Onshore MPD system enables lower mud weights for challenging wells

摘要

In the development of onshore gas fields, Shell has encountered mar gins in which the difference betweendynamic equivalent circulating density(ECD) and static bottomhole pressure(BHP) is the difference between lost cir-culation and influx. The limits imposedby those conflicting conditions createnarrow mud weight windows.The reasons for the tight pore pres-sure and fracture gradient windows inthese vertical and horizontal onshorehigh-pressure, high-temperature (HPHT)tight gas environments vary. Some areold fields challenged by depletion. In thecase of South Texas, the main problemis losses in the production hole due todepletion.