f Detection and Utilization of Volatile Organic Compounds in Drill Cutting Samples Prior to Well Testing and Completion: A Preliminary Study

Prior to well testing and completion efforts; detection of hydrocarbon rich reservoir (HRR) intervals, vertical continuity between HHR intervals, hydrocarbon types (normal oil, heavy oil, natural gas, condensate, solid bitumen etc.,) and quality (API gravity, occurrence of biodegradation) which have long been done with assessment of well log, core sample and drill stem tests. These operations, however, if the number of HRR intervals is greater than 1-2 (sometimes, HRR number>10) are very expensive particularly in offshore basins such as in Gulf of Mexico Basin in U.S.A., South Caspian Basin in Azerbaijan and Bohai Bay Basin in China and in onshore basins such as in Gediz Graben Basin in Turkey etc. For this reason, a reduction of the expenses made prior to well testing and completion was planned and parallel to the purpose, volatile organic compound (VOC) and semi-VOC (SVOCs) present in the drill cuttings were thought to be useful. In this study a total of 329 drill cutting samples were collected along the Sarıkız-2 (for every 15 m.) and -3 oil (for every 3m.) wells drilled in Alasehir, Gediz Graben of western Turkey. These cutting samples were then subjected to passive treatment with GORE™ Modules that use unique adsorbents to adsorb VOC and SVOCs in the range of C2 to C20. GORE™ modules were analyzed by thermal destruction/gas chromatography/mass spectrometry (TD/GC/MS) to detect over 45 VOC and SVOCs in a ng (10-9 g) level. An assessment of the GORE™ data (329 samples x 45 variable) with both conventional and statistical methods gave the following preliminary however encouraging results: 1) Detection of HRR intervals is possible, 2) For well testing purposes, HRR intervals can be ranked from significant to insignificant, 3) Vertical continuity between HHR intervals can be determined, 4) Seal rock efficiency can be checked, 5) Up-dip migration front can be estimated and 6) Hydrocarbon type and quality in HHRI can be approximated. Regardless of the successful results obtained in this study, the technique do not replace conventional methods yet, however do complement and enhance traditional approaches.