Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Earth science
Reexamination Certificate
2000-09-20
2002-12-24
McElheny, Jr., Donald E. (Department: 2862)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Earth science
Reexamination Certificate
active
06498988
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to hydrocarbon (petroleum and natural gas) production from wells drilled in the earth, and, more particularly, the centralized processing of oilfield or waterfield engineering data for the design and analysis of procedures associated with such drilling and production from distributed locations.
2. Description of the Related Art
Hydrocarbon production typically involves drilling a well through the earth's subsurface to a hydrocarbon deposit and then extracting the hydrocarbons. Drilling a well in the subsurface is expensive, which limits the number of wells that can be economically drilled. Also, even the most skilled and talented people using the most sophisticated tools and techniques will occasionally drill “dry holes,” i.e., wells that do not produce. The relatively high expense, the limited number of wells, and the occasional failures drive producers to more quickly, accurately, and efficiently locate, and extract hydrocarbon deposits. Producers have consequently developed an extensive body of technology surrounding the location and production of hydrocarbons. Different parts of this technology deal with, for example, measuring physical and/or electrical characteristics of geological formations, facilitating the drilling of bore holes, and stimulating production. Typically, these areas of the technology intersect.
Consider, for instance, a production stimulation technique known as “fracturing.” The rate of flow, or “production” of hydrocarbon from a geologic formation depends on numerous factors. One factor is the radius of the bore hole. As the radius of the bore hole increases, the production rate increases, everything else being equal. Another factor, related to the first, is the flowpaths available to the migrating hydrocarbon. The expense of drilling a well only generally increases as the size of the hole increases. However, a larger hole imparts greater instability to the geologic formation. This increased instability increases the chances that the formation will shift, and therefore damage the well bore or, at worst, collapse the well bore. So, while a larger bore hole will, in theory, increase hydrocarbon production, it is impractical and carries a significant downside. Yet, a fracture or large crack within the producing zone of the geologic formation, originating at and radiating from the well bore, can actually increase the “effective” (as opposed to “actual”) well bore radius. The well then behaves (in terms of production rate) as if the entire well bore radius were much larger.
Such a fracture can be intentionally created to stimulate production, and this technique is known as fracturing. Hydraulic fracturing involves literally breaking or fracturing a portion of the surrounding strata, by injecting a specialized fluid into the well bore directed at the face of the geologic formation at pressures sufficient to initiate and/or extend a fracture in the formation. More particularly, a fluid is injected through a well bore. The fluid exits through perforations in the well casing and is directed against the face of the formation at a pressure and flow rate sufficient to overcome the in situ stress (a.k.a. the “minimum principal stress”) and to initiate and/or extend a fracture(s) into the formation. Actually, what is created by this process is not always a single fracture, but a fracture zone, i.e., a zone having multiple fractures, or cracks in the formation, through which hydrocarbon can more readily flow to the well bore.
In practice, fracturing a well is a highly complex operation performed with the complex orchestration of over a dozen large trucks, roughly the same number of highly skilled engineers or technicians, a mobile laboratory for real-time quality assurance, and powerful integrated computers that monitor pumping rates, downhole pressures, etc. During a typical fracturing job, over 350,000 pounds of fluid will be pumped at extraordinarily high pressures (exceeding the minimum principal stress) down a well, to a pinpoint location, often thousands of feet below the earth's surface. Moreover, during the fracturing process, constant iterations of fluid level, pumping rates, and pumping times are performed to maximize the fracture zone, and minimize the damage to the formation.
Consider also, the use of drilling fluids known as muds. A drilling fluid or “mud” is typically continuously circulated from the surface down to the bottom of a well bore being drilled and back to the surface again. The mud has several functions, one of them being to transport cuttings removed by the drill bit up to the surface where they are separated from the mud. A second function is to form a filtercake on the walls of the bore hole so as to avoid a collapse of the bore hole. However, the filtercakes formed on the bore hole walls can cause damage to the reservoir and impair productivity unless they are removed or bypassed after drilling. The process of filtercake removal in open hole wells is frequently called “mud clean up.”
The data needed to properly design well procedures, such as fracturing or mud clean up treatments is acquired by logging or other methods of measuring reservoir properties, including, but not limited to, coring, fluid sampling, or pressure testing. This data is then analyzed and used in a variety of engineering calculations to determine the best methods of completing, producing, or stimulating a particular well. The final choice of completion or stimulation method may have a large effect on the ultimate producing efficiency of the well and its economic success. During the productive life of a well or reservoir, the data may also be used to design remedial treatments or changes in production methods.
The efficient production of hydrocarbons requires constant monitoring and maintenance of the producing wells and reservoir. Proper completion procedures and equipment are needed to insure adequate contact between the well and the reservoir. Stimulation treatments may be required to improve productivity from or infectivity into the reservoir for production enhancement. The design of well and reservoir treatments involves many steps, such as problem identification, appropriate treatment selection, fluid selection, placement process determination, and volume and rate calculations. Specifying mechanical equipment may also be required. After implementation, the effects of the various treatments are often analyzed to determine results and to improve future treatments. Many of the steps in design and analysis require some type of calculation to be made. The production, operations, reservoir, or service provider engineer at each field location typically performs these calculations. Frequently, the calculations involve the use of equations that are very well known in the art.
Large international companies typically have multiple field locations where such design and analyses are conducted on a routine basis. The engineers at each location may have their own method of making a particular calculation, and thus the same type of analysis may vary among the locations. For instance, an engineer at one location might perform an analysis using a software implemented analysis tool that embodies certain assumptions about the data operated on or employs a particular set of units of measurement. An engineer at a second location might perform the very same analysis using an analysis tool that embodies a second set of assumptions different from those in the first analysis tool and/or different units of measurement.
Each location or engineer may therefore have their own method of performing some particular analysis. For a large corporation, this means that many people are performing the same analysis in myriad ways. This is especially true when new products are introduced. The methodology for treatment design calculations is passed on in schools and by word or mouth within the organization. Each transmittal of the information increases the risk of misinterpretation and corruption of
Jee Virginia J.
Robert Joel A.
Weng Xiaowei
Jeffery Brigitte
McElheny Jr. Donald E.
Menes Catherine
Schlumberger Technology Corporation
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