Jonathan Wylde

Microemulsions as Flowback Aids for Enhanced Oil and Gas Recovery after Fracturing, Myth or Reality: A Turnkey Study to Determine the Features and Benefits

Flowback aids have been long reported in the litera ture as being beneficial to enhance clean-up after stimulation treatments, and in particular hydraulic fracturing. The goal is for the flowback aids to allow the piston like flo wback and return of fluids from the reservoir resulting in minimal losses to t he formation and no memory effect that hampers back production. Microemulsions have also been reported in the liter ature and a review (including patent landscape) cre ates somewhat of a myth around their exact mechanism of performance an d benefit to the application. The present work was concerned with the development of flowback aids based on micro-/nano-emulsion tec hnology for enhanced gas and oil recovery after fracturing appl ication. The goal was to formulate microemulsion co ncentrates which form nanoemulsions when diluted into fracturing flu ids and provide strong surface and interfacial tens ion reduction to minimize reservoir damage. Microemulsions have been formulated with various po sible surfactants and oil systems. The performance of the different formulations has been evaluated with different test me hods, adopted from literature and industry best practice in order to screen for most promising microemulsion systems and compared to their aqueous equivalents to determine the performance benefits offered by emulsified packages. High throu ghput experimentation and robotic formulation was u tilized to screen several thousand formulations from nearly 50 differ ent surfactant packages. This allowed for incredibl e synergistic properties to be discovered very quickly and efficiently. The d velopment of a new class of microemulsion package that is made up of almost 100% renewable and environmentally friendly components has made a large step change towards the sta e of the art of this class of flowback aids. Regain permeability and core flow testing was perfo rmed on the best performing microemulsion formulati ons to determine the effect of field application. The result of this work was that microemulsions do offer some benefit s over individual surfactants, not so much in surface tension modific at on but very much on the non-emulsification of cr ude oil and water and multiphase flow in porous media – so often seen as the primary damage mechanism in oil well fracturing . Introduction Hydraulic fracturing is a technique used to stimula te the production of an oil or gas well. Since Stan olind Oil & Gas Company introduced hydraulic fracturing in 1949 (Cl ark, 1949), more than 2.5 million fracture treatmen ts have been performed worldwide. Some believe that approximatel y 60% of all wells drilled today are fractured even before primary production begins. Fracture stimulation not only in creases the production rate, but it is credited wit h adding to reserves which otherwise would have been uneconomical to develop. In addition, through accelerating production, net p resent value of reserves has increased. Horizontal drilling and hyd raulic fracturing have been essential keys in econo mically producing oil and gas from unconventional resources such as shale gas, shale oil and coal bed methane.

Environmentally Acceptable Replacement of 2-Butoxyethanol with a High Performance Alternative for Fracturing Applications

This paper concerns the development and implementation of a replacement chemistry for 2-butoxyethanol used in fracturing. The new product was synthesized to provide mutual solvency, wettability modification and clay swelling inhibition. Recently, 2-butoxyethanol has come under scrutiny in North America (e.g. prompting Environment and Health Canada to add it to Schedule 1 of the Canadian Environmental Protection Act). Precautions need to be taken when working with 2-butoxyethanol due to toxicity concerns. Exposure to high levels has led to reported nose and eye irritation, headaches and vomiting. Introduction of an alternate product has had a profound effect on the stimulation market in Canada. So far, 400,000 kg of the alternative product has replaced an estimated annual usage total of 3 to 4 million kg of 2butoxyethanol. The new product also has had successful applications in the US, Latin America and Europe. There has been a significant environmental impact already realized through the use of this alternative product, and there is even greater unrealized potential. Additionally, as a non-regulated product for use and handling, the safety and material handling implications are greatly improved. This paper details the chemistry of the replacement product, as well as environmental information to support the use of this product as a benign replacement for 2-butoxyethanol. An in-depth description of the laboratory testing used to identify, evaluate and select the appropriate treatment parameters also is given. The paper concludes with two case histories from northeast Alberta where this product was successfully used as part of a fracture treatment for long, horizontal, multi-zone shale gas plays. furthermore comparisons are made using 2-butoxyethanol and no mutual solvent chemistry in a fracture treatment. This data shows the clear benefit of using this new chemistry. To order the full paper, visit http://www.onepetro.org/mslib/servlet/onepetropreview?id=SPE-141099-MS

Development, Testing, and Field Application of a Heavy-Oil Pipeline-Cleaning Chemical: A Cradle-to-Grave Case History

This paper details the complete evolution of a new cleaning chemical for heavy oil and gas pipelines. Information is offered regarding the reason for development, the research involved in formulation of the new product, as well as the laboratory testing. This paper concludes by giving several case histories of application in cleaning operations in Western United States and Texas. Oil naturally contains paraffins, asphaltenes and naphthenates. During transport these hydrocarbon components can precipitate and adhere to the pipeline walls and can become associated with iron sulfide scale. Corrosion can often occur on pipeline walls under these organic deposits. Pigging operations are normally performed to remove organic and inorganic debris from the walls of a pipeline. However, these scales can become very compacted and adhere to the walls of the pipeline. It is often necessary to add surfactant based chemicals to assist in the break-up, softening, and transportation of these deposits. A detailed literature review of the current theory in the chemistry of pipeline cleaning chemicals is presented together with a critical account of the key properties required of these chemistries: wettability alternation, solubilization efficacy of organic materials, emulsification of phases, dispersion, detergency, and defoaming. An explanation of the laboratory development and evaluation has been given as a preamble for the case histories. One case history details how a pipeline operator unsuccessfully tried to clean a 12” 9-mile section of pipeline with a pig. The pig was launched and became stuck along the length of the pipeline. Application of the newly developed product was able to free the stuck pig and removed significant debris. By way of conclusion the paper offers suggestions on how chemicals can be most efficiently used in conjunction with these programs. Introduction Pipeline Fouling Mechanisms and Typical Deposits Pipelines often saddled with internal deposits that restrict flow of the transported media, necessitating shut downs and offline cleaning programs. Many types of solids are found adhered internally in pipelines due to a wide variety of sources. The media throughput of a pipeline transports can be used to broadly characterize the type of deposits that are most commonly observed. This is a general rule only, linked with the fact that very few pipelines transport 100% of any single phase. For example, all oil export pipelines transport a small associated amount of water typically between 0.2 and 2.0% BS&W. This small amount of water can result in aqueous originated deposits even though by far the dominant phase in the pipeline is hydrocarbon based. Typically, a pipeline that transports crude oil becomes fouled with organic scale. Oil naturally contains paraffins, asphaltenes, and naphthenates. During transport in a pipeline, these can precipitate and adhere to the walls of the pipeline.

Development, Testing, and Field Application of a Heavy Oil Pipeline Cleaning Chemical: A Cradle to Grave Case History

This paper details the complete evolution of a new cleaning chemical for heavy oil and gas pipelines. Information is offered regarding the reason for development, the research involved in formulation of the new product, as well as the laboratory testing. This paper concludes by giving several case histories of application in cleaning operations in Western United States and Texas. Oil naturally contains paraffins, asphaltenes and naphthenates. During transport these hydrocarbon components can precipitate and adhere to the pipeline walls and can become associated with iron sulfide scale. Corrosion can often occur on pipeline walls under these organic deposits. Pigging operations are normally performed to remove organic and inorganic debris from the walls of a pipeline. However, these scales can become very compacted and adhere to the walls of the pipeline. It is often necessary to add surfactant based chemicals to assist in the break-up, softening, and transportation of these deposits. A detailed literature review of the current theory in the chemistry of pipeline cleaning chemicals is presented together with a critical account of the key properties required of these chemistries: wettability alternation, solubilization efficacy of organic materials, emulsification of phases, dispersion, detergency, and defoaming. An explanation of the laboratory development and evaluation has been given as a preamble for the case histories. One case history details how a pipeline operator unsuccessfully tried to clean a 12” 9-mile section of pipeline with a pig. The pig was launched and became stuck along the length of the pipeline. Application of the newly developed product was able to free the stuck pig and removed significant debris. By way of conclusion the paper offers suggestions on how chemicals can be most efficiently used in conjunction with these programs.