Increase of certainty of calculation of hydrocarbon reserves on the basis of fuzzy petrophysical compositions method

Kobrunov, Aleksandr Ivanovich (Ukhta State Technical U) | Kuleshov, Vladislav Evgenievich (Ukhta State Technical U) | Mogutov, Aleksandr Sergeevich (Ukhta State Technical U)




The problem of parameter assessment characterizing oil-and-gas content, and its adequacy to real data which the geologist interpreter has is considered.

The necessity to appeal to this problem is connected with the existing methods of finding such parameters don't consider:

1. the real character of geological-geophysical data and the specific errors arising at parameter assessment  of  oil-and-gas content and forecasting of their values;

2. the uncertainty of conclusions concerning all parameters including volumetric data of hydrocarbon reserves on the field.


One of the main tasks of oil-and-gas field geology is calculation of hydrocarbon reserves which is nowadays carried out on the basis of three-dimensional geological-geophysical models. One of the key parameters influencing accuracy of reserve calculation is an authentic definition of factors of porosity and oil content which are calculated by means of field and geophysical methods of research. The last methods don't allow establishing the size of porosity and oil content but they estimate the sizes of geophysical parameters which are connected by correlation dependences with collector properties of breeds. To find the concrete expressions of these dependences and their parameters we use statistical data processing and finally we sometimes use replacement of the real experimental material with the received laws and some integrated assessment of Correlation ratio measure, i.e. the general for all dependence as a whole. According to the accepted technology the found law in the form of the coupling equations between parameters is transferred on the studied object. This way is often the source of erroneous conclusions which can bring: from incorrectly chosen conditions of opening and modes of well operation to mistakes in drill site and the conclusions about reserves and resources of hydrocarbon raw materials in the regions.

Nowadays at constructing 3D geological- geophysical models program products IRAP RMS (ROXAR) and Petrel (Schlumberger) are widely used. They have modular systems of construction. IRAP RMS, Petrel solve practically all problems at creation geological-geophysical models. However, these tasks are solved on the already processed information which is not always objective. As a result the constructed models don't allow solving issues of certainty of reserve calculation.