Sampling Gas-condensate Wells

Abstract

Of the various methods of sampling gas-condensate wells, a method thatsecures a continuous representative sample of the well stream is desirable.Such a method, consisting of a sampling tube introduced into the well tubing, has proved satisfactory. The method is sufficiently accurate for operating andengineering problems. A portable testing apparatus can be used with thesampling tube to obtain data useful in studying the economic and technicalaspects of the development and operation of gas-condensate properties. Introduction The recent discovery and development of gas reserves that containhydrocarbons that condense with reduction of temperature or pressure, or both, to form a product known as condensate, has brought many new problems to the oiland gas industries. With further discovery of deep, high-pressure fields it ispresumable that many more gas fields of this type will be added to the steadilyincreasing number. Such gas reserves are found either associated with oil as agas cap or in separate formations. There seems to be no positive correlationbetween the physical or geological nature of the reservoir, and the chemicalcomposition or phase characteristics of its contents. Knowledge of the chemical make-up and phase behavior of gas-condensatereserves is needed to cope with many problems. A knowledge of the chemicalcomposition and phase characteristics of the reservoir material is necessary toproperly design a gasoline or recycling plant, to estimate natural gas andcondensate reserves, to enable the operator to study the economic and technicalaspects of various methods of operation and development, and to carry out theplan of operating subsurface and surface lease equipment. This information isoften useful in questions of mineral ownership, proration, legal position, andtaxation. It is the purpose of this paper to discuss methods used by the writers todetermine the chemical composition and phase characteristics of the fluidsproduced from a condensate well. The scope of the paper includes a discussionand description of the method of sampling, the results of tests on the accuracyof the sampling method, a description of a portable testing apparatus used toexamine the phase characteristics, typical results of tests on wells fromseveral condensate fields, and some of the applications of these data toproduction problems. References to previous work on this subject are cited at the end of thepaper. T.P. 1374