FLUID DESIGN TO MINIMIZE INVASIVE DAMAGE IN HORIZONTAL WELLS

Formation damage is a very reservoir specific process, but extensive s tudies indicate that generalities can often be drawn with respect to c ertain types and mechanisms of damage which are more prevalent with va rious reservoir types. This paper provides a mechanistic discussion of various types of formation damage common to horizontal wells, such as fluid-fluid and rock-fluid incompatibilities, solids invasion, effect of overbalance pressure, aqueous phase trapping, chemical adsorption, wettability alteration, microbiological activity, and fines migration . these phenomena are discussed and how they specifically relate to th e following formation types: 1. Clean and dirty homogeneous sands. 2. Clean and dirty laminated sands. 3. Unconsolidated sands. 4. Fractured sands. 5. Homogeneous carbonates. 6. Fractured carbonates. 7. Vugular carbonates. Recommendations for various fluid types and procedures wh ich have experienced success in certain situations are also presented. Laboratory testing of fluids and representative core samples is highl ighted as a potential diagnostic tool to select the optimum fluids for drilling, completion, stimulation and workover treatments. Use of the se guidelines can, in many cases, narrow the choice of potential fluid s considered for use in a given lithofacies type and increase the effi ciency of the optimization process.