Relative Permeability Modifier Treatments on Gulf of Mexico Frac-packed and Gravel-packed Oil and Gas Wells
Abstract
Estimates of worldwide oilfield water production are as high as 300 to 400 million barrels of water per day (bwpd), while oil production is only 75 million barrels per day (bopd)1. Put in different terms: for every 1 bopd produced, our industry produces approximately 4 to 6 bwpd, and for many depleted areas of the world this oil-to-water ratio can be much higher, reaching up to 1:100. Excessive water production from oil and gas wells can cause serious reductions in well productivity and significantly increases operating expenses.
In an attempt to reduce the oil industry’s dilemma related to water production, there has recently been an increased interest in water control treatments using relative permeability modifiers (RPM). A new and unique RPM polymer is yielding significant economic benefits by increasing hydrocarbon production from treated wells.
Generally, RPMs are designed to control water production from high permeability streaks or due to coning issues. The polymer adheres to formation rock exposing its hydrophilic (water-loving) side to the pore throats. The RPM restricts water movement through the pore throat by reducing the effective size of the throat in the presence of water and by increasing drag on formation water flowing through the reservoir matrix. Because it deforms in the presence of hydrocarbons, the RPM typically does not adversely effect oil or gas flow. The newly developed RPM (along with careful selection of well candidates, correct treatment design, and proper placement) is helping increase the success of RPM treatments.
This paper will discuss the application and economic benefits from using the new low-risk RPM polymer. Multi-well RPM matrix treatments were performed on offshore Gulf of Mexico (GoM) frac-packed and gravel-packed wells. One particular RPM treated gas well showed a significant decrease in water production, a five fold increase in gas production and double the amount of oil. Payout for the entire treatment was just 7 days.
Introduction
Oil and gas well profitability is often compromised by excessive water production. Decreased well productivity and increased operating expenses are among the inherent problems associated with excessive water production. In addition, environmental concerns and local/federal regulatory agencies are making disposal of produced water increasingly difficult. The cost of handling produced water ranges from less than $0.10 to more than $4 per barrel of water produced, costing the industry billions of dollars per year.
Mature field development is driving the need for effective water management technologies in our industry, especially as marginal fields become more common and environmental regulations become more stringent. Numerous methods and attempts have been made over the years to control water production; however the difficulty begins with understanding the source of the water (i.e., channels behind casing, casing leaks, coning, encroachment, water breakthrough, natural or induced fractures, or high perm streaks). If the water source can be easily identified, then mechanical intervention (such as bridge plugs and/or various cement system solutions) can often be successfully implemented.
Other options include the use of various products such as polymer blocking, silicate and phenol-formaldehyde gels but each of these methods must be applied only after the water source is identified. Then, the problem zone needs to be isolated to prevent the unintentional placement of the blocking/damaging chemicals into the hydrocarbon producing sections of the zone. Herein lies the crux of the problem, locating the water source can be costly, time-consuming and, at times can even include guesswork in diagnosing the water source and/or water-producing pathway. If the water source diagnosis is incorrect and a subsequent treatment is misapplied to the hydrocarbon interval, the effects on production can be devastating.
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