JOINT INVERSION OF MPR AND HDIL MEASUREMENTS

摘要

Traditionally, measurement-while-drilling (MWD) data are used primarily for geosteering purposes and drilling decisions such as monitoring of hole direction, deviation, and delineation of abnormally pressured zones. Wireline resistivity measurements, galvanic and induction, play a fundamental role in identifying and delineating oil- and gas-bearing formations. In recent years, MWD logs have been used not only for drilling decisions but also for real-time formation evaluation. The availability of both MWD and wireline data not only provides the interpreter with abundant information about subsurface formations but also poses a new challenge to generate a unique model(s) that better explains both data sets. In this study, we combine MWD and wireline measurements in order to take advantage of the best features of the data in finding a consistent earth model. The proposed interpretation is applied to synthetic and field data examples.rnMWD and wireline data obtain responses from similar subsurface formations at different times, reflecting different borehole and invasion conditions. Each of these data offers distinct advantages when compared to the other. In general, MWD data are not affected by invasion, allowing better interpretation of formation resistivities. On the other hand, wireline data allow us to characterize the invasion profile, resulting in identification of permeable and impermeable zones, and thereby facilitating the evaluation of movable and residual hydrocarbons.rnConventionally, MWD and wireline data are interpreted independently to estimate formation resistivities that might result in inconsistent earth models. In our study, a dual earth model that describes the appropriate logging conditions of both wireline and MWD is considered. This model contains a set of common parameters including the true formation resistivity and bed boundaries. An inversion process that handles the dual model has been developed and implemented that deals with any combination of wireline and MWD resistivity measurements. The proposed scheme is implemented using Multiple Propagation Resistivity (MPR~(SM)) and High-Definition Induction Log (HDIL~(SM))rnmeasurements. The value of the joint inversion process is demonstrated by the estimation of reliable and consistent formation parameters for both synthetic and field data examples.