Successful Use of a Cost-Effective Temporary Non damaging Gel Plug System to Isolate a Highly Permeable Producing Zone During a Stimulation Job of a Low- Permeability Gas-Producing Zone in Khuff Gas Reservoir in Bahrain–A Case History

摘要

In recent decades Bahrain has experienced a rapid growth ingas demand for industrial use, electricity generation, gasinjection, and artificial lift. The main source of gas for theseneeds is the Khuff reservoir. The Khuff gas is currently beingproduced from 29 prolific gas wells.To enhance the productivity of the Khuff reservoir a matrixacid stimulation program was undertaken using coiled tubingand a temporary non damaging gel plug system with completeregained permeability to isolate the high-permeabilityproducing zone while the low-permeability gas-producingzone was being stimulated. Because the isolated zone is alsoproducing, the gel system has to be completely non damagingwith full regained permeability to this isolated formation.The success of stimulating a low-permeability intervalwhere a high-permeability producing zone is also present isprimarily dependent on the ability to divert the respectivestimulation fluid into the zone of lower permeability andproductivity. Several methods are commonly used to divert thestimulating fluid in the non productive zone. These methodsare dependent on the type of stimulation and configuration ofthe completion.If coiled tubing is used for through-tubing stimulation incased holes, inflatable packers are normally considered forisolation. However, inflatable packers have limited expansionratios and pressure capabilities. The previous use of ballsealers gave very limited results of only 10% incrementalgas production.This paper will present the successful stimulationtechniques and results of a unique and cost effective solutionfor a well where two intervals with different permeabilitieswere isolated without the high risks and costs of using a mechanical packer. Coiled tubing was used to stimulate thelower interval while the upper producing interval was isolatedusing a temporary chemical packer. Temperature in this wellexceeded 270°F.