CN102477849A - Selective water-plugging technological process - Google Patents

Abstract

The invention discloses a selective water-plugging technological process which comprises the following technological steps: (1) general squeezing of a complete well: the difference between the development degrees of longitudinal cracks of carbonate reservoirs creates conditions for the general squeezing of a complete well; and (2) packer removal: if the difference between the longitudinal permeabilities of the reservoirs is small, oil and water are evidently stratified, and for enabling a water-shutoff agent to effectively enter into a main water exit interval, a packer is necessarily removed. By using the technological process disclosed by the invention, the effects of stabilizing the oil output and controlling the water content can be achieved.

Description

A kind of selective water-plugging technology method

Affiliated technical field

The present invention relates to a kind of selective water-plugging technology method, belong to field of petroleum exploitation.

Background technology

The water outlet of oil gas well is a ubiquitous problem in the oilfield development process; Particularly adopt the waterflooding extraction mode, along with the propelling of waterside edge, because the stratum non-homogeneity is serious; Reasons such as the difference of profit mobility ratio and development plan and improper measures; All can cause the oil field rate of water cut increase to be accelerated, cause the too early water logging of oil reservoir, oil recovery rate reduces.At present, high water-cut stage during many in the world oil fields all get in succession, and underground recoverable reserves is still bigger, high water-cut stage during China's main oilfield has also got into, 62% of existing only extraction water flooding recovery reserves.The increasing yield and injection measure efficient of extensive use under the original annotation water condition is more and more lower, and technical difficulty is increasing, production decline, and aquifer yield increases considerably, deficiency in economic performance.So, be badly in need of seeking effective new method, improve high moisture produce oil effect.Current utilization measure more widely is exactly a profile control and water plugging technology, and it is under the constant situation of former offtake pattern, to realize through adjustment payzone structure.Water injection well profile control and producing well water-plugging technique have carried out using widely at the scene, have improved injection ripples and volume effectively, have adjusted the oil reservoir mining structure, improved output, thereby it are a kind of key technologies in the waterflooding extraction process.Water-blocking operation is " a control water-oil factor " or " water is produced in control ".Its essence is to change the flow behavior of water in the stratum, promptly change the percolation law of water on the stratum.Water-blocking operation can carry out on oil well (producing well), also can on water injection well, carry out, and the former is called oilwell water shutoff usually, and the latter is called the water injection well profile control.In oil well production, a large amount of extraction of formation water have brought many unfavorable factors to oil well production, ground processing facility, and therefore steady oil control water is important content in the field produces.

Summary of the invention

(1) processing step:

The full well of a generally squeezes stifled

The difference of Carbonate Reservoir reservoir longitudinal crack development degree is for full well generally squeezes the stifled condition of having created.And the oil well water breakthrough mainly is that epicone causes because end water is along height infiltration seam hole; Main production fluid section is in the pit shaft bottom; Behind the oil well water breakthrough, main production fluid section is exactly main water exit end usually, and the permeability of water exit end and water saturation are higher than fuel-displaced section; This just is that the possibility that stifled agent can preferentially get into water outlet seam hole provides geological conditions in general crowded the blocking up of full well.

The b lower packet

If reservoir longitudinal permeability difference is little, profit has obvious layering, gets into main water exit interval effectively for making stifled agent, just must lower packet.This mode is suitable for oil reservoir and bores that to open thickness big, the many and little oilwell water shutoff of permeability difference of crack section.Owing to be that big interval is separated, squeeze when blocking up and must under the little discharge capacity of low pressure, carry out, make stifled agent shutoff water outlet seam hole effectively.

(2) squeeze blocking method:

The fractured carbonate rock oil reservoir adopts the stifled agent water blockoff of polyacrylamide; Usually take the taper slug to squeeze stifled mode; It is higher than the crowded stifled success rate of continuous slug; This method is to make leading edge with colloidal sol, and the gel slug can improve near the shut-off capacity the pit shaft, to early stage water blockoff or produce section less and the little well of thickness preferably.This is because colloidal sol has selectivity preferably, can play the effect of adjusting the profit mobility ratio again at earth formation deep, with the fingering of restriction water.When oil well production, near pit shaft, there is bigger pressure to fall, stifled agent is prone to broken through, must be with the shutoff of high-strength gel body, can control the channelling of water and colloidal sol is counter arranges, obtain water plugging effect preferably.But grow for the seam hole, the oil well that multi-section multi-layer is produced will note improving the plugging strength of whole slug, should adopt variable concentrations or different types of gel taper shutoff.Taper is stopped up and is squeezed stifled mode because viscous fingering is less, and polyacrylamide solution can evenly penetrate, thereby has guaranteed sweep efficiency and shutoff efficient to water outlet seam hole.

Squeeze pressure

The selection principle of squeeze pressure is to surpass 80% of formation fracture pressure on the one hand; To keep suitable squeeze pressure on the other hand, too lowly satisfy not the discharge capacity requirement, too highly can pollute permeable formation.

Under certain driving pressure, permeability is high more, and flow resistance coefficient is more little, and fluid passes through more easily.Equally, in squeezing stifled process, stifled agent gets into the starting pressure difference of duct, the crack requirement of different permeabilities.Think that thus as long as stifled pressure is squeezed in control, stifled agent can get into high infiltration (water outlet) seam hole effectively under the pressure reduction in relatively little clamp-oning.

In the formula: P _Open---starting pressure MPa,

α---constant

σ _O-w---the oil water interfacial tension newton/meter

K---reservoir permeability 10 ^-3μ m ²

Visible by following formula:

Under the normal condition, after stifled agent gets into the stratum, the stifled agent of viscosity diffusion around well, pressure " climbing " gradually rises, and sets up " climbing pressure ".Climbing pressure has reflected the variation of stifled agent percolation ability and direction in the stratum, also is the important indicator of evaluating the construction technology resonable degree." climbing " do not occur if pressure, explain that the absorptive capacity on stratum is very strong, big seam hole or leakage interval are arranged, prove that stifled agent and formation condition are incompatible, at this moment should manage to set up " climbing pressure ".Otherwise initial pressure is high, and " climbing pressure " is also high, and the poor permeability on stratum is described, does not adjust the speed of clamp-oning or reduces dosage, certainly will make stifled agent invade fuel-displaced seam hole and damage, and at this moment should control " climbing pressure ".

Squeeze note speed:

Speed is clamp-oned in control, and the one, guarantee that the shear degradation of polyacrylamide is reduced to minimum level; The 2nd, stifled agent can preferentially get into high infiltration water outlet and stitch the hole in crowded blocking up.

High molecular polymer is in flow at high speed, because of degradation takes place mechanical shearing.The polyacrylamide shear degradation is to begin during greater than 1000s-1 to occur in shear rate, becomes serious when reaching 5000s-1.Mechanical shearing will make the chain rupture of polyacrylamide amine molecule, and viscosity descends, and therefore control is clamp-oned speed and at first made shear degradation arrive the needs of minimum speed.The crack of different development degrees, it is different that it starts pressure reduction, and the startup pressure reduction that high infiltration seam hole requires is less.Therefore, speed is clamp-oned in control, and the under low pressure inevitable high infiltration water outlet seam hole that at first gets into of stifled agent suppresses the channelling of water effectively.

Plug agent amount:

The selection of stifled agent comprises the selection of stifled agent type and the calculating of plug agent amount.

Used stifled agent at present mainly is divided into two big types, and one type is the stifled agent of granular pattern, and another kind of is the stifled agent (comprising frozen glue, gel etc.) of non-granular pattern.The selection of stifled agent type should confirm that the stifled agent particle diameter of general requirements is that 1/9～1/3 of formation pore diameter is advisable according to the size in aperture, stratum.

The pore size of high permeability zone can be by computes:

$r=\frac{2}{7\×{10}^3}\·\sqrt{\frac{K}{\mathrm{\φ}}}$

In the formula: r---pore size, cm;

K---permeability, μ m ²

φ---degree of porosity

The r value that estimates in this way can be used to instruct the selection of stifled agent.

Say that in a sense what plug agent amount was represented stifled agent gos deep into radius or range of scatter, influence the water blockoff period of validity, so must be rationally definite.Suppose that reservoir is homogeneous (actual is heterogeneous body), water saturation 100%, horizontal radial stream (in fact stifled agent is at first extended diffusion along major fracture) is made in stifled agent, can calculate by the volumetric method formula:

Q＝πR ²hΦS _W

In the formula: h-processing section thickness, m;

Φ-fracture porosity, %;

S _w-water saturation, %;

The stifled agent of R-is goed deep into radius, m;

The Q-plug agent amount, m ²

The specific embodiment

(1) full well generally squeezes stifled: the difference of Carbonate Reservoir reservoir longitudinal crack development degree, and for full well generally squeezes the stifled condition of having created.

(2) lower packet: if reservoir longitudinal permeability difference is little, profit has obvious layering, gets into main water exit interval effectively for making stifled agent, just must lower packet.

Claims (1)

1. selective water-plugging technology method is characterized in that comprising following processing step:

(1) full well generally squeezes stifled: the difference of Carbonate Reservoir reservoir longitudinal crack development degree, and for full well generally squeezes the stifled condition of having created.

(2) lower packet: if reservoir longitudinal permeability difference is little, profit has obvious layering, gets into main water exit interval effectively for making stifled agent, just must lower packet.