Gravel sizing method for sand control packing in hydrate production test wells

To deal with sand production problems during the process of producing natural gas from hydrate-bearing sediments (HBS) using reservoir-fluid extraction method, a new gravel sizing method for sand control packing named “Hold coarse while eliminate fine particle (HC & EF method)” was developed for the clayey hydrate-bearing formations. Site X, in Shenhu area, South China Sea was taken as an example to describe detailed gravel sizing procedure. On the basis of analyzing basic particle size distribution (PSD) characteristics of HBS at Site X, the formation sand was divided into two components, which are coarse component and fine component. The gravel sizes for retaining coarse component and eliminate fine component were calculated, respectively. Finally, intersection of these two gravel sizes was taken as the proper gravel size for Site X. The research results show that the formation at Site X is clayey sand with poor sorting and uniformity, proper gravel size for upper segment packing is 143−215 μm, while that for lower segment packing is 240−360 μm. In consideration of the difficulty of layered sand control operation on offshore platform, proper gravel packing size for Site X is recommended as 215−360 μm.