A separate-layer chemical sand control technology suitable for heterogeneous sandstone oil reservoirs

Commingled chemical sand control is disadvantageous with short period of validity and low success rate. In this paper, the separate-layer chemical sand control technology used for heterogeneous unconsolidated sandstone oil reservoirs was researched. First, considering the crude oil on the surface of sand grain is the main factor impacting the effect of chemical sand control, a high-strength, high-permeability and oil-resistance sand control system suitable for the reservoir temperature of 45-150 ℃ was researched and developed. When this system is added into the oily sewage (crude oil content 10%), its consolidation strength is 6.2 MPa, permeability retention rate is 92.5% and viscosity is lower than 5 mPa · s. Second, low-temperature and high-strength AB sand was developed. Its consolidation strength can reach 7 MPa under the temperature of 40 ℃. It solves the problem of Shengli Oilfield in the late stage of development when the sand control failed due to the low bottom hole temperature and the low consolidation strength of conventional coated sand. And third, a separate-layer chemical sand control string that has the ability of anticreep and can carry out large-displacement inverse well flushing and inject sand control agent or coated sand selectively through one-trip string was designed. And it addresses the short period of validity of commingled chemical sand control in heterogeneous oil reservoirs and the complex procedure and poor reliability of conventional separate-layer chemical sand control string. In conclusion, this new technology improves the adaptability of chemical sand control to heterogeneous unconsolidated sandstone oil reservoirs and is of great significance to ensure the sand control production effects of silty-fine sandstone oil reservoirs and oil/water wells with special borehole.