Application and Study of Fine-Silty Sand Control Technique for Unconsolidation Quaternary Sand Gas Reservoir, Sebei Qinghai

Abstract

Abstract Sebei Gas Field is located in the northeast of Caidam Basin, Qinghai, China. Its main pay-zone is unconsolidation Quaternary fine-silty and dirty sandstones with serious sand production. Grain size of the sand is very fine, about 0.04-0.07mm, so sand control is very difficult. In past ten years, many sand control methods (such as mechanical, chemical and frac-pack sand control) have been applied; however, expectant effect had not been achieved. Condisering the conditions of Sebai Gas Field, we succeed in applying a series of technique of comprehensive sand control with fiber-resin coated sand. The technique adopts formation pretreatment, clear brine-based VES (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; the results proved to be remarkable. Before sand control, serious sand production begins at 4.5×104m3; after sand control, sand production cannot be found at 91200 m3/d. Up to now, the well has been produced for nearly one year with stable gas production at 10×104m3 and no more sand production. This paper presents lab study, operation design, field operation and result analysis about the sand control technique.