Surge-and-Swab Pressure Predictions for Yield-Power-Law Drilling Fluids

Abstract

Summary Surge and swab pressures have been known to cause formation fracture, lost circulation, and well-control problems. Accurate prediction of these pressures is crucially important in estimating the maximum tripping speeds to keep the wellbore pressure within specified limits of the pore and fracture pressures. It also plays a major role in running casings, particularly with narrow annular clearances. Existing surge/swab models are based on Bingham plastic (BP) and power-law (PL) fluid rheology models. However, in most cases, these models cannot adequately describe the flow behavior of drilling fluids. This paper presents a new steady-state model that can account for fluid and formation compressibility and pipe elasticity. For the closed-ended pipe, the model is cast into a simplified model to predict pressure surge in a more convenient way. The steady-state laminar-flow equation is solved for narrow slot geometry to approximate the flow in a concentric annulus with inner-pipe axial movement considering yield-PL (YPL) fluid. The YPL rheology model is usually preferred because it provides a better description of the flow behavior of most drilling fluids. The analytical solution yields accurate predictions, though not in convenient forms. Thus, a numerical scheme has been developed to obtain the solutions. After conducting an extensive parametric study, regression techniques were applied primarily to develop a simplified model (i.e., dimensionless correlation). The performance of the correlation has been tested by use of field and laboratory measurements. Comparisons of the model predictions with the measurements showed a satisfactory agreement. In most cases, the model makes better predictions in terms of closeness to the measurements because of the application of a more realistic rheology model. The correlation and model are useful for slimhole, deepwater, and extended-reach drilling applications.

A novel oil-in-water drilling mud formulated with extracts from Indian mango seed oil

“…During circulation, if an operation stops for some operational reason, the gel strength and the yield point are key variables to suspending the cuttings from accumulating behind the drill bit. Nevertheless, high value of yield point leads to larger frictional pressure loss inside the wellbore and high circulation power to restart circulation (Crespo et al 2012). More than 50% reduction in the fluid loss was obtained with IMME (O/W) emulsion mud (3 mL) relative to the diesel-based mud (8 mL), which is advantageous especially when drilling through sensitive formations.…”

A Graphical Technique for Solving the Couette-Poiseuille Problem for Generalized Newtonian Fluids

“…The general solution of the Couette-Poiseuille problem (CPP), i.e. the flow between two parallel plates driven by pressure gradient and wall motion simultaneously is not only a fundamental problem of analytical fluid mechanics but it is also relevant in numerous practical applications, for example tape casting [1][2][3][4][5][6][7][8][9][10], damper modelling [11][12][13][14][15][16] or drilling [17][18][19][20][21][22][23]. If the rheological properties of the fluid are known, the flow properties such as e.g.…”

“…The importance of the CPP is especially high in wellbore hydraulics when trying to determine the surge and swab pressures. The most common geometry is an annulus with moving inner wall [17][18][19][20][21][22][23]. This type of flow is investigated by [23] for Robertson-Stiff, [17] for power law and in [45] for Bingham fluid.…”

“…This type of flow is investigated by [23] for Robertson-Stiff, [17] for power law and in [45] for Bingham fluid. The parallel plate assumption is valid in case of small clearances (compared to the radius), see [46], which is then used as a submodule in more complicated models as in [18,[20][21][22].…”

Down Hole Pressure Variation Due to Axial Stick Slip Motion Effect on Drill String

“…Generally, pressure variation depends strongly on drill pipe motion speed and flow behavior of the drilling fluid. Numerous studies have been undertaken to investigate the effects of fluid properties and drilling parameters through steady state fluid model (Burkhardt, 1961;Freddy Crespo, 2012;Ming, 2013). Also, dynamic surge/swab model has been developed to obtain more accurate prediction where pipe elasticity, fluid properties variations versus temperature and pressure has been taken into account (Mitchell, 1988).…”