oa Enhanced assessment of naturally occurring tarmat in hydrocarbon reservoirs using a new laser-induced pyrolysis system

Stakes: Tarmat is a dark brown to black, thick, semisolid to viscous mixture of heavy hydrocarbons (bitumen) enriched in asphaltenes, that occurs naturally in hydrocarbon reservoirs. Tarmat has impact on reservoir connectivity, on petrophysical properties, on electrical logs, on hydrocarbon reserves calculation and on water flooding. Estimating the amount and the distribution of tarmat in reservoirs is key to a proper assessment of the viability of and oil and/or gas field development. Objective: Acquire quantitative and high resolution (centimetric or sub-centimetric)measurements of the organic carbon present in a core, at the laboratory or at the coring site, using a new pyrolysis instrument developed by Total (LIPS: "Laser Induced Pyrolysis System". Principle: The LIPS consists in 4 main parts: 1/ A bench for core examination and for acquiring the X,Y,Z coordinates of the laser impact on the core surface, 2/ A core Box Storage Unit (CBSU), allowing to store up to 30 core boxes, 3/ A core Box Sampler, used to carry the core boxes from CBSU to Acquisition Unit and vice-versa, 4/ An cquisition Unit, including a laser gun, several detector(s), a mechanism for moving the laser head and a device for extracting organic vapors. Results: on the contrary to conventional methods, not always satisfactory in tarmat detection, the LIPS provide the following: o A high resolution log of the % of bitumen in the porosity, o The precise location of permeability barriers in reservoirs. o The detection of huge variations and heterogeneities of the bitumen content within the rock porosity. o A better representativeness of the vertical and lateral tarmat distribution in the geological formation. In addition, the high resolution provides a better correlation between tarmat occurrence and lithology, rock type and petrophysics, allowing better models for tarmat occurrence in Oil and Gas reservoirs. Initially developed for petroleum applications, the LIPS could be used for other applications (e.g. mapping of trace amounts of organic material on solid objects).