A computer program has been developed to predict gravel placement effectiveness for a specific gravel-pack design. This program was developed as the direct result of recent studies using a large-scale, transparent, deviated wellbore model.
Earlier studies have addressed the problems associated with gravel packing deviated wellbores. Each of these studies has utilized wellbore models and circulatory techniques to illustrate the placement of gravel packs. Each also proposed various solutions to maximize the packing efficiency. A mathematical model was reported in these earlier studies which related wellbore condition and fluid properties to gravel placement effectiveness for a specific gravel-pack design. This most recent work was conducted in order to determine the accuracy of that math model prediction.
The accuracy of the computer predictions was evaluated by the use of a series of test gravel packs performed with the wellbore model. Throughout the testing, fluid density, fluid viscosity, particle size, particle density and concentration, percentage of flow loss, and casing I.D. were held constant. The pump rate, screen and tailpipe size, and angle of deviation were varied.
In each test predicted to produce a complete pack, 95 to 100% of the casing volume throughout the length of the screen was packed properly.