Search

Legacy oil production from Appalachian basin has been in a decline mode since 2013. With more than 80% of wells producing less than 15 bbl/day, there is a growing interest in economically and environmentally viable options for well stimulation treatments. Analysis of formation mineralogy and reservoir fluids along with history of well interventions indicated formation damage in many wells due precipitation of organics and a change in wettability being partially responsible for production decline rates in excess of forecasts. The development and properties of a novel cost-effective biosurfactant based well-stimulation fluid are described here along lessons learned from several field trials in wells completed in the Upper Devonian Bradford Group. This group of 74 wells, completed in siltstone and sandstone reservoirs were presenting more than 12 well failures annually across the field, which was attributed to the accumulation of organic deposits in the tubulars. Based on these cases, batch stimulation treatments using a novel fluid comprising biosurfactants were proposed and implemented field wide. The treatments effectively removed organic deposits, changed formation wettability from oil to water wet and resulted in a sustained oil production increase. Well failures were significantly reduced as a result of this program and the group of 74 wells did not have a paraffin-related well failure for 18 months. Results from this program demonstrates the efficiency of the green well stimulation fluids in mitigating formation damage, reducing organics deposition and in increasing oil production as a promising method to stimulate tight formations.

New biochemically-derived products for the removal of paraffin wax from oil wells do not require additional capex nor heat and do not utilize bacteria. They contain inactivated microbial cells, biosurfactants and biosolvents, and other components harvested as microbial byproducts that emulsify and dissolve paraffin from rock pores and from the well surfaces over wide temperature, salinity, depth, and pH ranges. Additionally, they increase oil recovery by remediating near-wellbore formation damage, reducing interfacial tension, altering rock surfaces and changing their wettability, and reducing oil viscosity. The product application is environmentally superior to well treatments using hot oil/water and aromatic solvents and is economical due to low capital and operating costs required for product synthesis. Specifically, product preparation is achieved using a modular fermentation system that is installed near the points of application. This insures highly efficient and low-cost production and logistics, as well as reducing time from generation to application which maximizes potency. With sufficient space, water, and electricity, the initial manufacture of the dispersal products can occur within a few weeks. The treatment products utilized were initially developed and tested in laboratory studies, which showed that dispersion rates of the relevant paraffin samples were comparable to those achieved with toluene. The paraffin dispersal products exhibit a very high level of efficacy and safety when deployed in the Appalachian and Permian Basins. The potency of these products has led to outstanding paraffin removal results as indicated by reduced well failures in both vertical and horizontal wells and by visual observation of sucker rods removed from the wells. In addition, tank sludge and wax deposits in pipelines can be removed through either residual product flowing from the well or through direct application. Growth of detrimental bacteria and formation of biofilms are inhibited by the product application thereby reducing corrosion risk. Specifically, details of an almost two-year 70-well study in the Appalachian Basin are reported in which no well failures were observed due to paraffin buildup and 95% of the wells exhibited an enhanced oil recovery effect during the paraffin remediation treatments. This resulted in an approximate 50% average increase in sustained production rate over baseline. Analysis of the results forecasts a substantial increase in future production, thereby significantly enhancing the value of the producing wells. Importantly, longer times between required treatments and the increased recovery rates have transformed the paraffin maintenance program into a documented revenue generator for the operator.