APPLICATIONS OF TIME LAPSE LWD TO IMPROVE PETROPHYSICAL INTERPRETATIONS AND DRIVE OPERATIONAL EFFICIENCIES

摘要

The Shah Deniz field is a giant, high pressure, gascondensatefield located about 100km offshore inthe South Caspian Sea, Azerbaijan. The fieldconsists of multiple stacked, clastic reservoirs withlarge contrasts in pore pressure between somereservoirs. There is a very narrow drilling windowand reservoirs are drilled with high overbalance.Sensitive shales make borehole conditionschallenging for logging. In addition, clay-richsands, variable invasion and thin beds complicatelog interpretation. High quality, targeted dataacquisition is therefore essential.Because of the drilling conditions, Logging WhileDrilling (LWD) has become the most commonmethod of acquiring petrophysical data. A majoradvantage of LWD is that the tools continuouslyacquire data. It is thus possible to acquire time lapsedata, either as part of a plan, or opportunisticallyduring normal drilling activities. These data aretypically cost-effective and low-risk to acquire, buthave high value, both for short term operations andfor long term reservoir description. This papershows several examples of how LWD time lapselogs have added value on Shah Deniz. The paperwill show how they can contribute to long termreservoir management by refining perforationselections and improving porosity estimates. Theyare equally useful for diagnosing operations issues,for example by identifying loss zones, investigatingwellbore enlargement and creating pseudo calipersfor cementing calculations.The paper will demonstrate that the total valuewhich can be delivered from time lapse LWD farexceeds that derived from as-drilled data alone.