Application and Study of Fine-silty Sand Control Technique for Unconsolidation Quaternary Sand Gas Reservoir, Sebei Qinghai
Sebei Gas Field is in the northeast of Caidam Basin, Qinghai, China. Its main pay-zone is unconsolidation quaternary fine-silty and dirty sandstones with serious sand production. A series of technique of comprehensive sand control with fiber-resin coated sand was successfully applied. The technique adopts formation pretreatment, clear brine-based viscoelastic surfactant fracture fluid as sand carrier, special glass fibers and resin-coated sand complex for fracture pack stabilization and enhanced proppant transport, frac-pack and TSO (tip screen out) for increasing productivity, bypassing near well bore damage, interconnecting multiple sandstone layers and decreasing fluid velocities in the formation to reduce fines production. This combined rehabilitation technique enabled screenless sand control completion, allowing low cost rehabilitation of plugged or failed sand screens and the development of any numbers of gas layers which otherwise could not be drained with conventional sand control technologies. The technique was exercised in well Se 3-18. Fine siltstones in the reservoir were adsorbed by the branched chain with positive electricity in the soft fiber and agglomerated into aggregation to avoid fine siltstones migration. The sand control fiber and the resin-coated sand were joined to establish stable three-dimensional network structure. Application of the clear brine-based fracturing fluid technique and TSO technique, propping belts with high diversion capacity could come into being and there was little formation damage.
