Gravel Placement in Wells

Distinguished Author Series articles are general, descriptive representations that summarize the state of the art in an area of technology by describing recent developments for readers who are not specialists in the topics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and present specific details only to illustrate the technology. Purpose: to inform the general readership of recent advances in various areas of petroleum engineering. Summary Several gravel-placement techniques are available to the engineer for prepacking and gravel packing wells where sand control is required. Both water and viscous fluids have been used effectively to prepack gravel outside the perforations; however, when gravel packing the annulus, the advantages and disadvantages of each fluid become more apparent. Research and field experience has shown that water is a more general-purpose transport fluid for gravel packing than are viscous fluids. The latter are best suited for low well deviations and relatively short completion intervals. Introduction Gravel packing wells has proven to be a viable completion technique to exclude formation sand from produced fluids. The state-of-the-art has steadily improved during the past few years to the point that in certain oil and gas producing regions, the majority of the wells are gravel packed. Gravel packing involves the placement of accurately-sized gravel packing involves the placement of accurately-sized gravel around a screen or slotted liner in a well to form a downhole filter that will prevent the entry of formation sand into the well, yet allow the flow of formation fluids. Gravel packs can be performed either in open-hole intervals or inside perforated casing (cased-hole gravelpacks), but the usual choice is the latter. The primary reason for this selection is that fewer complications are encountered with drilling and completion operations. However, there are also reservoir and workover considerations Open-hole gravel packs are selected when drilling, completion, and reservoir conditions are ideal. Since such conditions seldom prevail, cased-hole gravel packs have been the usual choice.