Upon initial completion, a good number of wells (vertical or horizontal nor inclined) typically do not produce at expected flowrates. To remedy the situation, an effective re-completion design is needed that can address the various components of wellbore total skin associated with faulty and/or inadequate completion. Important components of total skin include mechanical skin (wellbore damage), partial completion and ineffective perforation or gravel pack. Reduced well production due to partial completion will not be remedied by an effective acid job. Also, by increasing the perforation interval, one may not be able to remedy problems associated with wellbore damage.
In this paper we present a technique that can allow one to differentiate between the various components of wellbore total skin and thus provide the opportunity to design an effective and optimized re-completion design. The technique involves integration of petrophysical log and well test derived permeability with either production or injection profile data. The paper concludes with a field case study to illustrate the application of the technique.
Following initial completion, a good majority of wells typically do not produce at expected potential flowrate. Such a problem can be associated with all types of wells—vertical, horizontal and inclined. Reduced well production behavior can often be related to inadequate completion. Effective re-completion design recommendations require the identification of specific reasons for such reduced production. Aside the absence of energy, production decline can be due to a number of reasons. Among the important ones include, low formation permeability, partial completion (not enough perforation or gravel packed interval), ineffective completion, formation damage or a combination of any of these factories. Often, lack of formation evaluation data can result into inadequate completion. Nevertheless, correction of the faulty completion and/or inadequate completion will require necessary information regarding the formation as well as the effectiveness of the present completion. Derivation of all these parameters is complicated at best. Careful evaluation for re- completion requires the knowledge of more variable than is required for initial completion. Apart from the traditional dynamic formation evaluation parameters like permeability, mechanical skin (wellbore damage) and pressure; one also needs to address the various components of the wellbore total skin. Important components of the initial completion wellbore skin constitutes of mechanical skin, partial completion and ineffective completion (ineffective perforations or gravel pack).