Abstract
Multistage fracturing technique has considerably improved gas production from tight gas reservoirs all over the world. Well production is one of the main determining factors to assess the success of a fracturing treatment. In this paper, numerous vertical and horizontal wells drilled in the high pressure high temperature heterogeneous reservoirs have been evaluated to confirm effectiveness of stimulation treatments and benefits derived from the use of novel technologies. Among many variables that were analyzed include drilling, completion, and stimulation parameters such as well azimuth, completion types, fluid characteristics, acid strength, etc.
A database for stimulated wells was created and various parameters have been grouped and assessed to provide correlation and understand the effectiveness of fracture treatments and optimize development plan. Correlations were drawn using the Pearson correlation coefficient equation to compute data trend and ensure good quality data. Numerous, very useful plots are constructed and presented that show the different trends of the variables evaluated and how they affect production rate.
Analyses results indicate that use of real-time geomechanics is important to predict reservoir pressure and mud weight as wells are laterally drilled in the preferred minimum in-situ stress (σmin) direction. This is because when wells are drilled along σmin, they tend to become more unstable due to the higher stress acting on the wellbore. Accuracy in predicting stresses and pressures are keys to the drilling of such wells. The completion assemblies were selected between open hole multistage and plug and perforation cased hole approaches based of reservoir properties and hole conditions. The impact on production performance by using of non-damaging low gel loading fracturing fluids, high strength proppants, and optimal fluid and acid volumes have been demonstrated using actual field examples. The paper also illustrates the use of novel fracturing approach such as channel fracturing and its impact on sustained gas production in tight gas and making low productivity wells commercial.
