Reducing well contamination with microbial control optimization
With an increasing number of wells sitting idle before production, it is more important than ever to optimize microbial control throughout the lifecycle of oil and gas operations. Since the price of oil began its sharp descent in June 2014, drilled but uncompleted wells (DUCs) have doubled to about 4,000. The longer a well sits idle, the higher the risk of contamination, making the microbial control program decision for drilling and completion engineers even more important.
As demand increases and more idle wells are completed and begin producing, production engineers could be faced with soured hydrocarbons and corroded assets. In addition, modeling studies have shown that uncontrolled growth of microbes, and resulting plugging through biofilm, can reduce oil and gas production rates by 50%.
The roles of completion and production engineers
What role do completion and production engineers play to help mitigate issues caused by microbial contamination? As completion engineers fracture the well, they introduce large amounts of water, proppant, and other food sources, creating an environment prime for microbial proliferation.
Often, onsite, no more than a few days before moving on to the next well, completion engineers are focused ultimately on completing the well as efficiently and cost-effectively as possible. They commonly select a quick-kill biocide, overlooking the need for microbial control near the wellbore or in the downhole environment and making the well susceptible to issues linked to uncontrolled microbial growth including souring, biofouling, and microbially influenced corrosion (MIC).
The completion engineer has one shot at getting the microbial control program right, yet oil companies often don’t know how effective the program is until the well begins producing. The quantity and quality of the hydrocarbons produced are the production engineer’s main concern. He will immediately know whether he is confronted with sour or contaminated crude or natural gas. While there may be ways to sweeten produced material and improve its quality, they are often costly and waste time.
Integrated microbial control approach
Over the years, an integrated approach to microbial control that takes the impact of the drilling and completion stages into account has proven effective in controlling the growth of microorganisms that can wreak havoc on oil and gas operations. For example, in the completion stage it is crucial to select a biocide program that will provide control in all of the phases of the hydraulic fracturing process: preparing the water for entering the well, decontaminating the well, and protecting the reservoir.
As every shale play and well is unique, it’s important to realize that there is no silver bullet when it comes to microbial control. Today, a broad portfolio of biocides, including technologies that provide a quick kill for topside treatment and others that can sustain microbial efficacy in the downhole environment, is available for the industry. Combined with technical expertise and advanced testing capabilities, an integrated microbial control program for any given application can be designed to help operators unearth oil and gas that is primed and ready to be delivered to refiners as quickly and cost-effectively as possible.
As the oil and gas operators continue to adjust to fluctuations in the market, one thing they can count on is if they implement an integrated approach to microbial control as production begins they can produce high-quality hydrocarbons at high volumes.
Ken Wunch is a technology platform leader; Christina Pampena is the marketing manager for Dow Microbial Control.