Application and Study of Fine-Silty Sand Control Technique Using Fiber-Complex High-Pressure Pack in Sebei Gas Reservoir

Abstract

Abstract Sebei Gas Field in Qinghai is the fourth largest gas field in China. The reservoirs here are of unconsolidated Quaternary siltstones and pelitic siltstones, alternating gas and water layers and with serious sand production. The grain size of the sands is very fine, so it is very difficult to realize sand control, a cosmopolitan puzzle. We have succeeded in applying a series of techniques of comprehensive sand control with fiber-complex high-pressure packing but without any screen pipe. The technology includes the reservoir pretreatment, the fiber- complex technique and the high pressure packing. As for the reservoir pretreatment, the soft fibers, of which the branched chains are with positive electrical charges, are used to adsorb the fine silty sand particles to form big aggregations for sand stabilization. As for the fiber-complex technique, the 3-dimensional reticular fiber and resin-coated sand complex are adopted for sand retention. As for the high pressure packing, the formation is not fractured while the fiber composites are packed to form screen pipe-like barrier around the cement sheath to perform sand control without any screen pipe used, eliminate any damage to the near wellbore zone and increase the gas bleeding area. This technique can achieve the dual purpose of sand control and production stimulation. This technique system had been applied in Well Se 7-1-4 in Sebei Gas Field with remarkable results achieved. After such sand control treatment, the output without sand production increased on average to 2.1 times of the output before. This paper presents mainly the relevant theory, experimental study, operation design and field application of the fine silty sand control technique using the fiber-complex high-pressure packing without any screen pipe.