Oil and Gas Bearing Capacity Prognosis
Development of Hydrogeochemical Method for Separate Prognosis of Oil and Gas Bearing Capacity by Polyarenes with Fine-Structure Luminescent Spectroscopy by the First Borehole
Tech Area / Field
- OBS-GEO/Geology/Other Basic Sciences
- CHE-ANL/Analytical Chemistry/Chemistry
- INF-SOF/Software/Information and Communications
3 Approved without Funding
Russian State University of Oil and Gas, Russia, Moscow
- VNIIEF, Russia, N. Novgorod reg., Sarov
- Université Libre de Bruxelles / Department of Earth and Environmental Sciences Sedimentology and Basin Analysis, Belgium, Brussels\nLos-Alamos National Laboratory / Nuclear Nonproliferation Division, USA, NM, Los-Alamos\nTechnical University of Denmark / Institute of Environment & Resources, Denmark, Lyngby
Project summaryThe Project Objective is to develop a hydrogeochemical method for separate prognosis of deposit productivity and rejection of lacking in prospects horizons by polyarene composition and distribution in underground water samples from the first borehole by fine-structure luminescent spectroscopy (T=77K) with automated hardware-software system.
Geological survey (GS) is still a very costly activity worldwide. Geological prospecting, i.e. study of geological structures and finding of formations that may contain hydrocarbons, accounts for major portion of the expenses. As it appears on practice only 30% of such formations are productive while 70% are bored in vein. One has to bore three to five holes to evaluate productivity of a structure that is very expensive because exploration borehole depth is 4.5 km currently in Russia. Cost of such borehole researches is more than US$ 2,000,000. It depends on geological technical conditions.
The futile boring was always a reason for geologists to search for additional reliable information.
Development of hydrogeochemical technologies enables to reduce considerably the boring costs and to improve GS efficacy. Hydrogeochemical researches in Russia have been developed during more than 70 years. Different types of chemical surveys have been created during these years. The productivity assessment has been made by gas-bearing capacity of stratum water, by content of carbonate and sulfate ions in the water, by content of dissolved organic substance (OS) of underground waters (by benzene and toluene that are aromatic compounds). However, there was no a determined assessment of formation productivity. So, as a rule, the non-productive formation has continued to be bored. The problem of productivity assessment of formation was very difficult since in underground water OS all organic compounds are present in small amounts.
Hydrogeochemical technologies are most successfully applied at two major steps of the GS for oil and gas. The first stage is preparation of the structures for boring. At this step hydrogeochemical survey is carried out to assess productivity of detected structures and to determine hole boring sites.
The second step at which hydrogeochemical technologies are used is the stage of deep boring to assess productivity of the cross section and to find oil/gas-bearing objects. Efficacy of such work has been determined by long-term explorations.
During last 20 years workers of the I.M. Gubkin Memorial Oil and Gas University of Russian Federation (RGUNG) have been developing the hydrogeochemical method for productivity assessment within the local structures by polyarene composition and distribution in underground water OS with E.V.Shpol’sky’s effect of luminescent spectral analysis under low temperatures which was invented in 1953.
Low temperature ensures the appearance of narrow lines in luminescent spectra with the help of which the detection of many aromatic compounds from benzene with one aromatic ring up to rubicene with seven rings is possible.
After staying for a long time in contact with hydrocarbons underground waters dissolves and inherits monoaromatic, bi-aromatic and polyaromatic compounds. Underground water is of great information value for geology. The presence of above-mentioned compounds in underground water samples enables to make a conclusion about oil/gas-bearing capacity of a structure, their absence enables to reject it as lacking in prospects one for further boring.
The use of a device such as a spectrophotometer with a chamber for liquid nitrogen that replaced a chemical technique of analysis ensures detection of a broad set aromatic compounds (up to 32 compounds) in one sample of underground water simultaneously and determination of a polyarene complex as a universal indicator of oil/gas-bearing capacity of new generation for different oil/gas-bearing provinces.
So the original hydrogeochemical technology used by the I.M. Gubkin Memorial Oil and Gas University represents the information about composition and distribution of mono-aromatic, bi-aromatic and polyaromatic compounds in underground water OS. This technology ensures conclusions about expected carbonate type (oil, condensate, gas) or about lacking in prospects depositions.
Such technology has many advantages, such as: it is a rapid procedure (spectrum recording takes 1 to 2 minutes); it has high sensitivity of analyzed substance (10-8 mg/ml) and selectivity (detection of every compound in a complex organic mixture is possible).
The developed hydrogeochemical method is multifunctional one since it may be used in different applications:
- ecology (control of content of carcinogen and mutagen compounds);
- chemical industry (control of admixtures in liquid mediums);
- medicine (control of admixture quantities in medicines);
- electronic industry (control of water quality for chip flushing);
- food industry (product quality control of carcinogen compound presence).
Besides this method can be applied for development of further perspective directions:
- protection of underground desalinated waters from pollution of toxic substances of I and II (polyarenes);
- identification of waters of small salinity in oil and gas deposits (meteogenic and condensate ones).
The prognosis assessments of expected carbonate type from a determined productive horizon and the rejection of unproductive horizons within local structures of studied oil/gas-bearing provinces such as fore-Carpathian oil/gas-bearing region (OGBR) and Dnieper-Pripyatsk OGBR were confirmed by repeated boring. The results of hole boring demonstrated 95% coincidence with the prognosis conclusions.
Prognosis conclusions about oil/gas-bearing of productive horizons within local structures for above-listed oil/gas-bearing provinces are of fundamental importance since deep underground waters are often characterized by small salinity (according to V.V.Kolodiy). The geochemical technology of range classification for separate prognosis of productive horizons within local structures ensures analysis of deep waters of small salinity. It is a great advantage of the proposed method. In practice the GS control is possible at all GS stages from exploration to exploitation.
Within the Project framework an automated hardware-software complex is proposed to be developed. This complex consists of a spectrophotometer, a personal computer, a connection interface of the spectrophotometer with the personal computer and also a server of database (DB) with INTERNET exit for gathering information. Math software will input analysis data into computer through local networks, process and represent results of measurements, output required information in different forms through local networks, create a computer information data bank.
Testing of the automated hardware-software system will be carried out with different samples of underground waters obtained from different oil/gas-bearing provinces of Russian Federation or provided by foreign collaborators.
To achieve the Project objectives it is necessary to solve the following tasks:
- Fundamental analyses of composition and distribution of polyarene broad set as hydrogeochemical indicators in underground water OS of different well-studied OGBP.
- Detail analysis of specific composition and distribution of polyarenes in the samples of underground water OS from boreholes within local structures of OGBP for determination of a universal complex of a hydrogeochemical indicator of new generation, development math software and DB.
- Development of the algorithms for prognosis of oil and condensate hydrocarbon deposits by composition and distribution of polyarenes from well-studied OGBP, development of DB and automated hardware-software system on the base of spectrophotometer.
- Development the algorithms of prognosis of gas hydrocarbon deposits and rejection of unproductive ones by composition and distribution of polyarenes of well-studied OGBP and DB creation.
- Systematization of algorithms used by hardware-software complex for the developed hydrogeochemical method for separate prognosis of deposit productivity and rejection of horizons not containing hydrocarbon accumulations within local structures of OGBP and also its verification with control samples of underground waters.
Prognosis of oil/gas-bearing and rejection of unproductive horizons within local structures by the hydrogeochemical method of range classification is possible to be carried out in any region at any GS stage using the analysis results of underground water samples from the first borehole independently on water type, degree of its metamorphization, salinity and content of acid gases. In practice the developed method may be applied not only in geology but in other areas where information about polyarene composition and distribution in liquids is needed.
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