RU2263935C2 - Method for finding deposits of oil and gas - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: method includes determining oil and gas availability of area on basis of presence of deep reservoirs in earth crust, by means of deep-mode seismic reconnaissance, and marking sizeable dynamic anomalies, prediction and localization of oil channels is performed, level of activity of oil channel is performed. Prediction and localization of oil channels is performed on basis of seismic reconnaissance in 2D or 3D variant. To determine activity of oil channel at territory of outlet of channel instability of gravitation field is researched by various special observations at fixed positions and determining changes of gravitation field in time at each of these. On basis of presence of areas of increased instability of gravitation field activity of channel is estimated. After determining channel activity, search well is drilled immediately at oil channel. At areas with uncertain availability of oil and gas, observations are performed in conjunction with geo-chemical filming.

EFFECT: higher efficiency.

4 cl

Description

The invention relates to the field of the oil industry, and more specifically to a group of methods for searching for oil and gas fields and deposits.

Traditional methods for searching for oil deposits are mainly based on predicting traps of various morphogenetic types by geological or geophysical methods and drilling prepared for drilling traps deep search wells. To identify and prepare for prospecting oil drilling prospective traps, seismic exploration is most often used. In this case, the hypsometric position of the potential productive horizon is determined and drilling is recommended at the highest point, as a rule (Gurvich I.I., Boganik G.L. Seismic exploration. M., Nedra, 1980, p.126, 484-485) .

This method is widely used in practice, but it does not allow predicting oil and gas content, in addition, due to errors in seismic structures, a significant number of wells are opened by "empty" structures.

In some cases, to increase the efficiency of exploratory drilling, geochemical methods are additionally used (for example, the method according to ed. St. USSR No. 940117, M.cl. G 01 V 9/00, decl. 12.12.80, ed. St. USSR No. 949608, M.cl. G 01 V 9/00, claimed 25.12.80), biogeochemical testing (RF patent No. 2200334, M.cl G G V 9/00, declared 13.03.2002), identification of anomalies of the "fallow" type, methods of seismic stratigraphy, pattern recognition, etc. However, they do not always lead to the desired result. So, the efficiency of exploratory drilling (for oil) in the Volga-Ural province does not exceed 50% on average. When searching for hydrocarbons in the pre-Jurassic complexes of Western Siberia, with which many researchers currently have significant prospects, it is even lower, and even in the Paleozoic regions that are well studied, it amounts to 20-30%.

Based on the proposed concept that each oil field consists of a trap itself, a deep reservoir (as the main supplier of hydrocarbon fluids) and an oil supply channel connecting the deep reservoir to the trap, a method of oil production is known in which it is proposed to conduct oil production directly from the oil supply channel connecting the oil reservoir with a deep reservoir. To do this, it is necessary to establish the position of the oil supply channel, isolate it from the deposits and extract oil from it directly. In this method, the position of the oil supply channel is preliminarily determined, then the well is drilled to the horizons underlying the oil-bearing strata or to the surface of the crystalline basement. Around the circumference from the bottom of the main well below the bottom of the oil-saturated formation, horizontal wells are drilled through which the insulating substance is pumped, then the well is deepened, after which it is tested. The position of the oil supply channel is determined by preliminary field studies of wells that produce oil from the productive horizons of the sedimentary cover, as well as by preliminary geophysical studies of the sedimentary cover (RF patent No. 2204700, filed May 16, 2002, published May 20, 2003) . However, this method does not describe the specific technology for the search for oil supply channels.

The closest in technical essence is the method consisting in conducting deep seismic observations of the MOGT and identifying subvertical and steeply inclined dynamic anomalies (Deep seismic studies - a step towards understanding the process of formation of large hydrocarbon deposits // Trofimov.VA. - “State and prospects of using geophysical methods for solving urgent problems of prospecting, exploration and development of mineral deposits »materials of the Republican scientific and practical conference Nation, October, August 23-27, 1999. - October, 1999. - From 28-30).

In this method, only the initial stage of the search is proposed, which does not allow determining with sufficient reliability the degree of prospectivity of the identified anomalies.

To increase the efficiency of prospecting for oil and gas deposits, including those located at great depths and associated with complex traps, a method for searching for deposits and deposits of oil based on the identification and localization of deep reservoirs and oil supply channels is proposed. The method consists in establishing the oil and gas prospectivity of the territory by the presence of deep reservoirs in the earth's crust, for which they conduct seismic exploration of the MOGT in deep modification and identify volume dynamic anomalies, predict and localize the oil supply channels, and determine the degree of activity of the oil supply channel. For this purpose, the instability of the gravitational field is studied at the exit site of the oil supply channel by conducting gravimetric observations of different times at points fixed on the ground and determining at each of them changes in the gravitational field in time and by the presence of sections of increased instability of the gravitational field in time, they judge the current activity of the channel. The exploratory well is drilled directly to the active oil supply channel.

Prediction and localization of oil supply channels is carried out on the basis of seismic exploration in the 2D or 3D version. In areas where oil and gas is not proven, gravimetric observations are carried out in conjunction with geochemical surveys.

The essence of the method will be clear from the following description.

To detect deep reservoirs and predict on this basis the oil prospects of the territory, deep seismic exploration of the MOGT is carried out according to a technique that provides for the study of the earth's crust for its entire thickness. Data processing is carried out with the preservation of true amplitude ratios and should ensure the identification of volume anomalies representing the deep reservoir.

Oil supply channels are detected by 2D or 3D seismic exploration with a depth typically used in the study area or, preferably, slightly exceeding it. The best results can be achieved by 3D seismic. As a result of specialized processing, temporal sections reveal subvertical dynamic anomalies or inclined reflectors that display oil supply channels. The places of exits of the oil supply channels to the regional cover are the most promising for oil searches and subsequent production based on the previously proposed method (Korchagin V.I., Muslimov R.Kh., Nurgaliev D.K., Trofimov V.A. - Pat. RF No. 2204700 )

Gravimetric observations are carried out for several profiles passing through the exit point of the oil supply channel using the methodology for studying the instability of the gravitational field (GSP), which consists in repeated gravimetric measurements at points fixed on the ground, determining on each of them changes in the gravitational field in time. Based on the measurement results, areas of increased instability of the gravitational field are identified and the current channel activity is judged by them. If the channel is active and hydrocarbon fluids move along it, then the gravitational field in this place is characterized by increased instability in time. In areas where oil and gas potential has not been proven, it is advisable to combine gravimetric observations with geochemical surveys.

Thus, the method of searching for deposits and deposits of oil and gas is as follows:

1. Establishment of the oil and gas prospects of the territory by the presence in the earth's crust of the deep reservoirs detected by the seismic exploration of the MOGT, in the deep modification by volume dynamic anomalies.

2. Prediction and localization of oil supply channels based on seismic exploration, in the 2D or 3D version.

3. The identification of the degree of activity of the channel on the basis of gravimetric observations according to the GPS technique.

4. Drilling a prospecting well directly to an active oil supply channel.

Claims (4)

1. The method of searching for oil and gas fields and deposits, which consists in establishing the oil and gas potential of the territory by the presence of deep reservoirs in the earth’s crust, for which they conduct seismic exploration of MOGT in deep modification and distinguish volume dynamic anomalies, characterized in that they predict and localize the oil supply channels, revealing the degree of activity of the oil supply channel, for which the instability of the gravitational field is studied in the territory of the output of the oil supply channel by rovedeniya gravimetric lapse observing on fixed points on the ground and defining at each of them changes the gravitational field with time, and the presence of the raised portions instability gravitational field trial the channel current activity in time, carry out drilling exploratory well neftepodvodyaschy directly on the active channel. 2. The method of searching for oil and gas fields and deposits according to claim 1, characterized in that the prediction and localization of oil supply channels is carried out on the basis of seismic exploration in the 2D variant. 3. The method of searching for oil and gas fields and deposits according to claim 1, characterized in that the prediction and localization of oil supply channels is carried out on the basis of 3D seismic exploration. 4. The method of searching for deposits and deposits of oil and gas according to claim 1, characterized in that gravimetric observations are carried out in conjunction with geochemical survey.