Storage, treatment and disposal of drilling cuttings in the environmentally sensitive areas and in severe weather conditions may create serious problems for economics, logistics, production and obtaining of appropriate permits and approvals. The oilfield waste management is one of the most critical challenge for the Russian oil and gas industry.
Waste re-injection back into formation is an ideal solution, which complies with the requirements applied to drilling and well production operations in the Russian Federation. Our field-proven experience allows to offer a cuttings re-injection package, which will benefit the waste disposal process in the most complicated work conditions by providing efficiency and economic parameters satisfying all appropriate requirements of the environmental legislation.
Storage and transport practices used for further treatment and disposal of wastes present additional challenges, that can be extremely costly for each project. Transportation of wastes is often impossible due to the poor weather conditions. In some cases, such restrictions may seriously affect the project and make it non-profitable. The cuttings re-injection system has been thoroughly developed and designed to settle such problems by treating cuttings on the rig, or in adjacent areas, thus reducing or excluding the necessity to transport cuttings from the rig or to truck them to distant locations. This approach gives an opportunity to the development of new oilfields, which were inaccessible due to the lack of road infrastructure.
Cuttings re-injection method is a solution, which fully complies with the requirements of the Russian Law. In addition to compliance with environmental regulations and zero-discharge polices, it ideally fits for environmentally sensitive areas, requiring serious restrictions for HC emissions versus any other waste disposal methods and technologies.
The safety and quality assurance process applied for the CRI purposes provides an integral approach to all aspects of the CRI project. Based on the analysis of the data provided by the Client, our specialists design special solutions, which are fully optimized for each particular project. Our CRI quality assurance and safety program is a unique product in oil and gas industry, as it allows verification of quality parameters before, during and after re-injection. This program enhances the safety of the project, including its economical profitability.
The unit is an integral part of the drilling waste injection system; it is designed to process different types of wastes and to convert them into slurry for further containment before injecting the slurry into formation. This unit has a small footprint, and it can be installed in a relatively small area. A conventional standard slurrification unit consists of the following components:
Drilling wastes are first collected into the coarse tank, where they are diluted with process water and/ or liquid wastes. At the same time, the large particles are broken down in the continuous circulation process activated by centrifugal pumps and power-driven agitators. There is an operator's station on the top of the tank; it is equipped with the control panels to control the slurrification process.
The drilling wastes are then directed to the shale shakers installed on the holding tanks. Liquid wastes and solid particles (<300 micron) are collected in the holding tanks, while the large particles, separated by the shale shaker, are directed to the blender installed on the top of the fines tank. Treated wastes are disintegrated in the fines tank by continuous circulation process, and then the material is fed into the shale shakers.
The dehydration tank is designed to improve the rheology of the slurry by adding chemicals through the hopper installed on this tank.
When the appropriate parameters have been reached, the slurry is directed to the HP pump for further injection into formation.
The total power consumption of the unit is 510 kW, the capacity is 240 m3/day.
Note* - the capacity of the unit may vary, as it depends on the type of drilled rocks and on the amounts of sand.
*to avoid fresh water contamination and uncontrolled propagation of fracture up the section and further on surface
**RF laws prohibit to place any wastes into reservoirs containing strategic reserves of the country
Test injection immediately after drilling and perforating the well helps assess and compare actual and estimated injection pressures. If estimated and actual injection pressures differ significantly, the geomechanical model should be adjusted. Then, "monitoring" is conducted in the course of cuttings re-injection
Cuttings re-injection monitoring is daily analysis of injection parameters, such as injection pressure, injection rate (flow rate), frictional pressure drop, pressure in fracture, fracture closure pressure and formation / pore pressure.
If injection analysis reveals there is a hazard of perforation holes being plugged by solids conveyed with drilling wastes, corrective actions are taken immediately: volumes and sequence of injecting viscous pills and flush fluid are adjusted, injection parameters are closely watched until they revert to normal.
Monitoring also helps assess how hydraulic fracture propagates: whether it goes up, expands laterally or expands in width.