Aim of the project is efficiency increase of hard rocks destruction at borehole bottom by developing drilling mud solution and evaluation of its influence on drilling process. The article presents the results of studies directed on studying of drilling mud composition (the choice of reagent concentrations, taking into account the filtration properties, structural and rheological parameters, study of the temperature effect influence on the quality of the solution). Experiments of metallic indenter penetration into the glass sample at various number of strikes in the water and surfactant solutions are presented in the article. Paper also offers investigation devoted to development of clayless mud solution with surfactant addings, which will allow increase of hard rocks destruction efficiency. Results of industrial test trials of developed mud solution are also represented, showing implementation of developed drilling mud composition to increase productivity of drilling operations by maintaining high drilling speed and advance per bit.

CMC polymer is used as an additive to decrease water loss and mud-cake-thickness in mud drilling. In this study, the effect of CMC and CMC nanoparticles on water loss and mud-cake-thickness in mud drilling is investigated. CMC nanoparticles are made by using of ball milling and their size is measured by Particle size analyzer. CMC and CMC nanoparticles which were prepared by Hamilton batch mixer and with certain percent suggested by API, were added to the water-based mud drilling. The amount of water loss and mud cake thickness was measured by filter press. It was found that adding CMC nanoparticles in comparison with conventional CMC resulted in desirable reduction of amount of water loss and mud cake thickness.

Filtration index of the drilling fluid is an important parameter of well drilling, especially at drilling-in the reservoirs. Standard parameter in the study of drilling fluids is static filtration index. At the same time, it is more feasible to determine dynamic filtration index, if considering actual conditions of the well. Use of polymer carbonate-weighted drilling fluids is advisable at drilling-in oil and gas formations; but, it is also necessary to take into account fractional composition of the weighting agent. Aim of the work is to study the influence of weighting-bridging agent's fractional composition on drilling fluid's dynamic filtration index. Taking into account main theories of bridging agent selection, such as the theory of Abrams, Kaeuffer and Vickers, will make it possible to define the influence of carbonates “ blend” on the filtration losses of the drilling fluid. Dynamic high pressure high temperature (HPHT) filter was used in this research, which allows measuring filtration properties of the drilling fluid as in standard HTHP test, with fluid circulating inside the cell. In order to get results that are closer to real conditions, in addition to the standard paper filter, studies were carried out on ceramic disks with a known porosity. Theories on selection of bridging agents considered in the paper have their advantages and disadvantages. Depending on available data on the reservoir (for example, data availability on porosity and permeability) and access to high-quality bridging material, a more effective theory is chosen and the negative effect of the drilling fluid on the productivity of the formation is reduced.

Drilling cost optimization has always been an important issue in the petroleum industry. In order to save costs and create new markets for local materials, Detarium microcarpum also known as ofor and food gum (Cissus populnea) powders were evaluated in this study at high temperature as an alternative to imported chemical additives in water-based drilling fluid. The base mud composed of alkali beneficiated local clay, Brachystegia eurycoma also known as achi, corn and cocoanut fibers whose viscosity, yield point and gel strength fell short the recommended API standard from preliminary analysis. The two factors were combined using experimental design technique and mud properties optimized numerically using desirability function. At optimum conditions, The mud’s properties are as following: Plastic viscosity, PV (18.4±0.63 cp), Yield point, Yp (15.7±0.9 lbf/100ft2), Fluid loss (FL) (12.1±0.37 ml) and 10 min Gel strength (5.6±0.05 lbf/100ft2). These values are in good agreement with the API recommended standard. Both biopolymers exhibited high potential at low and moderate temperatures. However, food gum is thermally stable, a good rheology stabilizer and filtrate reducer up to the test temperature of 185oF. The presence and nature of salts in solution influences differently the viscosity of the two biopolymers.