolution process of abnormal high pressure, pressurecompartment plays an important role in hydrocarbon accumulation, which protects thereservoir pore, and aslo controls the distribution of oil&gas. According to reservoircharacteristics, the region is divided into two types, namely hydrocarbonaccumulation inside pressure compartment and hydrocarbon accumulation outsidepressure compartment. hydrocarbon accumulation inside pressure compartmentconserve oil&gas is caused by excess pressure and lithology seal. hydrocarbonaccumulation outside pressure compartment is caused by the action of fault or crack.It refers that hydrocarbon migrates out of the high-pressure compartment andultimately accumulates in normal pressure reservoir. In this study, we consider that FuⅢ Member hydrocarbon accumulation is hydrocarbon accumulation inside pressurecompartment and Dainan Formation is hydrocarbon accumulation outside pressurecompartment. In the favorable exploration forecast, bar sand deposition and the excess pressure distribution should be key point to hydrocarbon accumulation insidepressure compartment. However, to hydrocarbon accumulation outside pressurecompartment, predicting the favorable exploration zone is based on fault analysis as aguide,which is combined with the overlying connected sand body.