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Friction calculation and packing effect analysis for gravel packing in deepwater horizontal wells

Gravel packing is one of the most commonly used well‐completion methods for controlling sand production in deepwater horizontal gas wells. Both the gravel‐packing mechanisms and the technical difficulties of gravel packing in a horizontal well are discussed in this paper. Subsequently, packing simulations were conducted based on geological data from a well in the LS gas field in the northern South China Sea. The factors influencing the gravel‐packing process were quantitatively analyzed. The influences of the pump rate, carrying fluid leak‐off ratio, and density of gravel on the sand‐dune ratio of the α‐wave, height of the sand dune, packing length of the α‐wave, and packing pressure were analyzed. The results show that the pipe string injection friction is the largest at the slurry injection stage and the α‐wave packing stage. In the β‐wave packing stage, the downhole horizontal flow friction becomes the main pressure loss. The friction increased when the β‐wave packing reached the heel of the horizontal wells. As a result, the packing pressure can easily exceed the formation fracture pressure. Furthermore, the lower the pump rate, the higher the sand‐dune ratio, which would cause premature screen‐out and blockage. Therefore, optimizing the pump rate is essential to ensure that the sand‐dune ratio meets the designed requirements. Under a certain leak‐off rate, the lower the gravel density, the longer the packing length of the α‐wave. For a long horizontal well, the step‐down method can be used to control the packing pressure during the β‐wave packing stage. The results provide technical support for field gravel packing.