As a rule, at gas fields, excavation pits (drilling waste pits) for storing drilling waste are constructed under extreme natural and climatic conditions, far from transport infrastructure, on waterlogged, permafrost and rocky soils, and this is most often compounded by a shortage of inert materials (sand).
Thus, pit-based drilling technology is used at the Kovykta gas condensate field – the largest gas field in Eastern Russia. Its use involves constructing drilling waste pits for long-term storage of drilling waste, with an area of up to 2 500 m2 for a single drilling rig. These structures pose a serious threat to the environment due to the risk of toxic substances entering the soils of the aeration zone and groundwater. This may occur due to the absence or poor-quality installation of waterproofing on the bottoms and sides of the pits.
Specialists from «TechPolymer» proposed an optimal technical solution for installing an impermeable barrier (IB) on the bottoms and slopes of the excavations, which compensates for the shortage of construction materials and provides reliable waterproofing for the drilling waste pits.
The main elements of the technical solution are the geocomposite drainage mat «Hydromat 3D» STO 56910145-005-2011 and the waterproof ge membrane TU 2246-001-56910145-2014 (type 5/1 – a polymer sheet thermally bonded to a protective and drainage coating made of nonwoven geotextile). «Hydromat 3D» will be used as a cushioning layer for the geomembrane. It is made as a three-dimensional grid with polymer rods arranged in a diamond pattern in three planes and protected on both sides by synthetic nonwoven material (geotextile).
The practical experience of «TechPolymer» in manufacturing and installing various IB configurations made it possible to take into account all the challenges involved in constructing settling pits at the Kovykta gas condensate field, providing a number of benefits:
uniform load distribution
The three-dimensional structure of «Hydromat 3D» acts as a cushioning layer and compensates for the absence of the required bedding layer. This promotes more uniform pressure distribution on the geomembrane impermeable barrier and increases its resistance to puncture or deformation on an unprepared subgrade.
effective moisture drainage
The in-plane drainage layer made of «Hydromat 3D» prevents conditions that could lead to microcracking and damage to the geomembrane under the influence of temperature fluctuations and mechanical loads resulting from frost heave.
environmental safety
Effective moisture drainage prevents the development of microorganisms and rotting, thereby reducing the negative impact on the environment.
Thus, applying the «TechPolymer» technical solution when installing an IB in excavations at the Kovykta gas condensate field minimised the risk of environmental pollution, compensated for the shortage of inert materials and reduced logistics costs.
