The Application Of Specialist Hydrocyclone For Separation And Clean-Up Of Solids In The Oil And Gas Industry
Authors: Hodson J.E. , Childs Geoff , Palmer A.J. 
Published: October 2008

Although technologies do exist for removing solids from waters, oils, drilling fluids and sludges in the oil and gas industry, the capital and operating costs related to solids removal and cleaning can be very high and greatly reduce the economics in offshore oil and gas processing drilling technologies and many other sludge cleaning operations.

For the past four years Chevron UK Limited and Richard Mozley Limited UK have been developing hydrocyclone technology, based on the minerals industry, for applications in solids removal and clean-up in the oil and gas industry.

The flexibility of hydrocyclone with respect to fluid rate, solid type, solid concentration pressure, temperature, etc. enables them to be used for many different process applications.

In addition the size, weight, cost and absence of moving parts make the hydrocyclone attractive when compared with alternative technologies. This improves the economics of offshore developments particular for small field development and simple retrofitting to existing field.

This paper discusses the results of:Laboratory and field trials for removal of solids from brine/produced water for injection into reservoirs.Laboratory trials for cleaning oil from solids.The applications of the technology for offshore oil, gas and drilling process.Application of the technology to reduce environmental pollution

SURVEY OF APPLICATIONS

In nearly all offshore oil and gas field developments, solids present a major problem in optimizing processes and make operations difficult for many unit operations. Hydrocyclone technology can replace present offshore technologies reducing the size, weight and cost of the operations. These include:-Replacement of coarse and fine filters for sea-water filtration. Sea-water can be taken from a lower water-depth, below the possible ‘ algae bloom’ depth. For low permeability reservoirs the hydrocyclone may have to be used in conjunction with other filtration methods.Re-injection of produced water reduces the sea-water filtration and deaeration capacity required for reservoir pressure maintenance. Also, this has a major impact on the environment by reducing oil and solids discharge into the sea.Solids removal from separators and reducing the oil level on the solids to the accepted environmental requirement.Removing sand from gas/condensate field fluids to reduce pipeline deposition and erosion.Removing oil from drilling cuttings.Cleaning reservoir rock, debris or cuttings from drilling operations.Recovery and cleaning of solids from oil and water based muds.

In the offshore oil and gas industry, removing and cleaning solids from oil will significantly reduce environmental pollution. Solids can be returned to the natural environment in many instances. If the quantity of residue is sufficiently small it may be economic to transport to a land-fill site.

HYDROCYCLONE TECHNOLOGY DEVELOPMENT

The Mozley hydrocyclone used in the minerals industry have been developed since 1977 for removing a wide range of particle sizes.

Figure 1 is a graphic example of efficiency curves (percentage recovery of the size fractions to underflow) for different sizes of hydrocyclone. Figure 2 shows the operation of a hydrocyclone.