Positive displacement gear flowmeters and Coriolis mass flowmeters are typically used in this service. However, positive displacement gear flowmeters with 0.3% of rate accuracy are typically more accurate than Coriolis mass flowmeters after Coriolis mass flowmeter pressure drop, zero stability and actual flow rates are considered.

Drilling rig safety and productivity can be significantly enhanced by installing flowmeters to measure drilling mud and related flow streams.

Chemical injection feed rates are traditionally maintained at fixed values until operating conditions warrant change. Therefore, the process control objective of maintaining the desired mass concentration of each injection chemical at each strategic location is compromised because the production flow can vary during operation. Installing a production mass flow measurement and associated controls can enable the control system to automatically ratio the injection chemical flows to the production mass flow to better address the control objective. The chemical and economic savings associated with full implantation can be substantial.

Superior control strategies and more accurate control of chemicals injected into wells can significantly improve their profitability, their sustainability and better protect equipment. While savings are typically lower than those associated with installing a production mass flowmeter, they are nonetheless significant and usually worthy of implementation, especially in new chemical injection systems, and sometimes in existing systems, depending on the size and anticipated life of the well.

 Excerpted from Measuring Difficult Flow Streams and More Accurate Flow Control Can Improve Oil and Gas Well Profitability in Processing magazine.

In general, considering the overall problem holistically and combining various technologies to achieve superior results interests me. If you think about it... this is what we do every time we apply instrumentation to a process. In my mind, it was egregiously wasteful to operate a pump at full speed to generate hydraulic energy only to dissipate that hydraulic energy across a control valve --- especially when the control valve was located in plain sight at the pump discharge.

This practice was clearly wasteful, and it would be much more efficient to control flow by reducing the speed of the pump and eliminating the control valve. Predicting the actual waste involved in this practice required a working knowledge of many technologies to include electrical, instrumentation, chemical, hydraulics, pumps, energy, electrical distribution, utilities, and the like. There were no books written that analyzed each aspect of the application of variable speed drives in a practical manner. Further, my professional experience was limited to a few years, and I had not yet written any books or technical articles, nor had any teaching or expert witness experience.

Next month I will describe the road taken to show the amount of waste associated with this operation.

This article originally appeared in Flow Control magazine.

This question only begins to illustrate some of the instrument specification problems that exist in industry. All of the above specifications are well-defined, and all of these statements mean the same thing --- only the wording is different. Answers A, B, C and D are correct. 

Additional Complicating Factors

Instrumentation suppliers often specify performance in a vague manner such as “1 percent”. This type of statement begs the question, “1 percent of what?” Answers often include 1 percent of rate, span, maximum span, or other semantic variations thereof. Some telephone inquiries actually reveal that the supplier does not know the answer to the question but will check and call back. In one case, a supplier investigated, provided an answer, and later changed the answer after re-investigating.

Sometimes suppliers state instrument performance clearly but actually mean something else. This became evident when investigating non-contact level gauges where accuracy specifications were expressed over 25 different ways by the different suppliers.

This article originally appeared in Flow Control magazine.