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A flow is observed in the pipe for the horizontal section of slotted screen completion and inflow control device (ICD) completion, and an annulus flow exists between the pipe and the borehole wall. Based on the principles of mass conservation and momentum conservation, a model for variable mass flow in an oil reservoir to simulate wellbore–annulus–reservoir state in the horizontal section of slotted screen completion and ICD completion is proposed. Consequently, based on the newly established formation transient seepage model and wellbore and annulus variable mass flow model, an accurate prediction of the production rate of a horizontal well and optimized design parameters for slotted screen completion and inflow control device (ICD) completion are achieved. The predicted flow profiles of the established model are confirmed using the simulation software from Computer Modeling Group Ltd. When external casing packers are not considered, findings show that the predicted production rates of both slotted screen completion and ICD completion, which are obtained using the variable mass flow models without annulus flow modeling, are higher than the rates obtained using the variable mass flow models with annulus flow modeling. Both models show that the pressure profile and flow profile of the borehole wall are more uniform in wellbore–annulus–reservoir in horizontal wells. The flow model for horizontal wells with annulus flow modeling should be established to improve the accuracy of the predicted production. [ABSTRACT FROM AUTHOR]

In the pipeline system for slurry, local erosion wear failure has become the main damage mechanism of pipe in the fracturing operations of oil-gas engineering. Computational Fluid Dynamics simulation is performed to determine the evolutionary process of erosion wear in tubing connector, which is the resistance of pipeline system, and a new way to predict the pipeline longevity is provided. Based on the Euler equation, solid particle concentration in the slurry and interphase momentum exchange are included in the liquid flow equations due to the influence of dense particle on slurry (slurry is a two-phase flow), and the particle trajectory was calculated in the Lagrange frame by analyzing the forces from the interaction of liquid and particle and particles impact. With the erosion damage model, the erosion rate/depth in the connector was calculated to reconstruct the mesh model of shoulder with 5 tori. Torus 1 is closest to axis while torus 5 is on the outmost wall of the connector. During the erosion event, greatest erosion and hence surface deformation occurs on tori 1 and 2, and this affects the surrounding flow and particle movement. After 10 hours of erosion, there was a dramatic drop in the maximum erosion rate, which illustrated a conservative prediction for pipeline service life if the initial erosion rate was used. An erosion experimental setup was also performed to identify the weight loss and erosion characteristic of the inner surface with erosion time of 55 hours. It was observed that the erosion simulations provided relative errors within 18% for erosion length and weight loss compared to the experimental values, and a closed form equation for the erosion rate was proposed to predict the erosion life of tubing connector. [ABSTRACT FROM AUTHOR]

On the basis of previous research, the true trajectory of horizontal oil wells with complex structures is considered in this study. A horizontal well is an assembly of a myriad of infinitesimal section lines along the well’s length. Hence, a method to calculate the true horizontal well trajectory potential in a top-closed reservoir with bottom water is achieved. Combined with the formula of pressure drop in a single-phase variable mass flow horizontal well, a new coupled semianalytical model for horizontal well productivity prediction is established. Using a well from an offshore oilfield in China as case study, productivity prediction via calculation and comparison of the horizontal well is conducted. Prediction results show that the new model is more accurate than other models considered. The established model for real 3D well trajectory potential converts the integral solution into even-number segments to avoid the defect of zero denominator when potential calculation is conducted for the self-infinitesimal scenario. In summary, the new coupled semianalytical calculation model of productivity prediction for horizontal wells is built by establishing a calculation model for the true trajectory potential of a horizontal well. This model is proven feasible through actual case calculation. The new model is refined and stable, and productivity prediction under true trajectory conditions can be obtained with the new model. Such productivity prediction reflects the real situation of oil wells and is conducive for the optimal design of well trajectory and parameters. [ABSTRACT FROM AUTHOR]

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