Land spraying, also known as land spreading, mud spraying or land application, is the process of spraying water-based drilling mud on agricultural
It is recognised by the Queensland Government as an environmentally friendly way to dispose of residual drilling material, or drilling mud,
that is produced from drilling a well.
The process reduces the need to construct on-site disposal sumps for this material.
During the well drilling process the mud is stored in rig tanks, processed and then applied onto flat land using a purpose built vacuum truck
or similar machinery.
The areas are carefully selected and the application of potassium-rich drilling mud to agricultural soil may lead to improved water holding
capacity and plant growth.
The process is regulated by the Department of Environment and Science which ensures
only tested and approved fluids are applied to flat land well away from any waterways.
Drilling mud is essential to the well drilling process for:
- Carrying cuttings from the hole
- Cooling and cleaning the drill bit
- Reducing friction
- Maintaining the stability of the bore
- Maintaining down-hole pressure
The exact amount of drilling mud produced depends on several factors including the depth of the well being drilled.
Residual drilling material is a mix of water and rock fragments that is brought to the surface during drilling operations, plus a small percentage
of additives (0.1%) that are needed to lubricate the drill bit and ensure the required mud consistency for the drilling process.
The composition of additives is adjusted according to the location’s physiochemical and geological conditions.
Any additives used in the drilling process must be approved by the Department of Environment and Science to ensure they are non-hazardous to
the environment and personnel.
All Queensland petroleum operators use water-based additives as they are prohibited from using any synthetic-based additives.
More information about the regulation of residual drilling material in petroleum activities can be found by phoning the Queensland Government
on 13 QGOV (13 74 68).
Agricultural land after land spraying
Streamlined model conditions for petroleum activities - page 16 (PDF 1.36MB, Department of Environment and Science guideline)
Characterisation and management of drilling fluids and cuttings in the petroleum industry (PDF 72KB, Department of Environment and Science)
Department of Environment and Science website