Sulphate Separation from Seawater by Nanofiltration

An oilfield is comprised of oil, natural gas and what is known as formation water. Initially oil will rise up the well due to natural pressure within the reservoir. In order to maintain a high pressure and to enhance recovery of oil, seawater may be injected around the edges of a reservoir. Later in the life of a producing oilfield, a mixture of oil and water is produced from the well. This water can be a mixture of formation water and injected seawater. For some oilfields there is a problem when the seawater meets the formation water as the latter may have high concentrations of both barium and strontium which react with the sulphate in the seawater. The reaction products are precipitates which block the pores in the rock and scale the pipework on the platform. In some instances the problem can be so severe that the production wells become blocked.