Sand Production during Improved Oil Recovery in Unconsolidated Cores

Steam injection is a mechanisms used for improved oil recovery (IOR) in heavy oil reservoirs. Heating the reservoir reduces the oil viscosity and causes the velocity of the moving oil to increase; and thus, the heated zone around the injection well will have high velocity. The increase of velocity in an unconsolidated formation is usually accompanied with sand movement in the reservoir creating a potential problem. Core samples from different wells in Kuwait were used to examine sand production during thermal injection in unconsolidated formation. A reservoir condition coreflood apparatus was used to inject oil with viscosities and flowrates. The oil sample was heated to give different viscosities, and the flowrate was increased gradually at each viscosity to establish the critical flowrate for sand production. At the end of the each test, the produced oil containing sand were filtered for sand content. The result showed that sand compaction at the injection face was more significant than sand production. Sand compaction resulted in permeability decline, whereas sand production improved the permeability. Sand production is a function of fluid and formation properties. The critical flowrate varied from 6 to 401 cc/hr for grain diameter of 277 to 366 μm, and at 684 cp viscosity oil. The critical flowrate varied from 3 to 87 cc/hr for grain diameter of 277 to 366 μm. Flowrate and viscosity of the oil, and the formation porosity, grain size, grain sorting, cementation, and overburden pressure, all contribute to sand production. Modeling all of these properties to predict sand production remains to be very challenging.