DPV Service Sp z o.o.

DPV Service owns the Underground Waste Storage facility Otyń, which it operates under license No. 6/2006/s. The license was granted by the Minister of the Environment for storage of liquid waste in rock deposit located in depleted oil and gas field "Otyń" located in the municipality Otyń, Nowa Sól powiat, Lubuskie voivodeship. The license permits the activity of non-reservoir storage liquid waste with code 01 01 02 (classified on the basis of the Minister of Environment of 27.09.2001 on catalog waste OJ No. 112, poz.1206). The  Otyń IG-1 well was reconstructed and is now used for this purpose, upon cessation of natural gas and crude oil production operation from the Zechstein Main Dolomite. Liquid waste with stored waste code 01 01 02 is a by-product of crude oil and natural gas production containing certain quantities of specific substances.

The injection well technology is an alternative to other expensive and often ineffective methods of storage or disposal of liquid waste. Especially so where the existing water regulations do not allow for discharge of wastewater, containing saline solutions and other chemicals used in preparing drilling solutions and cement slurries, waste oil, acid and alkaline solutions, detergents and mine waters with high mineralization into surface waters or into the ground. The Waste Management Act also prohibits storage of liquid waste with water content in amounts greater than 95% of the total weight.

Disposal of liquid waste through injection into the rock formation and injection wells technology is completely safe, and the method consists of irretrievable pumping of treated waste into deep, closed geological structures with particular characteristics and specific collector capacity, which, together with a package of rocks form an impervious protective screen for usable aquifers shielded from uncontrolled migration. It is those places with isolated natural traps in which accumulation of oil and natural gas may have been for millions of years.

The technology unloading, storage and waste injection ensures the enclosure of the entire system, and hence, can operate safely, without compromising the environment. The area around the unloading place and the collector field reservoir are sealed with geomembranes. The whole process is hermetic and is subject to continuous monitoring.

Storage of liquid waste underground in depleted parts of Zechstein Main Dolomite fields is the most environmentally safe way of liquid waste disposal.

This method is unmatched in economic terms, particularly in the case of adaptation of existing wells in depleted hydrocarbon fields.

In sum

Three types of security mechanisms exclude contact of injected waste with groundwaters used for potable purposes.

The first security mechanism is the basic geological structure. Underground arrangement of rocks below the surface is the natural and the most efficient insulation. Rock formations into which reservoir liquids are injected is at a depth of 1612 m. and is sheltered by a series of impermeable sediments: anhydrite, salt, claystones and siltstones.

The second security mechanism is in the construction of the absorbent well, through which reservoir waters are injected. The whole well length is protected by four columns of steel pipe connected with the surrounding rocks with the cement mantle. Inside these pipes runs a special pressure tube (the syfonówka) additionally sealed at its lower end (the packer). The space above the packer is filled with special liquid (the forepacker liquid). The top of the well is armed with a well head for operating oil or natural gas production facilities. Approved pressure is 35 MPa.

The decision for reservoir water and liquid waste injection into a geological structure "Otyń" through Otyń - IG-1 well is based on several geological studies, such as:

• Documentation outlining the hydrogeological conditions of dolomite within the main structure Otyń including depleted petroleum and natural gas in the main dolomicie.
• Evaluation of geological conditions - within the rock engineering structure involving Otyń exploited oil and natural gas in the main dolomicie.
• Report on environmental impact of the project located on parcel number 234 / 1 in Zakęcie, gmina Otyń, Nowosolski powiat,
• Documentation deposits of crude oil and natural gas Otyń, ZZGNi G. Zielona Góra, 2000

and literature:

• Karnkowski P. - Oil and gas deposits in Poland. Edited by W. Gorecki, Geosynoptics Society "Geos", Cracow, 1999.
• Kijewski P. - deep saline injection. Zeszyty Naukowe AR. Wroclaw. 1993
• Environmental Engineering III
  An Introduction to the Technology of Wastewater subsurface injection.
  U.S. Environmental Protection Agency, Ada, Oklahoma, December
  1997, and a vision of a field.

With regard to hydrogeology, filling in the Main Dolomite with liquid waste will return the shattered in the horizon, which resulted from extraction of bitumen, to hydrostatic equilibrium.

Liquids, other than reservoir waters, will certainly engage in chemical reaction with reservoir rock formation because of their highly variable chemical composition. The result of such reactions may be:

• extension of microcracks or pores in the reservoir rock when it is in contact with acidic liquids, and soluble reaction products (mainly salts) will be seeped with the forehead area of waste ground, and their concentrations will undergo a gradual decrease;
• near-well sealing zone due to precipitation of the reaction products of low-or insoluble in brine (reservoir water).

According to the assumptions injected fluids will cause both the first and second type of reaction with the rock. The opposing effects of these reactions (dissolution or precipitation) is that as the result will remain neutral with respect to the strength parameters of the reservoir rock. A change in chemistry within the impact zone of the waste collector will not have a significant negative effect with regard to storage for both the collector and above geological formations.

Conclusions

Each industry produces waste, even with the contemporary use of both innovative and traditional processes. These are both solid and liquid waste. Environmental protection law obliges the manufacturers to rational management of their waste. Storage and warehousing of waste has taken on special significance recently. For the amendment to the Environmental Protection Act followed the amendment to the Geological and Mining Law, which provides the legal framework covering the issue of use of underground mining works for these purposes.

In the current economic situation Poland is not able to bear the burden of the costs of innovative technologies, and having the underground reservoirs provide the conditions for the safe and economical disposal of waste.

The activities carried out by DPV Service are environmentally-concious, safe and economically reasonable.

Prof. dr hab. Eng. Tadeusz Zaborowski