Quantification of Carbon Dioxide Using Downhole Wireline Formation Tester Measurements

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractCarbon dioxide (CO 2 ) occurrence in hydrocarbon bearing formations presents a challenge to the valuation and subsequent prospect development of the hydrocarbons. Corrosion is a major concern effecting capital and operational expenditures since the presence of CO 2 can cause corrosion failures. Carbon dioxide also denotes an issue for health, safety and the environment (HSE) and is readily absorbed by elastomer seals, weakening the resistance of those seals and compromising the integrity of the fluid samples and the safety of equipment and personnel. The conventional procedure to evaluate the CO 2 content in a hydrocarbon bearing formation is to take fluid samples downhole or on surface during a well test and send the fluids to the laboratory for analysis. Both methods are compromised by the reactive nature of CO 2 , whose concentration can change significantly by reaction with formation waters, mud filtrates, etc. before reaching an analysis facility. Optimizing the fluid sample acquisition program to match existing fluid complexities is impossible without real-time analysis. Recently, NIR (near-infrared) spectroscopy has enabled the real time analysis of the CO 2 content in downhole fluid samples. This paper describes a new method for using DFA * (Downhole Fluid Analysis) in the real-time determination of the CO 2 amount in the MDT * (Modular Dynamic Formation Tester) flow line. Extensive laboratory data from a research grade spectrometer and shop data with the downhole tool support the new methodology. Multiple interpretation algorithms have been developed for CO 2 quantification and verified in the laboratory. Several log examples are given * Mark of Schlumberger demonstrating successful CO 2 detection and subsequent confirmation of the measured concentrations by the laboratory data.

The Colloidal Structure of Crude Oil and the Structure of Oil Reservoirs

“…For example, Lake Nios of Cameroon requires continuous venting to prevent deadly CO 2 plumes from erupting from the lake. Likewise, reservoirs close to the corresponding tectonic fault contain CO 2 …”

The Impact of Reservoir Fluid Compositional Variation and Valid Sample Acquisition on Flow Assurance Evaluation

“…For concerns regarding scale and corrosion, CO2 is very important. CO2 can be measured using DFA methods; [23][24][25] more recent DFA tools are designed to improve CO2 accuracy. [24] Of course, CO2 can affect corresponding water pH, and this too can be measured downhole.…”

Sensing element for the formation fluid refractometer on the basis of total internal reflection

“…Как жидкие углеводороды, так и вода, фильтрат бурового раствора обладает рядом характерных признаков в оптическом диапазоне, проявляющихся в спектральных зависимостях поглощения оптического излучения, значениях показателя преломления, уровне рассеяния, флуоресценции [1]. Анализируя взаимные соотношения перечисленных характеристик, можно получить исчерпывающую информацию о качественном и количественном составе флюида [2][3][4][5][6], что необходимо для задач автоматизации и организации работ по разработке нефтяных и газовых скважин [7]. Для полноты получаемой информации используют комплекс оптических приборов -спектрометры, флуориметры и рефрактометры.…”