The Research And Application Of Acoustic Curve-Reconstructing Techniques In Constrain Inverse

In order to achieve sustainable development for Nanpu oilfield, reservior prediction is indispensable. The Tan-lu and Yanshan faults system form the main construction, so the zone is rich in faults and fragment. Sedimentary filling in the East of Nanpu depression is divided into two parts: Late Tertiary sedimentary model of delta and Early Tertiary sedimentary model of braided river,sedimentary models are controled by fault system,which makes reserviors to vary much laterally. Lithology is classified into glutenite,packsand,siltite,basalt,tuff,mudstond and conglomerate, many rocks are distributed of equal thick and mutually cross. Porosity of sandstone is higher, the maximum can reach 33.5%, the kind of permeability reservior is classified as high or medimum generally. Test showed that gas and oil coexsit, which leads measured density is lower than true density, even lower than the surrounding rock. Drilling showed that mudstond is mixed generally with calcareous and sand, coupled which higher porosity in the region, it is not obvious that acoustic time curve respond to reservior characteristic. The prerequisite for constrained seismic inversion is that the acoustic time answer characteristics of the reservoir and surrounding rock differently, thus, predicting characteristics of reservoir distribution is a core research topic.This paper investigate and research the current status of domestic and international prediction reservoir studies and combining oilfield research situation, and summarizes log-reconstrusting techniques in constrain inverse, which meet the reservoir's requirements .as follows:(1) Logging curve pretreatment: using double standard layer correction method to standardize well logs, after standardizing, logging system response to the region becomes more consistent. Considering different method of density log reconstruction (Gardner model, volume and statistical regression model) in accuracy and stability, multi-parameter regression method is selected as the density log reconstruction method that can meet the expanding hole correction requirement. To replace the original acoustic time outliers with Faust formula to reconstruct.(2) The reconstruction of acoustic curves: first, the process of eliminating low-frequency is on the sonic curves, and analyzing if sonic curves associate with other log, the final selection of natural gamma, resistivity, compensated neutron and density is involved in reconstruction of reservoir characteristics curve, this curve identifies lithology capacity greatly increased, not only has the acoustic characteristics of jet lag, but also the nature of other logs . Reconstruction of synthetic seismic reservoir characteristic curve is higher correlation to the seismic records.(3) Reservoir prediction: in order to control the quality of reservoir characteristics curve inversen reconstruction, carring out error analysis in the measured and predicted impedance of wellheads, and in the predicted wave impedance and the actual synthetic seismic profile of seismic profiles error analysis, also,confirmatory well analysis, not only reflects the inverse results higher match the well point and seismic profiles, and work out a set method of inversse quality control.