Effect of Stratigraphic features on Deep-Water Cementing Operation - A Review

Abstract

Drilling operations in deep-water environment is faced with technical challenges despite its massive record of huge hydrocarbon reserves when compared with onshore oil and gas fields. The weak, unstable formations coupled with adverse deep-water conditions poses as a challenge to cementing operations. Narrow pressure window conditions are encountered when the wellbore pressure required to contain subsurface pressures lies close to the pressure at which losses may be sustained. This is evidence in the ratio of pore pressure to vertical stress moving close to lithostatic condition. This can either be caused by porous formation or by the way of inducted fractures in weak or sheared or unconsolidated zones in the subsurface. This study showed an overview of some possible challenges faced in deep-water cementing operations in relation with stratigraphic features of the deep-water environment. From the review it was gathered that the stratigraphic nature of deep-water environment has a huge effect on cementing operations for oil and gas wells. The study also highlighted some gaps in the literature which require urgent attention to reduce loss circulation. These gaps include but not limited to: spacers generating sufficient downhole force to overcome the yield stress of the mud and the need for a new type of treatment for lost returns. Managed pressure cementing operations may control wellbore pressures.