Towards Environmentally-Friendly Additives for Well Completion and Stimulation Operations

Abstract

The oil and petrochemical industries have unquestionably been key drivers in the development of the complex, modern world we live in. They have helped power our cities, transport our goods and provided the raw materials for the development of countless pharmaceuticals, dyes, plastics and consumer products. In fact, many of the advances made in general health, and in improved living standards around the world, can be traced to the wealth generated by the oil industry. However, while few recognise this contribution, many people do worry about the risks posed by the search for, and exploitation of, hydrocarbon deposits. Indeed, despite its importance, the oil industry has, to some extent, been "demon-ized" by certain groups and subjected to disproportionate criticism. However, while the industry has a generally good pollution record, when compared to other major businesses, there is no room for complacency. Oil itself is usually perceived to be the biggest acute environmental threat, due largely to the volumes involved in occasional, highly-publicised spills and their distressing effects on wildlife. On the upstream side of the supply chain, the escape of oil is still a risk but, in addition, there are many wellsite operations that involve the use of chemical additives. In common with many industrial chemicals, some of these materials are toxic and some may not biodegrade at acceptable rates. With an increasing awareness of the potential environmental impact of chemical additives, particularly in the marine environment, there is a continuing need to develop more efficient, less toxic alternatives. We have been actively pursuing this goal since the early 1990's, replacing many additives with environmentally-friendly alternatives. This has been achieved by combining our knowledge of structure-activity relationships with our knowledge of polymer, surfactant and solvent chemistry and ecotoxicology. As a result of these efforts, many potentially harmful chemicals have been removed from active service and replaced with new, field-proven and eco-friendly systems that have been tested in accordance with OSPARCOM guidelines, or their equivalents. Use of such materials offers benefits in terms of health and safety and, ultimately, potential cost reductions when disposal and waste handling charges are factored in. Use of appropriate materials can even improve job results, as witnessed by several operators, and helps to demonstrate what can be achieved when a commitment to "green" principles is made. However, it should be recognised that there are inevitable development costs in the design, testing and manufacture of new additives. Operating companies need to give due consideration to encouraging and rewarding those suppliers and service companies who, ultimately, help them comply with current and future pollution-control regulations. Introduction There can be little doubt, in the public mind, that oil represents one of the most acute threats to the environment. Its commercial exploitation involves tapping reservoirs capable of producing at the prodigious rates needed to supply worldwide consumers. Also, being a major world commodity, whose source is often far-removed from the end-user, it is transported around the globe in vast quantities. Thus, any serious accident tends to involve discharge of substantial amounts of oil. The aftermath of such events, as portrayed by the media, is particularly harrowing - oil -soaked marine mammals, pathetic sea birds, dead fish and a blackened, uninhabitable coastline. The Exxon Valdez tanker accident in Alaska in March, 1989 is one of those incidents that springs to mind or, perhaps, the deliberate release of oil into the Arabian Gulf and the systematic destruction of wellhead control equipment by retreating Iraqi forces at the end of the Gulf war. But there are many earlier instances that have caught the world's attention. The Torey Canyon and the Amoco Cadiz, were two tankers that sank in, or around, the English Channel (actually off the Brittany coast) in 1968 and 1978, respectively. The fact that they are still remembered demonstrates the long-term ability of such events to shock us when we see the appalling effects that oil can have on the environment. The Torey Canyon was carrying 120,000 tonnes of crude oil, the Amoco Cadiz, 223,000 tonnes.

Meeting the Environmental Challenges in Cementing

“…A series of ecologically sound cementing and stimulation products have been developed in this way since the 1990's, always focusing first on the biodegradation, bioaccumulation and toxicity of the substances intended for use. 3,4,5,6 The work on the recently developed PLONOR defoamer actually started in 1994 when an effort was made to get away from the use of non-biodegradable polypropylene glycol and silicone-based defoamers and to concentrate on the vegetable oil type of raw materials.…”

The Effect of Weighting Materials on Oil-Well Cement Properties While Drilling Deep Wells

“…Barite (BaSO 4 ), ilmenite (FeTiO 3 ), and hematite (Fe 2 O 3 ) are the most commonly used weighting materials for cement [6][7][8]. In spite of its low cost, barite is rarely used as a weighting material for oil-well cement [9] because of its pollution potential, since it contains a considerable concentration of toxic heavy metals [10]. The typical particle size of barite is similar to Class G oil-well cement.…”

“…The barite used as a weighting material for cement must have a specific gravity of about 4.2 g/cm 3 to meet the API specifications. Ilmenite has a lower concentration of heavy toxic metals compared to barite [10], and its particles are very coarse compared to barite, which means an increase in the abrasion effect on the drilling system [11]. However, the use of micronized ilmenite as a weighting material for the drilling fluids has been recently suggested, which resulted in an improvement in drilling fluids rheology [12][13][14] and a reduction in the abrasive effect on drilling system equipment [11].…”

Novel Eco-friendly Additives for Aqueous and Non-aqueous Fluid Design

“…Industry funded past and present research conducted by various organizations also highlighting the need of development of green chemicals and additives for designing high performance drilling and completion fluids, loss control slurry, fracturing and stimulation fluids, etc. [1][2][3][4].…”