Application and Study of Fine-silty Sand Control Technique for UnconsolidationQuaternary Sand Gas Reservoir, Sebei Qinghai

摘要

Sebei Gas Field is located in the northeast of Caidam Basin,Qinghai, China. Its main pay-zone is unconsolidationQuaternary fine-silty and dirty sandstones with serious sandproduction. 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 andfrac-pack sand control) have been applied; however, expectanteffect had not been achieved. Condisering the conditions ofSebai Gas Field, we succeed in applying a series of techniqueof comprehensive sand control with fiber –resin coated sand.The technique adopts formation pretreatment, clear brinebasedVES (viscoelastic surfactant) fracture fluid as sandcarrier, special glass fibers and resin-coated sand complex forfracture pack stabilization and enhanced proppant transport,frac-pack and TSO (tip screen out) for increasing productivity，bypassing near well bore damage, interconnecting multiplesandstone layers and decreasing fluid velocities in theformation to reduce fines production. This combinedrehabilitation technique enabled screenless sand controlcompletion, allowing low cost rehabilitation of plugged orfailed sand screens and the development of any numbers ofgas layers which otherwise could not be drained withconventional sand control technologies.The technique was exercised in well Se 3-18; the resultsproved to be remarkable. Before sand control, serious sandproduction begins at 4.5×104m3; after sand control, sandproduction cannot be found at 91200 m3/d. Up to now, thewell has been produced for nearly one year with stable gasproduction at 10×104m3 and no more sand production. Thispaper presents lab study, operation design, field operation andresult analysis about the sand control technique.