RIASSUNTO
Abstract
Worldwide demand for energy has forced the energy services industry to increase process efficiency and create innovative new methods of fracture stimulation optimization. Pinpoint fracturing methods represent a divergence from conventional fracture stimulation methods, which provide minimal optimization to reservoir volume. Pinpoint fracturing methods allow multiple interval completions to be performed efficiently, helping ensure that all intervals receive the optimum fracture intensity.
To increase process efficiency, coiled tubing (CT) is used to hydra-jet perforate intervals for individual fracturing treatments at predetermined depths. The process uses a unique bottomhole assembly (BHA), which was recently redesigned to increase the efficiency of the hydra-jetting tool and isolate the fracture stimulation from previous intervals. This pinpoint fracturing method does not require removing the CT from the well between treatments. Risks of non-productive time (NPT) are mitigated because contingencies for early screenout avoidance can be initiated immediately during the fracture stimulation with minimal impact on overall completion costs. Treating intervals individually substantially helps reduce the amount of hydraulic horsepower required onsite, further reducing completion costs and the risk of NPT caused by down horsepower.
Re-innovating fracture stimulation technology is often a challenge. The new technology must add value and efficiency to the process, while remaining reliable and commercially viable. In this case, these requirements were met by reducing the complexity of the BHA while increasing hydra-jetting efficiency. The elimination of moving parts increased the process reliability and simplified operational procedures.
This paper examines the re-innovation of this older technology.
Overview
Current Markets. To unlock unconventional oil and gas reservoirs, operators have their sights set on the shale plays in the US. Oil and gas industry trends can swing back and forth, varying with consumption and supply vs. stock market price. After having a seasonally warm winter in most parts of the world, the uncertain short-term energy outlook with current prices is trending for crude oil and natural gas. The US natural-gas working inventories have risen 41% above the previous year, causing a decline in the price of natural gas and putting the operator's focus more towards oil reservoirs. Oil prices should increase slightly over the next few months, rising on average USD 5 per barrel in 2012 (U.S. Energy Information Administration 2012).
Looking into the future and because of the cycles the industry goes through, operators focus more attention on increasing completion efficiency and reservoir drainage compared to applied completion.
Current Methods. Operators in the US generally take a factory approach to completion of wells that meet a certain net present value (NPV), as it is cheaper and often efficient. But, this does not take into account the contingency costs incurred by NPT. NPT can be contributed to by events, such as underdesigning the fracturing interval to avoid a screenout, which can cost hours to days in NPT, casing failure, stuck wireline, misfire of perforating guns, premature plug setting, or even a fishing operation. These practices do not always provide the best stimulated reservoir volume (SRV) for long-term production and elimination of the need for recompletion in the future. This, then, changes the true NPV for the economic life of the well.