INVESTIGATION OF THE IMPACT OF SULFONATED REFINERY PRODUCTS ON THE PROPERTIES OF WATER-BASED DRILLING FLUIDS

Abstract

The relevance of the work stems from the need to develop requirements for sulfonated bitumen applied in the composition of water-based drilling fluids to control their quality when entering drilling enterprises. Due to the presence of water-insoluble substances, sulfonated bitumens are considered to be hydrophobic bridging agents of clay rocks, though the proportion of water-soluble substances in their composition is much higher (~70 %). Nowadays the influence of the water-soluble component of sulfonated bitumen on clay rock in terms of inhibition and peptization is unknown. There are also no data on salt resistance and resistance to alkaline earth metals (Ca2+, Mg2+) of sulfonated bitumen. All this can lead to their irrational use. The study of these issues will help formulate requirements and select methods for assessing the quality of sulfonated bitumens, as well as improve the efficiency of their use in drilling fluids. The main aim of the research is to experimentally determine the functional properties of sulfonated bitumen in the composition of water-based drilling fluids. The main objectives of the research are to study the sulfonated bitumen effect on clay rocks and access the sulfonated bitumen resistance to mineralization and divalent cations. Objects: sulfonated bitumen samples of various brands and manufacturing plants. Methods. The technological parameters of clay drilling fluids were determined by standard methods in accordance with SS 33213-2014 (ISO 10414-1:2008); the inhibitory and peptization properties of the research objects in relation to clay rocks were studied by the method of clay swelling when they were in the sample solution (on the Zhigach–Yarov tester) and by means of sedimentary analysis (on the Figurovsky weight scale); salt resistance of sulfonated bitumens was determined by the method of sedimentation while placing sulfonated bitumens in a mineralized environment. Results. The authors have carried out the comparative analysis of six sulfonated bitumen samples to identify the physicochemical effect of this group reagents on clay rocks. By assessing the degree of swelling and particle-size determination of clay while its staying in the drilling fluids of the test samples, two groups of reagents of sulfonated bitumen were found, which are opposite in their functional effect on clay: 1) peptizing agents (deflocculants); 2) clay inhibitors. It was experimentally proved that all sulfonated bitumens contribute to the deterioration of the thixotropic, rheological, and filtration properties of fresh clay systems, while samples with inhibitory properties are more effective viscosity reducers; in a mineralized environment, the presence of divalent cations and sulfonated bitumens are conductive to a decrease in filtration properties, but are ineffective as viscosity reducers, and also, they are conductive to thickening due to their coagulation or solubility decrease. Experiments proved that for determining the functional purpose of high-molecular-weight sulfonated bitumens in the composition of water-based drilling fluids and controlling the quality of the samples, it is necessary to test them according to the following indicators: to determine the size of clay particles in water and in a solution of the test sample in order to identify its inhibitory or peptizing properties; to evaluate the thinning capacity and the effectiveness of reducing the filtration characteristics when adding a reagent to a fresh clay suspension.

Keywords

• drilling fluids
• sulfonated bitumen
• sulfonated asphalt
• clay swelling inhibiting
• clay dispersion
• coagulation