Combating Production Loss Due to Paraffin Deposition: A Success Story ofThermochemical Stimulation in Western India

摘要

Wax deposition during production and transport of paraffinic crude is one of the serious problems facedin downhole and surface operations. Crude oil often contains paraffins which precipitate and adhere to theliner, tubing, sucker rods and surface equipment as the temperature of the producing stream decreases inthe normal course of production. Conventional methods of removal of paraffin deposits include chemicaldissolution, hot oil/water circulation, mechanical scrapping and pigging. As an alternate to the conventionalmethods of paraffin removal, wax removal by exothermic chemical reaction also known as thermochemicalstimulation is the technique in which the energy liberated from a suitable exothermic reaction is utilizedfor melting the paraffin deposits and has been shown to be more effective than the conventional treatmentsin literature. A major challenge faced while execution of this technique is to control the reaction rate and providesufficient delay time so that heating can be targeted to the desired depth of paraffin deposits without affectingthe integrity of well completion equipment. Towards achieving this goal, this paper describes the key aspectsof job design and execution that may significantly enhance the success of exothermic stimulation in wellssusceptible to paraffin/organic deposition. The challenges encountered and respective solutions executedare presented through a case study of implementation in 5 onshore wells of western India. The paper alsopresents a lab validated mathematical model that may be used to predict the behavior of the exothermicformulation and help in optimization and quality control. The job execution procedure including solutionpreparation, quality testing, pumping, placement and monitoring has been streamlined from field experienceto develop a standard operating procedure that may be referred for an effective implementation of thistechnique.