CN105507858A

CN105507858A - Immiscible gas injection and oil replacement type exploitation method for ultra-deep fractured-vuggy carbonate reservoirs

Info

Publication number: CN105507858A
Application number: CN201510426154.1A
Authority: CN
Inventors: 江同文; 邓兴梁; 朱永峰; 范崇海; 李世银; 刘志良; 袁晓满; 李颖; 范文平
Original assignee: Dongying Shengruan Oil And Gas Exploration And Development Research Institute; Tarim Oilfield Branch Exploration And Development Institute
Current assignee: Shandong wins soft Polytron Technologies Inc; TARIM OILFIELD BRANCH, EXPLORATION AND DEVELOPMENT INSTITUTE
Priority date: 2015-07-20
Filing date: 2015-07-20
Publication date: 2016-04-20

Abstract

An immiscible gas injection and oil replacement type exploitation method for ultra-deep fractured-vuggy carbonate reservoirs includes steps: 1) injection test; 2) gas injection; 3) soaking; 4) oil exploitation. The gas in the step 2) is nitrogen normally used on site, and according to slim tube test results and theoretical calculation, nitrogen and crude oil vapor can be mixed and injected into shafts. Injection performed at the step 2) is carried out by a water-gas mixed injection manner, and gas injection for oil replacement can be carried out for several times. Replacement at the step 3) refers to judgment of whether oil-gas replacement is finished completely or not according to wellhead pressure monitoring data. The method has the advantages of safety in operation, oil recovery ratio increase, effectiveness, high efficiency and excellent effects according to application in a test area and is applicable to increase of recovery ratio after oil injection exploitation of the ultra-deep fractured-vuggy carbonate reservoirs.

Description

The gas injection of a kind of ultra-deep fracture and vug carbonate reservoir non-mixed phase is for oily exploitation method

Technical field

The present invention relates to carbonate rock oil-gas field development aspect technology, particularly a kind of non-mixed phase gas injection is for oily exploitation method.

Background technology

Ultra-deep fracture and vug carbonate reservoir reservoir space is Cave, crack and corrosion hole, reservoir is strong, Reservoir Body connectivity structure and mode of communicating complexity various, rely on natural energy primary recovery efficiency low, by supplementing oil reservoir energy after waterflooding extraction, can effective suggestions for improvement (patent of invention-fracture-cave type carbonate reservoir waterflooding oil replacement recovery method-publication number CN101942984A), but updip reservoir high-order bit remaining oil water-flooding performance is low around pit shaft, how to meet further raising pilot production well oil production under economic benefit prerequisite, it is the critical bottleneck problem improving recovery ratio after fracture-pore reservoir waterflooding extraction, still lack effective exploitation method at present.

Summary of the invention

The object of the present invention is to provide the gas injection of a kind of ultra-deep fracture and vug carbonate reservoir non-mixed phase for oily exploitation method, by injecting immiscible phase gas (as nitrogen) to oil reservoir, gravitational differentiation is utilized to be displaced by the attic oil that water drive cannot be employed, further raising oil recovery, obtains good economic benefits.

Technical scheme of the present invention is: the gas injection of a kind of ultra-deep fracture and vug carbonate reservoir non-mixed phase, for oily exploitation method, the steps include:

1) injection test, after ultra-deep fracture and vug carbonate reservoir waterflooding extraction is without economic benefit, before normal gas injection, carry out mining site injection test and be preferably applicable to the well location of gas injection for oil, then comprehensive analysis has geology and oil reservoir understanding, specifies individual well attic oil residual recoverable reserves scale, fracture and cave reservoir and pit shaft connected relation, in conjunction with Reservoir Body type, attic oil reserves and oil reservoir liquid-producing capacity, determine gas injection speed and injected gas volume;

2) gas injection, injects little and immiscible with the crude oil gas of appropriate density ratio crude oil in this oil reservoir;

3) stewing well, complete closing well after mining site gas injection operation, utilize injecting gas and oil density difference, allow gas and crude oil fully replace low-density gas by gravitational differentiation and to converge to reservoir high-order bit and form secondary pneumatic jack, thus the displacement of reservoir oil downwards, compacting gas-oil interface;

4) recover the oil, encryption admission well head oil pressure and casing pressure data, when the continuous 3-5 of a well head pressure days excursion is less than 0.5MPa, show that injecting gas and reservoir updip high-order bit attic oil have completed abundant displacement, opening well and making production crude oil, lead higher if gas returns row, need timely closing well again to divide different oil gas.

Injection test described in step 1) be effectively reduce injection device and well head bear pressure, determine the optimum gettering ability of oil reservoir simultaneously, WGR scope 1:100-1:1000 side/side need be designed, adopt the mode of aqueous vapor mixed water injection to carry out injection test, determine best day injection allocation amount and WGR.

The first run time injection rate of the injected gas volume described in step 1) is generally the 1/5-1/4 of attic oil reserves.

Step 2) described in gas be nitrogen, also can adopt nitrogen and crude oil gaseous mixture.

Step 2) in adopt the mode of aqueous vapor mixed water injection to inject.

Multiple round gas injection can be carried out for oily operation.

Whether the displacement described in step 3) judges that oil gas is fully replaced by well head pressure monitored data to complete.

The present invention, compared with existing technology, has handling safety, can improve oil recovery, and effective, efficiency is high, uses, have good effect, be applicable to the technology of the raising recovery ratio after ultra-deep fracture and vug carbonate reservoir waterflooding extraction through trial zone.

Accompanying drawing explanation

Fig. 1 is that the non-mixed phase gas injection of ultra-deep fracture and vug carbonate reservoir is for oil exploitation schematic diagram.

Fig. 2 is ultra-deep fracture and vug carbonate reservoir non-mixed phase gas-injection oil-production method implementing procedure figure.

Fig. 3 is fracture-pore reservoir Eor By Gas Injection laboratory physical simulation experiment tables of data.

Fig. 4 is final oil reservoir produced situation.

Detailed description of the invention

The gas injection of a kind of ultra-deep fracture and vug carbonate reservoir non-mixed phase, for oily exploitation method, the steps include:

1) injection test, after ultra-deep fracture and vug carbonate reservoir waterflooding extraction is without economic benefit, before normal gas injection, in some cycles, carry out mining site injection test, be preferably applicable to the well location of gas injection for oil, then comprehensively analyze existing geology and oil reservoir understanding, specify individual well attic oil residual recoverable reserves scale, fracture and cave reservoir and pit shaft connected relation, in conjunction with Reservoir Body type, attic oil reserves and oil reservoir liquid-producing capacity, determine gas injection speed and injected gas volume.

2) gas injection, injects little and immiscible with the crude oil gas of appropriate density ratio crude oil in this oil reservoir; In debt with supplementary oil reservoir, renwing stratum energy, suppresses rate of water cut increase, as reservoir pressure is higher, the mode of aqueous vapor mixed water injection can be adopted to inject, to reduce the pressure requirements of well head and injection device.

3) stewing well, complete closing well after mining site gas injection operation, utilize injecting gas and oil density difference, allow gas and crude oil fully replace low-density gas by gravitational differentiation and to converge to reservoir high-order bit and form secondary pneumatic jack, thus the displacement of reservoir oil downwards, compacting gas-oil interface (as shown in Figure 1).

4) recover the oil, encryption admission well head oil pressure and casing pressure data, when the continuous 3-5 of a well head pressure days excursion is less than 0.5MPa, show that injecting gas and reservoir updip high-order bit attic oil have completed abundant displacement, opening well and making production crude oil, lead higher as initial stage gas returns row, need timely closing well again to divide different oil gas.

Step 2) in gas be that scene generally adopts nitrogen, according to slim-tube test achievement and theory calculate, nitrogen and crude oil gas-vapor mix injection mode also can be adopted to inject pit shaft.

Step 2) in adopt the mode of aqueous vapor mixed water injection to inject.

Multiple round gas injection can be carried out for oily operation (experimental data is as Fig. 3).

Whether the displacement described in step 3) judges that oil gas is fully replaced by well head pressure monitored data to complete.(the final extraction situation of oil reservoir is as Fig. 4).

Claims

1. the gas injection of ultra-deep fracture and vug carbonate reservoir non-mixed phase is for an oily exploitation method, it is characterized in that: step is:

2. a kind of ultra-deep fracture and vug carbonate reservoir non-mixed phase gas injection according to claim is for oily exploitation method, it is characterized in that: the injection test described in step 1) be effectively reduce injection device and well head bear pressure, determine the optimum gettering ability of oil reservoir simultaneously, WGR scope 1:100-1:1000 side/side need be designed, adopt the mode of aqueous vapor mixed water injection to carry out injection test, determine best day injection allocation amount and WGR.

3. a kind of ultra-deep fracture and vug carbonate reservoir non-mixed phase gas injection according to claim, for oily exploitation method, is characterized in that: the first run time injection rate of the injected gas volume described in step 1) is generally the 1/5-1/4 of attic oil reserves.

4. a kind of ultra-deep fracture and vug carbonate reservoir non-mixed phase gas injection according to claim for oily exploitation method, is characterized in that: step 2) in gas be nitrogen, also can adopt nitrogen and crude oil gaseous mixture.

5. a kind of ultra-deep fracture and vug carbonate reservoir non-mixed phase gas injection according to claim for oily exploitation method, is characterized in that: step 2) in adopt the mode of aqueous vapor mixed water injection to inject.

6. a kind of ultra-deep fracture and vug carbonate reservoir non-mixed phase gas injection according to claim, for oily exploitation method, is characterized in that: as carried out multiple round gas injection for oily operation.

7. a kind of ultra-deep fracture and vug carbonate reservoir non-mixed phase gas injection according to claim, for oily exploitation method, is characterized in that: whether the displacement described in step 3) judges that oil gas is fully replaced by well head pressure monitored data to complete.