CN101016828A

CN101016828A - Foam negative pressure mixed discharging plug removal method

Info

Publication number: CN101016828A
Application number: CN 200710013467
Authority: CN
Inventors: 李兆敏; 李宾飞; 张继国; 才巨宏; 赵洪涛
Original assignee: China University of Petroleum East China
Current assignee: China University of Petroleum East China
Priority date: 2007-02-02
Filing date: 2007-02-02
Publication date: 2007-08-15
Anticipated expiration: 2027-02-02
Also published as: CN100537999C

Abstract

The invention provides a foam passive pressure mixing storage layer release technique, comprising that using foam throughout, passive pressure mixing discharging, and using the solid carrier ability of foam and large well pressure difference to discharge the solid particles and organic deposit from ground layer to release block, and uses the high-speed flow with solid particles to wash the pressed band from inner to outer on the canon eye. The invention can be used to release the block in drilled well, canon eye or the like.

Description

Foam negative pressure mixed discharging plug removal method

Technical field:

The present invention relates to the reservoir blockages relieving technology in a kind of oil development process.

Background technology:

In the oil development process, because the influence of factors such as working fluid (as mud) leakage, near wellbore zone solid particle migration, clay swell, organic matter precipitation, inevitably can cause reservoir damage, cause reservoir obstruction, near wellbore permeability reduction, oil well output to descend.In order to recover oil well output, generally to carry out the de-plugging operation, block releasing technique commonly used mainly contains acidification to dispel block, organic solvent de-plugging and hydraulic oscillation de-plugging etc.Acidification to dispel block is mainly used in removes inorganic obstruction (as solid particle, fouling etc.), but is not suitable for acid-sensitive stratum; The organic solvent de-plugging is applicable to that mainly organogenous sediment stops up (as near the colloid the pit shaft, asphaltene precipitation); The hydraulic oscillation de-plugging mainly is to produce wave of oscillation flushing perforation borehole by high-pressure water jet to carry out de-plugging.Preceding two kinds method for removing blockage institute dosage is big, cost is higher, and applicable elements is single relatively; A kind of block releasing technique sphere of action in back is limited, can only remove the borehole top layer and stop up.

Technology contents:

The objective of the invention is to remove the near wellbore zone and stop up,, improve oil well output to recover in-place permeability.

The object of the present invention is achieved like this: by foam handle up, negative pressure mixed discharging, rely on the big bottom hole pressure difference that carries solia particle ability and formation by force of foam, obstructions such as the solid particle of near wellbore zone and organogenous sediment are discharged the stratum, simultaneously, utilization carries the high speed of solia particle and returns the current drainage body, compaction band to borehole washes from inside to outside, and mediation perforation borehole reaches and removes the purpose that reservoir stops up.Specifically realize as follows:

(a). inject a certain amount of nitrogen foam in the stratum, foam density is 0.6g/cm ³～0.8g/cm ³, injection rate is 0.3L/min～0.5L/min, the highest injection pressure can not surpass 20MPa.Injection rate is by formula Q= π r ²H determines that in the formula, Q is for injecting foam volume, (m ³);  is a formation porosity, decimal; R is a plug removal radius, (m); H is a core intersection, (m).Plug removal radius is generally got 0.3 m～0.5m, and therefore, injection rate depends primarily on core intersection and degree of porosity.

(b). with 1～3 circulation of low-density nitrogen foam circulation well cleanup, the density of foam is 0.2g/cm ³～0.5g/cm ³, injection rate is 0.4L/min～0.6L/min, reduces bottom pressure, in the control bottom hole pressure difference 10Mpa, relies on the foam and the gas expansion of the row of returning at a high speed, and the solid particle and the organogenous sediment of near wellbore zone carried out the stratum.Simultaneously, utilize the high speed carry solia particle to return the current drainage body, the compaction band of perforation borehole is washed from inside to outside, mediation perforation borehole reaches the effect of jet de-plugging.

Aerated fluid is a kind of compressible gas-liquid mixture, have characteristics such as density is low, easy to adjust, apparent viscosity is high, the row's of helping performance is good, have the very strong solia particle ability of carrying when in the stratum, flowing, can control bottom hole pressure difference very easily, reach the row's of helping effect preferably.

The specific embodiment:

Describe the present invention in detail below in conjunction with embodiment.

Embodiment 1: behind drilling completion, because the reservoir pollution that causes of lose returns and, can adopt the foam negative pressure mixed discharging plug removal technology to remove reservoir pollution, dredge the perforation borehole from inside to outside because the borehole compaction band that perforation causes has considerable influence to oil well productivity.Oil well with well depth 1000m is an example, and concrete scheme is: at first inject a certain amount of nitrogen foam in the stratum, foam density is 0.7g/cm ³, injection rate is according to formula Q= π r ²H determines that get plug removal radius r=0.4m, injection rate is 0.3L/min～0.5L/min, and the highest injection pressure can not surpass 15MPa; Be 0.2g/cm with density then ³2 circulations of nitrogen foam circulation well cleanup, injection rate is 0.4L/min～0.5L/min, reduces bottom pressure, increases the pressure reduction between stratum and shaft bottom, but the control bottom hole pressure difference is not more than 10MPa, lure that the foam that has injected returns discharge at a high speed into, when foam returns row leakage is advanced the mud and the parts of fine flour sand on stratum and take out of together, meanwhile, the high speed that carries solid particle is returned the current drainage body, compaction band to borehole washes from inside to outside, has dredged the perforation borehole, thereby removes formation blockage.

Embodiment 2: the relatively poor oil reservoir of sorting, loose sand heavy crude reservoir particularly, after producing a period of time, the near wellbore zone is stopped up serious, obstruction mainly is solid particle and colloid, bitum organogenous sediment, can adopt foam negative pressure mixed discharging plug removal method provided by the present invention to remove formation blockage.Oil well with well depth 1000m is an example, and concrete scheme is: at first inject a certain amount of nitrogen foam to the stratum, foam density is generally 0.7g/cm ³, injection rate is 0.3L/min～0.5L/min, and the highest injection can not surpass 12MPa, and injection rate is according to formula Q= π r ²H determines, gets plug removal radius r=0.3m; Be 0.3g/cm with density then ³1.5 circulations of low-density nitrogen foam circulation well cleanup, injection rate is 0.4L/min～0.5L/min, reduce bottom pressure, increase the pressure reduction between stratum and shaft bottom, but the control bottom hole pressure difference is not more than 8MPa, luring that the foam that has injected returns at a high speed into ejects, and will stop up the fine silt on stratum and discharge together with organogenous sediment when foam returns row, thereby remove formation blockage.

The present invention by foam handle up, negative pressure mixed discharging, utilize the big bottom hole pressure difference that carries solia particle ability and formation by force of foam, obstructions such as the solid particle of near wellbore zone and organogenous sediment are discharged the stratum, remove reservoir to stop up; Utilize the high speed that carries solid particle to return the current drainage body simultaneously, the compaction band to borehole washes from inside to outside, mediation perforation borehole, and this is that other de-plugging process institute is inaccessiable.

Claims

1. foam negative pressure mixed discharging plug removal technology, it is characterized in that by foam handle up, negative pressure mixed discharging, the solid particle and the organogenous sediment obstruction of near wellbore zone are discharged the stratum, remove reservoir and stop up, specifically implement as follows:

(a). inject a certain amount of nitrogen foam in the stratum, foam density is 0.6g/cm ³～0.8g/cm ³, injection rate is 0.3L/min～0.5L/min, injection rate is by formula Q= π r ²H determines that in the formula, Q is for injecting foam volume, and  is a formation porosity, and r is a plug removal radius, and h is a core intersection;

(b). with density is 0.2g/cm ³～0.5g/cm ³1～3 circulation of low-density nitrogen foam circulation well cleanup, injection rate is 0.4L/min～0.6L/min, reduce bottom pressure, in the control bottom hole pressure difference 10Mpa, rely on the foam and the gas expansion of the row of returning at a high speed, the solid particle and the organogenous sediment of near wellbore zone carried out the stratum; Simultaneously, utilize the high speed carry solia particle to return the current drainage body, the compaction band of perforation borehole is washed from inside to outside, mediation perforation borehole reaches the effect of jet de-plugging.

2. foam negative pressure mixed discharging plug removal method according to claim 1 is characterized in that the plug removal radius in the injection rate design formulas is got 0.3m～0.5m.