Voloshyn Y. Improvement of the wells development technology with low-permeability productive horizons

Voloshyn Yu. D. Improvement of well development technologies with low-permeability productive horizons. ‒ Qualification scientific work on manuscript copyrights. Dissertation for obtaining an academic degree of Candidate of Technical Sciences (doctor of philosophy) in major 05.15.10 ‒ Well drilling. ‒ Ivano-Frankivsk National Technical University of Oil and Gas, Ivano-Frankivsk, 2023. The current state of well development technologies with low-permeability productive horizons is analyzed and some directions for their improvement are substantiated. Using experiment planning methods, the effect of vibration with frequencies of 20 – 130 Hz and sulfonol concentration of 0,1–2,0% on the bending strength of the rock model was studied. A statistically significant effect of sulfonol concentration on the strength index of the isotropic rock model has been established. An equation of regression of the strength indicator from the concentration of sulfonol and vibration frequency is constructed. The effect of cyclic loads on the filtration and strength properties of artificial and natural cores has been studied. The presence of dominant frequencies has been established, some of which are effective for technologies for cleaning the blasting area of boards, and others ‒ to initiate the growth of fatigue cracks. The results obtained give grounds to recommend frequencies in the range of 25‒100 Hz and can be used to justify the design of technologies for the development of wells with pulse-wave treatment of the bottom-hole formation zone. A three-level hierarchical model for selecting the optimal formulation of process fluids for well development has been proposed. At the first level, using fuzzy decision-making models, the choice of a subset of equivalent formulations is substantiated, at the second − optimal formulation and its component composition and at the third − the composition of two (neonol and solpen) surfactants (SAR) to provide the necessary surface properties at the phase section boundary of the filtrate of the process fluid – reservoir fluid. For the conditions of low-permeable collectors, a biopolymer-based well-killing fluids proposed. Based on the studies conducted, correlations and regression dependencies between some technological and surface properties of the well-killing fluid and concentrations of surfactant and sodium chloride have been established. The choice of the type and content of surfactant in process fluids based on aqueous solutions of inorganic salts is substantiated. According to the results of the conducted studies, a method for selecting formulations of technological liquids by minimum values of interphase tension and the study of the effect of surfactant content on the viscosity of oil-water emulsions with different W/O ratios was proposed. The choice of parameters of pulse-wave action technologies on the bottomhole formation zone is substantiated in order to increase the efficiency of well development with low-permeability collectors. At the same time, the main attention is paid to the choice of amplitude-frequency characteristics, the duration of processing and depression on the layer. On the example of mining and technological conditions of the Bugruvativk oil field, the choice of optimal formulations of well-killing fluids according to the criteria of unit cost of volume (78 $/m3), the minimum interphase tension at the phase boundary of the filtrate of the liquid – oil (1.24 mN/m) and effective remoteness is substantiated. During the testing of the development technology using pulse-wave impact on the productive horizon, an engineering approach was implemented to select a candidate well, the formulation of the process fluid and the parameters of the combined pulse-wave depression treatment of the bottom-hole formation zone. The results of testing in industrial conditions at the well 63-Duzlak indicate positive effects due to the cleaning of the bottom hole zone from high-viscous colmatant with a volume of 3.5 m3 and successful development of the well.