NUMERICAL SIMULATION OF TRANSIENT CUTTINGS TRANSPORT WITH FOAM FLUID IN HORIZONTAL WELLBORE

With considering the interlayer mass transfer and fluid influx from the reservoir, a one-dimensional two-layer hydraulic model was established to describe the mechanism of transient cuttings transport with foam fluid in horizontal well section. The model was numerically calculated based on the modified SIMPLE algorithm, and the height of cuttings bed was predicted by the trial-and-error method. Sensitivity analysis was conducted on the affecting factors on the cuttings transport performance. Results show that cuttings deposition moves along the horizontal wellbore from the drilling bit, and finally achieves a steady state with dynamic balance. Dimensionless cuttings bed height decreases with the increase of foam quality or foam flow rate, but increases with the increase of drillpipe eccentricity, cuttings size or drilling rate. The influx of water and gas from the reservoir is helpful to improve the cuttings transport efficiency with foam. The proposed model offers theoretical guidelines for hydraulic parameter design and hole cleaning control in foamed horizontal drilling.     

TRANSIENT PRESSURE BEHAVIOR FOR HORIZONTAL WELL IN DOUBLE-POROUS MEDIA

ＴＲＡＮＳＩＥＮＴ　ＰＲＥＳＳＵＲＥ　ＢＥＨＡＶＩＯＲ　ＦＯＲ　ＨＯＲＩＺＯＮＴＡＬ　ＷＥＬＬ　ＩＮ　ＤＯＵＢＬＥ－ＰＯＲＯＵＳ　ＭＥＤＩＡＴＲＡＮＳＩＥＮＴＰＲＥＳＳＵＲＥＢＥＨＡＶＩＯＲＦＯＲＨＯＲＩＺＯＮＴＡＬＷＥＬＬＩＮＤＯＵＢＬＥ－ＰＯＲＯ...     

WELL TESTING ANALYSIS FOR HORIZONTAL WELL WITH CONSIDERATION OF THRESHOLD PRESSURE GRADIENT IN TIGHT GAS RESERVOIRS

A fundamental solution for homogeneous reservoir in infinite space is derived by using the point source function with the consideration of the threshold pressure gradient. The fundamental solution of the continuous point source function is then derived based on the Green function. Various boundary conditions of the reservoirs are considered for this case and the corresponding solutions are obtained through the mirror image reflection and the principle of superimposition. The line source solution is obtained by integration. Subsequently, the horizontal-well bottom hole pressure response function for a non-linear gas flow in the homogeneous gas reservoir is obtained, and the response curve of the dimensionless bottom hole pressure and the derivative for a horizontal well in the homogeneous gas reservoir are obtained. In the end, the sensitivities of the relevant parameters are analyzed. The well test model presented in this paper can be used as the basis of the horizontal well test analysis for tight gas reservoirs.     

水平液面式孔内电视系统测量孔斜的误差因素

提出水平液面式孔内电视系统测量孔斜的误差因素。并对液体的毛细作用、误差精度、钻孔顶角、容器直径引起的误差进行分析。     

A STUDY ON TRANSIENT FLUID FLOW OF HORIZONTAL WELLS IN DUAL-PERMEABILITY MEDIA

To adopt horizontal wells in dual media reservoirs,a good understanding of the related fluid flows is necessary.Most of the recent studies focus on dual porosity media instead of dual permeability media.In this article,through both integral transformation and sink-source superposition,a new Laplace-domain solution is obtained for the slightly-compressible fluid flow in the 3-D dual-permeability media in which the horizontal well is operating in a constant rate of production.Major asymptotic characteristics of diagnosis curves of dimensionless downhole pressure are analyzed by the limited analysis.Effects of parameters of dual-permeability media including mobility ratio κ,storativity ratio ω and inter-porosity flow parameter κ on the downhole pressure are studied by using the Laplace numerical inversion.The new solution obtained in this article includes and improves the previous results and then can be used as a basis for either pressure transient analysis or formation behavior evaluation for the typical reservoir with horizontal wells.     

A SECOND-ORDER MOMENT TURBULENCE MODEL FOR POWER LAW FLUID WITH PARTICLES

The USM-θ model of power law fluid for dense two-phase turbulent flow was developed, which combines the unified second-order moment model for two-phase turbulence with the particle kinetic theory for the inter-particle collision. This model was used to simulate the turbulent flow of power law fluid single-phase in pipe. It is shown that the USM ? θ model has better prediction result than the k f ? ε f?kp?εp?θ model. The USM ? θ model was then used to simulate the dense two-phase turbulent up flow of power law fluid with particles. With the increase of the flow exponent, the velocities of power law fluid and particles increase near the pipe centre. Comparison between the two-phase flow of power law fluid-particle and of liquid-particle indicates that the axial fluctuation velocity of fluid phase and particle phase in liquid-particle two-phase flow is smaller than that in the power law fluid two-phase flow, but the two-phase velocities of power law fluid-particle and liquid-particle are close to each other.     

A COUPLED THERMO-HYDRAULIC MODEL FOR STEAM FLOW IN PIPE NETWORKS

This article aims to establish a coupled thermo-hydraulic mathematical model for steam network by adopting a set of equations, i.e., the continuity equation, motion equation, energy equation, state equation and enthalpy equation and considering the interaction of hydraulic and thermal working conditions. The model is simplified according to steam flow features in pipe networks. The unsteady flow model is simplified to a steady one with considering engineering practice and the solution to the governing equations are obtained by using the standard fourth-order Runge-Kutta method. Many factors of steam flow are generally considered, such as condensability, change of state, friction and heat transfer in the model. It is concluded that coupled iteration can be employed in steam network thermo-hydraulic computation. The numerical results with the model are basically in accordance with practical operation data.     

A HYBRID MODEL FOR THE MERGING OF JETS IN A COFLOWING AMBIENT FLUID

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＧｅｎｅｒａｌｌｙｔｈｅｄｉｓｐｅｒｓｉｏｎｏｆｊｅｔｓａｎｄｐｌｕｍｅｓｉｎａｍｏｖｉｎｇｅｎｖｉｒｏｎｍｅｎｔｃａｎｂｅｒｅｌａｔｅｄｔｏｔｈｅｄｉｓｐｏｓ ａｌｏｆｕｒｂａｎａｎｄｉｎｄｕｓｔｒｉａｌｗａｓｔｅｗａｔｅｒ     

A NEW METHOD FOR PREDICTION OF PRODUCTIVITY OF FRACTURED HORIZONTAL WELLS BASED ON NON-STEADY FLOW

Hydraulic fracturing technologies of horizontal well are important ways to develop oil-gas field with low permeability. Productivity forecast of fractured horizontal wells is a difficult problem of hydraulic fracturing technologies. Basing on non-steady flow of fractures fluid during production, applying potential function principles, superposition principle and mathematical method for solving, coupling of seepage flow in the formation and pipe flow in the well bore, a new model on multi-fracture interference productivity forecast of fractured horizontal well is established in this article. The results indicate the coincidence rate between this model and practice is high. The pressure loss in the horizontal well bore has definite influence on the production status of fractured horizontal wells. The productions of different fractures in horizontal well bore are unequal, the productions of outer fractures are higher than middle fractures; the pressure in the well bore shows an uneven distribution, the pressure declines gradually from finger tip to heel end. Asymmetry of fractures may make productivity of fractured horizontal wells decline. The conclusions are instructive in designing fractured horizontal well for low permeability reservoir.     

A CONSERVATIVE COUPLED FLOW/TRANSPORT MODEL WITH ZERO MASS ERROR

A fully conservative form applied to a coupled system of two-dimensional water flow and solute motion is presented. A cell-centred finite volume method based on Roe's approximate Riemann solver with unstructured grids is formulated. The bed slope source terms are discretized following an upwind approach and a semi-implicit treatment is used for the friction source terms. The centered discretization of the diffusion terms is in an implicit way. It is shown that this numerical technique reproduces almost exactly the steady state of still water and enables to achieve zero numerical errors in unsteady flow over configurations with strong variations on bed slope. The model ensures a global conservation and positive values of both water level and solute concentration. Numerical results show the effectiveness of the model in solute transport over real complex geometries.     

A MATHEMATICAL MODEL FOR UNSTEADY SEDIMENT TRANSPORT IN NINGXIA REACH OF THE YELLOW RIVER

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＮｉｎｇｘｉａｉｓｌｏｃａｔｅｄｉｎｔｈｅｗｅｓｔｅｒｎｐａｒｔｏｆＣｈｉｎａ .ＴｈｅＹｅｌｌｏｗＲｉｖｅｒｐｌａｙｓａｎｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｔｈｅｄｅｖｅｌ ｏｐｍｅｎｔｏｆＮｉｎｇｘｉａ’ｓｅｃｏｎｏｍｙａｎｄｐｏｌｉｔｉｃｓ,ｂｕｔｉｔａｌｓｏｂｒｉｎｇｓｇｒｅａｔｓｏｒｒｏｗｔｏｔｈｅｐｅｏｐｌｅｉｎｔｈｉｓｒｅｇｉｏｎｂｅｃａｕｓｅｔｈｅｒａｐｉｄｓｉｌｔａｔｉｏｎｏｆｔｈｅｃｈａｎｎｅｌｂｒｉｎｇｓａｂｏｕｔｓｅｒｉｏｕｓｐｒｏｂｌｅｍｓｆｏｒｆ…     

ON THE FILTRATION OF NON-NEWTONIAN FLUID IN POROUS MEDIA WITH A MULTIPLE PARAMETER MODEL

ＮＯＭＥＮＣＬＡＴＵＲＥＡＥｍｐｉｒｉｃａｌｃｏｅｆｆｉｃｉｅｎｔ ,ｋｇ/ (ｓｍ)ＢＥｍｐｉｒｉｃａｌｃｏｅｆｆｉｃｉｅｎｔ ,ｋｇｓｎ - 2 /ｍＣａｎｄＣ1ＩｎｔｅｇｒａｌｃｏｎｓｔａｎｔＣｔＴｏｔａｌｃｏｍｐｒｅｓｓｉｂｉｌｉｔｙ ,1/ＰａＣρＣｏｍｐｒｅｓｓｉｂｉｌｉｔｙｏｆｆｌｕｉｄ ,1/ＰａＣｒＣｏｍｐｒｅｓｓｉｂｉｌｉｔｙｏｆｒｏｃｋ ,1/ＰａｇＴｈｅｇｒａｖｉｔａｔｉｏｎａｌａｃｃｅｌｅｒａｔｉｏｎ ,ｍ/ｓ2ｈｅｆｆｅｃｔｉｖｅｔｈｉｃｋｎｅｓｓ ,ｍＨＣｏｎｓｉｓｔｅｎｃｙｏｆｐｏｗｅｒ ｌａｗｆ…     

A NUMERICAL PRESSURE TRANSIENT MODEL FOR MULTILAYERED GAS RESERVOIRS WITH PSEUDOSTEADY STATE FORMATION CROSSFLOW

ＮＯＭＥＮＣＬＡＴＵＲＥＡＤｊ=Ａｊ·ｒ2 ｗ(ｋｈ) ｔＣＤｅ =ＴＶｗ2πＴｗｒｗ2 (ｈ) ｔｒＤ =ｒｒｗｐＤｊ=2π(ｋｈ) ｔＴｓｃｐｓｃｑｓｃＴ (Ｐμｚ) ｊ(φ0 - φｊ)ＴａＤ =(ｋｈ) ｔｔａ(ｈ) ｔ(μＣｇ) 0 ｒｗ2ｑＤｊ=ｑｊｑＷＤｊ=(ｋｈ) ｊ(ｋｈ) ｔωｊ=(     

A NON-UNIFORM SEDIMENT TRANSPORT MODEL WITH THE BOUNDARY-FITTING ORTHOGONAL COORDINATE SYSTEM

1. INTRODUCTIONSome problems have to be considered in the mathematical modeling for river engineering. The riverbed is always in the manner of deposition and erosion. The sediment transport is often in the state of non-equilibrium. General, the compositio…     

A MODEL FOR FIXED ALGAE MANAGEMENT IN OPEN CHANNELS USING FLUSHING FLOWS

The management of regulated rivers and canals involves new objectives of water quality preservation. Among water quality aspects, the development of benthic algae induces impacts on both the quantitative and the qualitative management. In open‐channel networks, their growth causes accumulation of biomass on the substratum, which decreases the hydraulic performance. Their detachment induces increases of drift biomass and particles likely to cause clogging issues. To manage these benthic algae developments, we study an original strategy that consists of performing hydraulic flushes in order to detach a part of the algal cover. The principle is to create a controlled hydrodynamic perturbation thanks to hydraulic control structures and to limit the quantity of fixed and drift algae simultaneously. We propose a comprehensive model of the flushes based on coupled hydrodynamic and algae detachment models in order to analyse and improve the management procedure. This model was applied on two real canals located in southern France. Copyright © 2011 John Wiley & Sons, Ltd.     

KALMAN FILTERING CORRECTION IN REAL-TIME FORECASTING WITH HYDRODYNAMIC MODEL

Accurate and reliable flood forecast is crucial for efficient real-time river management, including flood control, flood warning, reservoir operation and river regulation. In order to improve the estimate of the initial state of the forecasting system and to reduce the errors in the forecast period a data assimilation procedure was often need. The Kalman filter was proven to be an efficient method to adjust real-time flood series and improve the initial conditions before the forecast. A new model integrating the hydraulic model with the Kalman filter for real-time correction of flood forecast was developed and applied in the Three Gorges interzone of the Yangtze River. The method was calibrated and verified against the observed flood stage and discharge during Three Gorges Dam construction periods （2004）. The results demonstrate that the new model incorporates an accurate and fast updating technique can improve the reliability of the flood forecast.     

A NEW WELL TEST MODEL FOR STRESS-SENSITIVE AND RADIALLY HETEROGENEOUS DUAL-POROSITY RESERVOIRS WITH NON-UNIFORM THICKNESSES

This article presents a new well test model for stress-sensitive composite dual-porosity reservoirs based on the concept of permeability modulus, where the rock and fluid properties as well as the formation thickness vary in the radial direction. An analytical solution in the Laplace space for the pressure-transient behavior for a line-source, constant-rate well of this type of reservoir is obtained with the Laplace transformation and the perturbation technique. The pressure and its derivative in the reserv...     

A LATTICE BOLTZMANN MODELING FOR THE WESTERN BOUNDARY CURRENT IN A LINEAR WIND-DRIVEN QUASI-GEOSTROPHIC MODEL

1 .　INTRODUCTIONLatticeBoltzmannMethod (LBM )isanewnumericalmethodforcomputationalfluid (ChenandDoolen 1998) ,whichisdevelopedfromLat ticeGasCellularAutomaton (LGCA )inthelate80satlastcentury .LBMusesthecontinuousdistri butionfunctiontoreplacetheBooleanvariablesusedinLGCA .Asaresult ,LBMovercomesmanyshortcomingsofitsancestor ,suchasnoise ,notconformingtoGalileoinvarianceetc .HeandLuo(1997)developedLBMasaself containedsystemconstructedtheamodelwithoutconnectiontoLGCA .LBMha…