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Experiments of gas–liquid flow in a circular pipe for horizontal and inclined positions (upward/downward) are reported. The characteristics of two-phase flow in terms of liquid holdup (ε(L)) and induced flow patterns are studied using three experimental techniques; time-averaged ε(L) from permittivity profiles using electrical capacitance tomography (ECT), instantaneous ε(L) using two fast-closing valves (TFCV), and high-speed camera images (HSCI) to capture/identify the formed flow patterns. Thus, this experimental setup enables the development of more well-defined flow patterns in gas–liquid two-phase flow and allows for multi-technique verification of the results. Taken from experimental measurements, a model is proposed to predict ε(L) for high and low situations. The correlations are a function of the hydrodynamic dimensionless quantities which provide hydrodynamic similarity. Regarding different pipe orientations, ε(L) predictions are comparable to ε(L) from experimental measurements with accepted accuracy: 88% of the predictions are within ±5–15% and 98% are below ±20%. The correlations also were validated by reported results and against correlations available in the literature and show higher prediction accuracy. It is confirmed that the kinematic similarity which is achieved by the gas–liquid velocity ratios and the inertial forces influence the flow pattern and the liquid holdup.

PurposeCasing completion is an extremely important part of the process of drilling and completing an oil well. This paper aims to focus on measuring corrosivity caused by drilling mud on casing materials using a simple method.Design/methodology/approachIn this experimental study a simple method is used to determine the effect of drilling mud on the two widely used casing string materials in the oil industry, carbon steel and J‐55 alloy. The drilling mud was formulated using Saudi local clay deposits, where mud viscosity at different clay concentration was measured to show the effect of clay content on mud apparent viscosity, and select the best formulation. The average weight loss of each type of steel was measured to show the corrosion rates, caused by a drilling mud formulated using collected clay samples. Viscosity measurements are shown.FindingsCorrosion in dynamic tests is higher than in static tests, and the Saudi clay muds were less corrosive on J‐55 alloy than on carbon steel.Originality/valueThe assessment method is a simple and fast way to predict maximum and minimum corrosion while drilling.

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As more engineering projects and activities are taking place on and around weak rocks, it is becoming more important to study and characterize them. Since regular practices of rock mechanical testing are not effective for weak rocks, special laboratory tests and measurements were performed to characterize the Alkharj Saudi weak sandstone rock which is a clastic rock dominantly sandy limestone and sandstone. Test results are presented in this paper. Porosity, permeability, and mechanical properties (stress, strain, Poisson's ratio, confined compressive strength and unconfined compressive strength) were obtained and then used to characterize the proposed weak rock. This paper provides a mean of classifying weak soft rocks despite encountered problems in handling and testing such materials.