The pressure‐volume‐temperature behavior for both solid and molten polypropylene was determined for pressures up to 618 atmospheres. These data were measured with a newly developed compressibility device capable of obtaining precise and accurate data. Compressibilities calculated from the experimental data compared favorably to the limited existing literature data. Constants were determined for the Spencer‐Gilmore polymer equation of state for both the solid and molten material.

SynopsisEquilibrium pressure-volume-temperature behavior in both the solid and molten regions was determined for a high density ( p = 0.958 g . /~m .~) polyethylene. Data were measured with a recently developed compressibility device capable of obtaining precibe and accurate data. Residual curve treatment showed that the data were true equilibrium data. Compressibilities calculated from the data of this work compared favorably to existing data which were limited to 205°C. The present work extended the compressibility behavior to 250OC. It was also found that differences in compressibility of low and high density polyethylenes were not eliminated in the molten region, indicating that the effect of differences in morphology was not eliminated. The Spencer-Gilmore equation was fitted to the data of the present work. The internal pressure (a) term of the equatiou showed a definite relation to polymer morphology.

synopsisThe melting points of t,hree polyethylenes differing in molecular weight distribution from 47,000 to 147,000 were determined as 141OC f 0.5OC by dilatometric techniques. Sample preparation procedures were developed to ensure uniform thermal history prior to measuring length as a function of temperature in a precision dilatometer. The specific volume data were reproducible within 0.02%, reflecting the careful annealing procedure used and the extended time allowed for equilibrium to be attained.

A.dilatometer was developed for studying the compressibility of polymers in their melting range at pressures to 8500 atm and temperatures to 370OC. Temperature was controlled to fO.Ol°C and pressures were maintained and controlled by means of a hydraulic deadweight gauge system. The device was sensitive to volume changes of 1 part in 30,000.

Operators are often presented with a dilemma when installing instrumentation in a subsea well. Do they install permanent downhole gauges? If so, is there a back-up plan in the eventuality that the downhole gauge fails. In the past, when a downhole gauge on a subsea well failed, the back-up plan has either been to "fly blind" or to rely on low-accuracy measurements from subsea tree gauges or pipeline gauges (which can also fail). While tree or pipeline gauges may be adequate to determine if the well is flowing, they are rarely of sufficient accuracy and resolution to optimize production from the well. The need for high resolution, accurate pressure data is greatest in high permeability wells and in unconsolidated sandstones, where the production of sand can be catastrophic. In 2001, a solution to this problem was developed. It allows an operator to temporarily install a highly accurate pressure recording system on the well in order to perform diagnostic tests on the well bore, completion and/or reservoir. This option is available to any subsea tree equipped with an Industry Standard "Hotstab" port. Typically, subsea trees are fitted with at least one female hotstab port conforming to ISO/CD 13628–8 enabling a remotely operated vehicle (ROV) to connect instrumentation specifically designed for this application. The ROV is then used to operate the isolation valves to allow well bore communication via the hotstab port. Once pressure communication with the well bore is established, diagnostic tests may begin. The purpose of this paper is to introduce a mobile high-precision, high-accuracy pressure recorder for pressure transient testing at subsea well heads. First, the instrument and subsea tree specifications will be discussed. Then, a detailed procedure for installing this instrument on the subsea tree will be presented. Next, the issue of wellhead to bottomhole pressure conversion will be addressed. Results from field tests with the system will be presented. This new tool makes it possible to test subsea wells in which downhole gauges were not installed or where they have ceased to operate. The tool has also proven useful for pressure integrity tests when commissioning sub sea pipelines. Introduction Accurate pressure versus flow rate data is as important to an engineer concerned with optimizing well production as an altimeter is to a pilot concerned with safety.Producing a reservoir at excessive rates risks collapse of the completion due to pressure drop exceeding the strength of the formation. Producing at reduced rates results in reduced cash flow. The industry has recognized the importance of this trade-off by investing in frequent well testing. In the case of subsea wells, it is much more difficult and expensive to conduct pressure transient tests than it is from dry trees. Therefore downhole gauges are permanently installed at a cost that can exceed a million dollars per installation. However, experience has shown that the majority of these downhole gauges installations will fail, many in less than a year. When that happens, the operator has no way of knowing if he is in danger of collapsing his completion or is producing at an unnecessarily reduced rate. The high-precision subsea pressure recorder (SSPR) allows an engineer to acquire the data necessary to safely optimize well production. Subsea Pressure Recorder The subsea pressure recorder (SSPR) is a self-powered device specifically designed for the acquisition of pressure transient data in the subsea environment. The device is housed in a subsea pressure vessel approx. 6 inches in diameter and 14 inches long. The system weighs approx. 40 pounds in air, 20 pounds in water, and is designed to operate in water depths up to 10,000 ft. Integral to the pressure vessel is the ISO/CD 13628–8 male Hotstab which is internally ported to the pressure transducer. The maximum allowable working pressure of the system is limited by the Industry Standard Hotstab to 10,000 psi.