Experimental Studies of Sand Production from Unconsolidated Sandstone Petroleum Reservoirs in Niger-Delta

Abstract

Production of sand during oil and gas exploration causes severe operational problem for oil and gas explorers especially companies producing from unconsolidated formations. Most reservoirs in the Niger-Delta fall in this category. Production oil and gas from such reservoirs has been limited by rate-dependent sand production and fines migration which resulted in near wellbore formation plugging. To prevent this occurrence, controlling the oil and gas flow rate will be of high importance to the oil and gas companies especially the producers operating in the Niger Delta. A physical model which has capacity for both consolidated and unconsolidated samples has been used to simulate the effect of flow rates, confining pressure, pressure drawdown and fluid viscosity on sand production in the Niger Delta. The model was also used to determine the ability of using the flow rate to control the production of sand. Sand sample from an unconsolidated reservoir in the Niger Delta was used in the model. Light and heavy crude oil with laboratory simulated brine was used as fluids as well. Results from the studies showed that the sand production increased as the following parameters; the flow rates, the confining pressure, the drawdown and the viscosity of the formation fluid are increased. The results also indicates that high sand-free flow rates can be achieved if the sand formation is mechanically confined (compacted). Further investigation revealed that sand production can be controlled by managing the flow rate alone when light oil was used while it is impossible to control sand production by managing the flow rate alone when heavy oil was used.