Study of the impact of the chemical treatment agents on the colmataging processes and the change of the permeability and porosity of the Tula Bobrikovian horizon cores

The article concentrates on the oil-field chemistry laboratory studies. The terrigenous reservoir cores of the Tula Bobrikovian horizon belonging to a range of PJSC Tatneft fields are a subject of the study in terms of the colmataging processes when treated with chemical agents (traditional acid-cut clay muds based on hydrofluoric acid and new suggested non-fluorine chemical agents (hereafter referred to as NFCA). Experimental physical methods show how using alkaline and acid solution based NFCA is promising in terms of the permeability and porosity improvement when modeling the process of well bore zone (hereafter referred to as WBZ) treatment in the terrigenous Tula Bobrikovian reservoirs belonging to PJSC Tatneft with minimized colmataging secondary sediment formation.
Materials and methods
The study of the cores of the main terrigenous development targets (Bobrikovian, Tula). Lithological, petrophysical studies are carried out along with the banding clay analysis. X-ray computer tomography is applied as a NDE method of the internal structure of the target.
Results
An instruction is developed based on the studies carried out during the pilot project for the technology of the BHT in the terrigenous deposit using a new formula for the non-fluorine agents (NFA). Main engineering solutions suggest works in eight wells in the current year.
Conclusions
The obtained results of the studies allow to formulate the following conclusions: 1) The carried out lithological, petrophysical studies of the banding clay has shown that an important additional typification of collectors is possible upon ‘composition and lithology of cement component’ criterion: clay-carbonate; carbonate-siliceous; clay-siliceous; 2) New knowledge about the typification justify the necessity and importance of specific selection of the chemical treatment formulae for each lithological and stratigraphic type of the reservoir even in one horizon; 3) Considering the specific selection, new non-fluorine based chemical formulae of selective (componential) chemical solubility of the rock in static conditions (core charge is in the scope of treating compositions), and in dynamic conditions of the filtration experiments with minimization of the sediment formation are justified and studied, the formulae correspond with ‘allowable corrosion’ and ‘compliance with oil’ criteria; 4) The carried out specific complex studies are relevant, and are aimed at increasing the efficiency of the terrigenous reservoir chemical treatment technologies; there are pilot projects planned for the current year with the use of the developed NFCA; the results are justified scientifically and experimentally, and are significant in terms of being a solution to modern business challenges of PJSC Tatneft.