The aim of this article is to discuss the problem of drilling waste remediation. Analyses and research showed that material stored in waste pits could be classified as soil with a high level of petroleum impurities (total petroleum hydrocarbons [TPH] = 102,417—132,472 mg kg^—1 dry mass). While preparing the complex technology of soil decontamination (which included primary reclamation, basic bioremediation and inoculation with biopreparations based on indigenous bacteria and fungi), laboratory tests indicated the use of an ex-situ method was fundamental. Remediation was controlled with a chromatographic method of qualitative and quantitative determination of petroleum hydrocarbons. Based on analytical data, there was the possibility to determine the effectiveness of consecutive purifying phases. Laboratory tests, following 135 days of basic bioremediation stimulated by optimum conditions to activate the growth of indigenous micro-organisms, resulted in a decrease in the TPH content, which was in the range of 52.3—72.5%. The next phase of soil decontamination lasted 135 days and involved the use of inoculation with biopreparations based on indigenous micro-organisms and fungi. This process enabled a TPH decrease of 93.8— 94.3%. Laboratory biodegradation research was done with the use of the biomarker C₃₀-17α(H)21β(H)-hopane to normalize analyte (TPH, Σ n-C₈— n-C₂₂ and Σ n-C₂₃— n-C₃₆) concentrations. The calculated first-order biodegradation constants enable estimation of the purification stage dynamics and the effectiveness of the applied biopreparations. Furthermore, they represent the biodegradation degree of individual n -alkanes in subsequent stages of the soil purification process.

An analysis of environmental threats showed that the complete influence of shale gas production on the environment is bigger than in the case of gas production from a traditional oilfield. Hydraulic fracturing of shale, done on a much larger scale, results in huge amounts of liquid waste that must be managed in a rational way. An optimum solution to this problem is reusing flowback water to develop fluids for later fracturing. This article discusses the composition of the fluids used in hydraulic fracturing of non-conventional deposits as well as the flowback water. In the case of the examined liquids, toxicological tests have been carried out using microbiotests of ToxKit types Microtox, MARA, Daphtoxkit F magna, and Thamnotoxkit F. The research was done on a sample of fluids for hydraulic fracturing, and on flowback water obtained in hydraulic fracturing of shale formations in Poland. The tests are essential for correctly managing flowback waters after fracturing.

The extraction of hydrocarbons is associated with obtaining certain amounts of water, which is heavily contaminated with a wide range of chemical compounds that negatively affect the environment. At present, practically the only method of managing extracted reservoir waters is their injection into absorbing horizons. Large changes in parameters (pH, Eh, temperature, etc.) occurring during the extraction and storage of water, as well as the contact of the injected water with reservoir water and rock, may result in the precipitation of secondary sediments. The complexity of the injected water/native water/deposit rock system and the wide range of possible interactions do not always allow for correct interpretation of the processes and their impact on near-well zone permeability. One of the factors which has a decisive influence on dissolution/precipitation is temperature change. Applying analytical data of water with low (W-1) and high (W-2) mineralization, calculations were carried out with the use of PRHEEQC software. Changes in solubility index values were determined at ambient temperature (20 °C) and reservoir temperature (94 °C). The obtained results indicate that with increasing temperature, SI changes for a given chemical compound may run in different directions and take different values, depending on the composition of the injected water. The calculations indicate the possibility of a change in the direction of the reaction from dissolution to precipitation, which may lead to clogging of the near-well zone. Simulations of the injected water’s contact with minerals present in the reservoir rock were also carried out. The obtained data indicate that these minerals, in the entire studied temperature range, dissolve in the injected water, but the solubility of anhydrite and dolomite decreases with increasing temperature. If the water is saturated with minerals at low temperature, after heating in the bed, sedimentation and blockage of rock pores may occur, which means there is a reduction in the efficiency of water injection.