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Treatment evaluation leads to problem identification and to continuously improved treatments. The prime source of information on which to build an evaluation are the acid treatment report and the pressure and rate data during injection and falloff. Proper execution, quality control, and record keeping are prerequisites to the task of accurate evaluation. Evaluation of unsatisfactory treatments is essential to recommending changes in chemicals and/or treating techniques and procedures that will provide the best treatment for acidizing wells in the future. The most important measure of the treatment is the productivity of the well after treatment.
Elastomers are rubber or plastic materials used as a seal. They are commonly used in packers. There are many suitable elastomers on today's market to match almost any downhole condition. Care must be taken to ensure that the elastomer selected for the packer and seal assembly meets all the downhole conditions to which it will be subjected. There is no single best elastomer that will perform under all conditions combined, and selection must be tailored to suit individual well requirements and application.
When downhole tools that collect data were created, they stored the data in memory on the tool itself. The data were downloaded when the tool was next pulled from the hole. Communication with downhole tools while drilling is currently achieved with either mud-pulse telemetry or electromagnetic-based systems. The maximum data transmission rate (correlated with bandwidth) of these systems is about 10 bits per second. As a result, much of the information from measurement while drilling (MWD) and logging while drilling (LWD) must be processed and stored in computer memory associated with the downhole instrumentation near the drill bit.
Many oilfield processes normally employed on the surface may be adapted to downhole conditions. Examples include phase separation, pumping, and compression. Sometimes the design specifications for downhole processes may be looser than surface processing because control is more difficult. Partial processing, in which fluids are separated into a relatively pure phase stream and a residual mixed-phase stream, are most common. Downhole separation technology is best suited for removing the bulk (50 to 90%) of the gas or water, with downstream surface or subsea equipment being used to "polish" the streams for complete separation.
As with most technology, proper candidate selection is key to success. The economics are often determined by the number of and locations of the wells and by the overall geographical development plan. It is important to recognize that downhole processing is not a substitute for prudent profile control of wells through workovers, gel polymer treatments, cement squeezes, and so on. The following discussion applies to both gas/liquid and water/oil processing, followed by sections that discuss screening criteria specific to each. From an equipment standpoint, gas/liquid separation is much easier than oil/water separation. This generally means that it is a more robust application. All separation and pump equipment has an expected lifetime that is typically much shorter than the lifetime of the well. The cost of replacing or repairing the equipment must be considered as well as the initial capital cost.
DNA fingerprinting (also called DNA typing) involves isolating and creating images of DNA (deoxyribonucleic acid) sequences. In the context of reservoir characterization, DNA samples from microorganisms found living in crude oil are examined. The process for creating a DNA fingerprint consists of first obtaining a sample of cells containing, extracting the DNA from the sample, and purifying the DNA. Fragments of different lengths are produced then sorted by placing them on a gel and subjecting the gel to an electric current in a process called electrophoresis: the shorter the fragment, the more quickly it will move toward the positive pole (anode). After electrophoresis, the sorted, double-stranded DNA fragments are subjected to a blotting technique in which they are split into single strands and transferred to a nylon sheet.
The purpose of the digital oilfield is to maximize oilfield recovery, eliminate non-productive time, and increase profitability through the design and deployment of integrated workflows. Digital oilfield workflows combine business process management with advanced information technology and engineering expertise to streamline and, in many cases, automate the execution of tasks performed by cross-functional teams. The term "digital oilfield" has been used to describe a wide variety of activities, and its definitions have encompassed an equally wide variety of tools, tasks, and disciplines. All of them attempt to describe various uses of advanced software and data analysis techniques to improve the profitability of oil & gas production operations. If one maps the challenges onto the themes, it becomes clear that digital oilfields are attempting to compensate for a higher complexity and cost of operations which must be performed by fewer, less experienced employees.
In formations with over 1% carbonate, an HCl or acetic acid preflush dissolves the carbonate to prevent waste of HF acid and formation of the insoluble precipitate calcium fluoride. Calcium and sodium chloride workover brine also must be flushed away from the wellbore with HCl acid or ammonium chloride brine. Preflushes also displace and isolate incompatible formation fluids (either brine or crude oil). Higher concentrations of ammonium chloride ( 3%) are recommended where swellable smectite and mixed layer clays are present. For successful HF acidizing, more than 120 gal/ft of HF/HCl acid is usually required.
All oil fields under waterdrive, either from waterflood or a natural aquifer, eventually produce water along with oil. Even gas-cap and depletion reservoirs may produce some water. For these reasons, as well as economics, excess water production is not desirable. The material presented in this section that deals with water control technology has been abstracted from a detailed review of water problems and control technology. This review contains the references to the original literature.
You've decided that your well is a good candidate for acidizing, assessed the formation, designed the treatment, prepared the well and equipment, so now you're ready to conduct the treatment. This page describes both the process and things you should be doing during and immediately after the treatment. The main acid job should be circulated in place with HCl acid placed across the formation before the packer is set or before the bypass valve is closed. All perforations should be covered by acid before injection starts. Injection should start at a predetermined injection rate and the pressure observed to determine the condition of the wellbore.