RU2587661C1 - Method for development of explored oil deposit - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention can be used in development of low-explored oil deposit. During development of low-explored oil deposit drilling is performed with coarse grid of wells. Also, product is extracted through production wells, pumping of working agent through injection wells is performed. In drilled well seismic survey is carried out by non-longitudinal vertical seismic profiling with determination of zone of amplitudes of energy of reflected waves less than 80 standard units. Defined zone is accepted as shale-out zone in terrigenous reservoirs-non-reservoir. Further, transition zone is determined, having values of amplitudes of energy of reflected waves less than 80 to 120 standard units and zone of highly efficient collector with values of amplitudes of energy of reflected waves of more than 120 standard units. Method includes selecting a line separating transition zone and zone of highly efficient collector, determining thickness of oil-saturated formations in zone of highly efficient collector. Method then includes sealing existing grid of producers by drilling wells with horizontal bores in area of highly efficient collector with location in water-oil zone with oil-saturated strata of more than 3.5 m and pure oil zone with oil-saturated strata of more than 1.5 m. Horizontal boreholes are arranged opposite to line dividing transition zone and zone of highly efficient collector, and in parallel to section of said line opposite to which there is a well with horizontal shaft.

EFFECT: increased oil output.

1 cl, 1 dwg, 1 ex

Description

The proposal relates to the oil and gas industry and can be used in the development of oil little explored deposits.

A known method for the search and exploration of multilayer oil deposits confined to folds, characterized by the displacement of the arches of the lower and upper exploration floors, including, based on seismic data, drilling a prospecting well laid in the local elevation arch prepared along the upper exploration floor to the base horizon and based on statistical analysis geological and geophysical materials according to the ratio of the contours and arches of the lower and upper floors of oil potential, the search for the lower floor of the exploration route posting an exploratory well that is drilled to the rise in the profile of the layers with exploration well at a distance of 0.7-1.5 km from it. The search for the lower floor of the exploration is carried out by selective deepening of production wells from the approved technological scheme for the development of deposits on the upper floor of the exploration (RF patent No. 2159944, publ. 2000.11.27).

The method does not provide optimization of the location of production and injection wells, which entails high financial costs and drilling empty and aquifers.

Closest to the proposed invention in technical essence is a method of developing an oil little explored reservoir, including drilling a reservoir with a rare grid of design wells, taking products through production wells and injecting a working agent through injection wells. In a drilled well, detailed seismic surveys are carried out using the vertical seismic profiling method in the direction of elevated hypsometric marks of the structure in three directions diverging by no more than 60 (and no more than 600 m in length, the forecast structural plan of the productive formation is clarified, areas for increasing the hypsometric marks are identified, with confirmation of the forecast structural plan according to the research results, the project well is drilled in the direction of seismic profiles in the zone of elevated hypsometric marks at a distance of 300-400 m from the drilled one, if the forecast structural plan is not confirmed, the project well is moved to the zone of elevated hypsometric marks according to the new structural plan and drilled in a new place, adjusted according to the results of vertical seismic profiling and the presence of a cost-effective oil-saturated thickness of at least two m, casing the well and mastered as mining in the vault and / or near-water parts of the structures that control the oil and / or injection reservoir in the lower parts of the structures in urn region and not less than 70 m from the oil-bearing contour is corrected based on the results of drilling wells placement design (patent RF №2447270, Cl. E21 B 43/16, publ. 04/10/2012 - prototype).

The disadvantage of this method is that it does not make it possible to determine the clay zones in terrigenous reservoirs for the optimal placement of the project well stock.

The technical task of the invention is the most efficient placement of the project fund of horizontal and / or subhorizontal shafts and lateral horizontal shafts with different endings, taking into account the development of clay zones in terrigenous reservoirs and an increase in oil production.

The problem is solved in that in a method for developing an oil little explored reservoir, including drilling a reservoir with a rare grid of wells, taking products through production wells, injecting a working agent through injection wells, conducting a seismic survey using vertical seismic profiling in a drilled well, updating the forecast structural plan of a productive formation, drilling additional well, casing the well and development as production or injection, according to the invention seismic Buildings are carried out by the method of non-longitudinal vertical seismic profiling, the zone of values of the amplitudes of energy of reflected waves is determined less than 80 cu, a certain zone is taken as a claying zone in terrigenous reservoirs - a non-collector, a transition zone with values of amplitudes of energy of reflected waves of less than 80 to 120 cu is determined . and a zone of a highly productive reservoir with values of amplitudes of energy of reflected waves more than 120 cu, a line separating the transition zone and the zone of a highly productive collector is distinguished, the thickness of oil-saturated formations in the zone of a highly productive reservoir is determined, the existing grid of production wells is densified by drilling wells with horizontal shafts in the zone highly productive reservoir located in the water-oil zone with oil-saturated thicknesses of more than 3.5 m and a purely oil zone with oil-saturated strata s layers than 1.5 m, the horizontal stems are placed opposite the line separating a transition zone and a zone of highly collector, and in parallel to the said line, in front of which is placed a horizontal borehole barrel.

SUMMARY OF THE INVENTION

At the design stage, when compiling the main project document, when the question of determining the rational distribution of production and injection wells for each production facility based on the structural plan of the reservoir is being solved, there is a shortage of initial information, since this information was obtained from a rare grid of exploratory wells, and in the deposits small size is possible in a single drilled well. Therefore, an erroneous idea of the forecast structural plan, its hypsometric marks, and reservoir properties leads to insufficiently accurate determination of the location of the uplift that controls the reservoir and the thickness of the reservoir. The location and drilling of production and injection wells on the basis of the data obtained reduces the efficiency of drilling deposits, choosing a development system and increases financial costs. The proposed method solves the problem of the most efficient placement of the project fund of horizontal and / or subhorizontal shafts and lateral horizontal shafts with different endings, taking into account the development of clay zones in terrigenous reservoirs and increased oil production.

 The method is implemented as follows.

Drill a deposit with a rare grid of design wells. The structural plan of the productive formation is constructed according to the results of deep drilling and seismic studies (2D) on the developed deposit, seismic surveys are carried out using the method of non-longitudinal vertical seismic profiling in a drilled fund. Determine the zone of values of the amplitudes of the energies of the reflected waves of less than 80 cu A certain zone is taken as a claying zone in terrigenous reservoirs - a non-collector. The transition zone between the non-collector and the highly productive collector with the values of the amplitudes of the energies of the reflected waves of less than 80 to 120 cu is determined. and a zone of a highly productive collector with energy amplitudes of reflected waves of more than 120 cu A line is distinguished that separates the transition zone and the zone of the highly productive collector. Determine the thickness of oil-saturated formations in the zone of a highly productive reservoir. Condensation of the existing grid of producing wells is carried out by drilling wells with horizontal shafts in the zone of a highly productive reservoir with an arrangement in the oil-water zone with oil-saturated thicknesses of more than 3.5 m and a purely oil zone with oil-saturated thicknesses of more than 1.5 m. Horizontal shafts are placed opposite the line dividing the transition zone and the zone of the highly productive reservoir, and parallel to the section of the specified line, opposite which is placed a well with a horizontal wellbore.

As a result of the development, the oil recovery of the deposit increases, and the unproductive costs of drilling inefficient wells are reduced.

Concrete example

An oil reservoir is being developed (see Fig. 1) in the deposits of terrigenous carboniferous of the Bobrikov horizon. The linear dimensions of the reservoir are 1.8 × 2.9 km.

In FIG. 1 the following designations are adopted: 1 and 2 - external and internal oil contours, 3 and 4 - vertical production wells, 5 - injection well, 6 - zone of values of energy amplitudes of reflected waves less than 80 cu, 7 - line limiting zone 6 , 8 - transition zone with energy amplitudes of reflected waves less than 80 to 120 cu, 9 - highly productive zone with energy amplitudes of reflected waves more than 120 cu, 10 and 11 - part of the line dividing transition zone 8 and the zone of the highly productive collector 9, 12 is the inflection point between cha 10 and 11, 13 - oil-water zone, 14 - purely oil zone, 15, 16, 17 and 18 - horizontal shafts of producing wells.

The deposit is contoured by the external 1 and internal 2 oil circuit. Initially, the deposit is drilled with a rare grid of wells, i.e. two vertical producing 3 and 4 and one injection 5, which revealed less than 2 m of the reservoir in the oil-water zone, the position of which is determined on the basis of the hypsometric marks of the oil-water contact. Carry out their arrangement. Spend the selection of products through the production, the injection of the working agent through the injection well. According to core data and logging data in 3 wells, the properties of the reservoir are determined: depth 1200 m, reservoir temperature 25 ° C, reservoir pressure 12 MPa, porosity 28%, permeability 1.2 μm ² , oil saturation 92%. The reservoir is terrigenous. The oil has a density of 0.890 g / cm ³ and a viscosity of 25 MPa * s.

A structural plan of the reservoir is built using also 2D seismic data. From the constructions it follows that in a significant part of the reservoir the properties are not defined, therefore, further drilling of the reservoir is impossible.

In the first producing well 3, seismic surveys are performed using the non-longitudinal vertical seismic profiling method. Determine the zone - 6 values of the amplitudes of the energies of the reflected waves of less than 80 cu, limited by line 7. A certain zone is taken as the claying zone in terrigenous reservoirs - a non-collector. Determine the transition zone 8 with values of the amplitudes of the energies of the reflected waves less than from 80 to 120 cu and a zone of a highly productive collector 9 with energy amplitudes of reflected waves of more than 120 cu A line is distinguished that separates the transition zone 8 and the zone of the highly productive collector 9, consisting of two parts 10 and 11 and an inflection point 12 between them. According to 2D seismic data, the thickness of oil-saturated formations in the zone of highly productive reservoir 9 is determined. The existing grid of production wells is densified by drilling wells with horizontal shafts in the zone of highly productive reservoir 9 with location in the oil-water zone 13 with oil-saturated layer thicknesses over 3.5 m and pure oil zone 14 with oil-saturated layer thicknesses of more than 1.5 m. In this case, horizontal trunks 15, 16 and 17 are placed opposite and parallel to part 11 of the line dividing the transition zone 8 and the zone ysokoproduktivnogo collector 9. The horizontal hole 18 is placed opposite and parallel to the portion 10 of the line separating the transition zone 8 and the collector zone 9 highly productive.

Horizontal wells are drilled with a horizontal wellbore length of 150 m. After the development of horizontal wells, oil production rate of 75 tons / day with a water cut of 3% was obtained. They increased the volume of drained reserves by 10-15 times and the oil recovery factor by 5.3%.

Over 10 years, 191.4 thousand tons of oil and 287.2 thousand m ^{3 of} liquid were produced. As a result of drilling horizontal wells, the proposed method additionally produced 143.3 thousand tons of oil. With the cost of oil production 6138 rubles per ton and the price of oil 12800 rubles per ton, the savings over 10 years amounted to:

E = ΔQn · (C-C) = 6662 rubles. × 143300 = 954.7 million rubles.,

where ΔQн - additional oil production, thousand tons,

C is the price of oil, rubles / t,

C - the cost of production of one ton of oil, rubles / t,

those. according to the proposed method, the annual economic effect amounted to 95.5 million rubles.

The application of the proposed method will allow to extract additional oil.

Claims (1)

A method of developing a poorly explored oil reservoir, including drilling a reservoir with a rare grid of wells, taking products through production wells, injecting a working agent through injection wells, conducting a seismic survey using vertical seismic profiling in a drilled well, updating the forecast structural plan of a producing formation, drilling an additional well, casing a well and development as production, characterized in that the seismic survey is carried out by the method of non-longitudinal vert cial seismic profiling determine the zone values of the amplitudes of the reflected waves energies less than 80 cu defined zone for receiving claying zone in clastic reservoirs - non-reservoir define a transition zone with values of energies less than the amplitudes of reflected waves from 80 to 120 USD and a zone of a highly productive reservoir with values of amplitudes of energy of reflected waves more than 120 cu, a line separating the transition zone and the zone of a highly productive collector is distinguished, the thickness of oil-saturated formations in the zone of a highly productive reservoir is determined, the existing grid of production wells is densified by drilling wells with horizontal shafts in the zone highly productive reservoir located in the water-oil zone with oil-saturated thicknesses of more than 3.5 m and a purely oil zone with oil-saturated strata s layers than 1.5 m, the horizontal stems are placed opposite the line separating a transition zone and a zone of highly collector, and in parallel to the said line, in front of which is placed a horizontal borehole barrel.

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