Research On The Reservoir Characteristics Of The Yageliemu Formation In Yakela Gasfield

Since1984when there are high gas and oil production in Shacan2, the oil andgas production has been a great breakthrough through previous research andrecognition. However, for Yageliemu formation the recognition on the internalstructure is low, the sand distribution is not clear, the relationship between gas andwater is complex, the usage degree in reserves is low and the heterogeneity is serious.With the in-depth development, for increasing the production, adjusting thedevelopment program and preparing for the sequent numerical simulation on the gaspool of Yageliemu Formation, it is classified the sub layer, studied the sedimentary,interpreted the reservoir parameters, identified the fluid, researched on the geologicalmodeling and heterogeneity and finally evaluated the reservoir types under the guideof theory and methods of high-resolution sequence stratigraphy, sedimentology,logging geology, reservoir description., on the bases of geological characteristic, coredata, logging data, seismic data and test data.The main lithology is fine feldspathic lithic sandstone in Yageliemu formationand pore type is intergranular. The range of tested core porosity is between1.7%²1.2%, which belong to middle-low porosity. The range of permeability isbetween0.05and611.31×10^-3μm², with middle^low permeability characteristics.Using high resolution sequence stratigraphy, after identification on short,medium and long-term cyclic sequence boundary in Yageliemu formation, the targetlayer is divided into a long-term, three medium and nine short-term cyclic sequence.On this basis, it is carried on division and correlation of sub-layer and sand bodycharacteristics of vertical and horizontal distribution. It is acknowledged that thehorizontal connectivity of the upper sandbody is better than the lower in Yageliemuformation,the upper and lower segments and the lower house have a separate role compartments,MSC3cycle of small layer of sand developed best.Through studying the sign of sedimentary facies, logging facies and seismicproperties of the phase in the area, the vertical and planar distribution characteristicsof sedimentary facies were determined.It is acknowledged that the lower member ofYageliemu formation developed braided channel and pan film deposition of alluvialfan of middle-fan; the upper member developed underwater distributary channel ofbraided delta front at the edge in the primary structure area and braided channe ofbraided delta plain developed at the north and northeast.After the study of four characters, core scale logging, core homing,standardization and normalization of logging, it is established neural networkinterpretation model for porosity and permeability. The absolute error of porosity wasless than1%and the relative error of permeability is between10%⁴0%, which meetsthe accuracy for modeling.Using experience statistics and the relative permeability method, we determinedthe lower limit of reservoir properties in target layer. Using the plate method, multiplediscriminant and neural network method, it is carried out fluid identification to126reservoir segment. After comprehensive analysis, it is indentified80gas layers,9gaslayers and water and37water layers, and determined the gas-water interface to be in-4380.5meters.It is divided the study area into main area and C4well area and constructedmodeling separately based on the results of previous explanation. It is created porosity,permeability and water saturation properties models, with restricted conditions in thesedimentary facie using variogram analysis method. After coarsening of thegeological model, the calculated total geological reserves was257.72×108m3.Based on the casting, pressure mercury data, results of stratigraphic sequenceand log interpretation, it is evaluated micro, plane, interlayer and layer heterogeneityfrom the size, distribution, connectivity of pore and throat, sandbody geometry form,physical distribution, heterogeneity parameters, distribution of compartment andmezzanine. Using weight evaluation method to classify the reservoir, which can bedivided into three categories, of which44belong to classⅠ,45are typeⅡ and37are type Ⅲ reservoir. Meanwhile, it is established classification standards ofreservoir and summarized reservoir characteristics of various types.