Improving Hydrocarbon/Water Ratios in Producing Wells - An Indonesian Case History Study
Authors: Stanley Frederick O. , Hardianto _ , Marnoch Ewen , Tanggu Paternus Syukur 
Published: December 2007

Excessive water production is consistently burdening the oil industry, especially as lifting and facility costs rise and disposal of produced waterbecomes increasingly difficult, expensive and environmentally sensitive. Apreviously developed amphoteric polymer material (APM) (SPE Paper No. 14822)has been successfully applied in Indonesia. This product reduces volumes of produced water and very often increases hydrocarbon production by effectivelyreducing the permeability to water without significantly changing the formation permeability to hydrocarbons. This paper will review the mechanism, application and associated lab results by which the APM polymer reduces water cut with the primary emphasis on the Indonesian case histories and placement techniques.

Results indicate that high permeability sandstone reservoirs, with water production problems, can benefit from APM treatments. The product cansuccessfully and economically reduce water production with the added benefit of increased hydrocarbon production often noted. Laboratory and field results indicate good product application under high shear situations and at temperatures up to 275 F. Careful candidate selection and good placement techniques, in conjunction with production logging to determine water location, are important to the success of APM jobs.

Introduction

Oil company profitability is suffering in high water cut areas and a focus on methods for water control is paramount in the engineers plans to increase profits. Wells treated during the late 1995/early 19% Indonesian study showed a water cut reduction, an increased oil cut, and a reduced total volume of produced fluid in the field enabling more wells to be placed on line and not exceed water management capabilities of the production facilities.

High water cuts are often due to common oilfield phenomenons such as waterfingering, coning or early breakthrough during flooding projects. Water production occurs in many oil and gas wells primarily because of the higher mobility of water relative to hydrocarbons. This water production can take place on the initial completion or later in the life of the well. Small amounts of water may not create problems; however, when the production of water becomes excessive, consideration of water reduction is often necessary. Operators are often required to shut-in high water cut/low oil producing wells so that they can meet facility capabilities even though the reservoir is known to contain economic quantities of hydrocarbons. Large quantities of water add to the overall dollar per barrel costs of producing a well. More water can mean additional lifting, separating, and treatment costs as well as the environmental concerns that are associated with water disposal.

Hydrocarbon production can also be reduced by high water production. The increased wellbore hydrostatic head often reduces the available energy to drawdown the reservoir. Higher density water in the tubing string can lead to early shut-in or the installation of unplanned artificial lift equipment.

The relative amounts of gas, oil and water present at any particular level in the reservoir will determine the most likely fluid(s) that will be produced by a well completed at that level and will also influence the relative rates of production.

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