CN102518414A - Test method for fracture-cavity carbonate condensate gas reservoir water injection substituting gas experiment - Google Patents

Abstract

The invention relates to a test method for a fracture-cavity carbonate condensate gas reservoir water injection substituting gas experiment, which comprises the following steps in sequence: (1) manufacturing a fracture-cavity carbonate core model; (2) preparing a condensate gas sample and injecting water, and setting a pressure point p1 for performing water injection and a pressure point p2 for ending the water injection; (3) restoring a core into an original state; (4) conducting a depletion experiment (5) performing the water injection substituting gas experiment at the formation temperature; (6) when the pressure of the core reaches abandonment pressure, gradually reducing the pressure of the bottom end of the core to barometric pressure; discharging all oil-gas water in the core to obtain reserves of natural gas and condensate oil of the core; and (7) working out the recovery ratio of the condensate oil and the natural gas. According to the test method for the fracture-cavity carbonate condensate gas reservoir water injection substituting gas experiment, through manufacturing a single-fracture plane full-diameter fracture-cavity core physical model for keeping the core complete, the test method for a water injection substituting gas physical analog experiment is established, and a tool and a measure are provided for evaluating a recovery effect on fracture-cavity carbonate.

Description

Seam hole type carbonate gas condensate reservoir water filling is for gas experiment test method

Technical field

The present invention relates to the seam hole type gas condensate reservoir water filling of petroleum natural gas exploration field improves condensate, gas recovery ratio for gas experiment test method.

Background technology

Seam hole type carbonate rock gas condensate reservoir is different from general sandstone reservoir, when well is got to seam top, hole, because the existence of seam causes a large amount of leakages of drilling fluid, therefore can't get to the bottom of seam unit, hole; Has only a bite well and much stitch unit, hole well number, when carrying out depletion and produce, because condensate is distributed in the bottom in hole after separating out; Therefore can't extraction, the condensate loss is big, and the conventional waterflooding method can not improve the CONDENSATE OIL AND GAS recovery ratio effectively; Water filling can prevent that for gas condensate from separating out in a large number; On the other hand, after water is annotated into the seam hole, thereby, action of gravity will stitch oil gas pop-up in the hole because can being deposited on the bottom in hole and being full of the seam hole; Up to extraction, thereby improve condensate, gas recovery ratio effectively.

Summary of the invention

The object of the invention is to provide seam hole type carbonate gas condensate reservoir water filling for gas experiment test method; This method principle is reliable; Easy and simple to handle, can effectively simulate the gas condensate reservoir water filling for the gas process, for the exploitation effect of estimating seam hole type carbonate gas condensate reservoir provides instrument and means.

For reaching above technical purpose, the present invention provides following technical scheme.

Seam hole type carbonate gas condensate reservoir water filling may further comprise the steps for gas experiment test method successively:

(1) makes seam hole type carbonate rock core model

Select the square carbonate rock core of a length of side in the scope of the 30cm left and right sides, carry out manual work and make nature list seam, require the seam face to be roughly parallel to any rib of square and run through whole rock core; Drill through full-hole core with 4 inch diameter drill bits; Length can reach 10-25cm, requires seam to be positioned at full-hole core central authorities as far as possible, then the hole is made in full-hole core inside; Hole number and size by actual gas reservoir hole degree of porosity with size, determine after the Distribution calculation; But the edge and the end face of rock core can not be passed in the hole, form the built-up pattern that a single naturally seam face is cut all holes open, and rock core keeps the vertical fracture mode of communicating to place.

(2) preparation condensate gas sample and injection water

According to stratum condensate gas PVT report preparation condensate gas sample, it is close to require under formation temperature pressure, to guarantee that condensate content, dew point, constant volume depletion condensate saturation ratio and this stratum condensate gas PVT report, and sets a suitable pressure spot p who carries out water filling ₁The pressure spot p of (generally be higher than the condensate gas dew-point pressure and be lower than the gas reservoir strata pressure) and end water filling ₂(p ₂Compare p ₁High several MPa).

Provide stratum water sample analysis data preparation to inject water according to the scene simultaneously.

(3) rock core being carried out reset condition recovers

With pack into core holding unit and vertically placing of rock core; Rock core is cleaned, dries, finds time; Use the dry gas saturated core; The control rock core pressure at two ends of walking unhurriedly lets in the rock core pressure rising of walking unhurriedly, and pressure reaches strata pressure (outlet holds one's breath) and stablizes a period of time and note saturated dry gas volume V in the rock core _F1(being the voids volume of rock core) is so that examine usefulness as stratum gas reserves.Under formation temperature and strata pressure (being higher than the condensate gas dew-point pressure), replace dry gas in the rock core with the condensation gas drive for preparing from bottom to top; Consistent up to the rock core bottom with the top gas-oil ratio, this moment rock core in condensate gas saturation capacity

(4) carry out the depletion experiment

Close rock core bottom valve, begin to carry out depletion base area stressor layer and p from strata pressure from upper end ₁Difference divide what depletion; Every grade of step-down 2～3MPa; Every grade of depletion is carried out as follows: progressively reduce control rock core top pressure, can at the uniform velocity be given vent to anger by (oil) in the top, when pressure drops to the pressure spot of setting; Remain on this pressure spot till the top holds one's breath (oil), the liquid quality and the gas volume of extraction when this pressure spot is arrived in record depletion.

Pressure drops to p when the rock core top ₁, keeping top pressure is p ₁No longer give vent to anger up to the top, note from strata pressure depletion and exploit pressure p ₁The time extraction the condensate mass M _O0With natural gas volume V _G0

(5) under formation temperature, carry out water filling for the gas experiment

Keeping rock core pressure is p ₁, inject formation water from the rock core top to rock core, when pressure reaches p ₂The time stop water filling, note water injection rate V for the first time _W1, close rock core top valve, stablize more than 4-6 hour, open this valve again and carry out blowdown, when pressure drops to p ₁And when no longer give vent to anger in the top, write down the tolerance V that the rock core top goes out through gas-liquid separator separates _G1, and through the isolated oil mass M of oil water separator _O1With water yield M _W1, accomplish water filling for the first time for gas.

So circulation is till produce oil (gas) not.

Obtain a series of water injection rate V thus _W1, V _W2, V _W3..., V _Wi, gas production V _G1, V _G2, V _G3..., V _Gi, oil production M _O1, M _O2, M _O3..., M _Oi, aquifer yield M _W1, M _W2, M _W3..., M _Wi(i is that the gas number of times is replaced in water filling), thus obtain through the condensate gross mass M of i water filling for the gas extraction _OtiWith natural gas cumulative volume V _Gti:

M _oti＝M _o1+M _o2+M _o3+…+M _oi

V _gti＝V _g1+V _g2+V _g3+…+V _gi

When water filling for gas injection rate and produced quantity become than hour, can reduce p ₁And p ₂, also can increase p ₂-p ₁, can obtain condensation oil and gas recovery percent of reserves under the difference of different pressures level is handled up pressure reduction like this, for the optimization process system of handling up provides foundation.

(6), rock core pressure (according to circumstances confirms) when reaching the gas reservoir abandonment pressure by actual gas field; Close rock core top valve, open rock core bottom valve, pressure is reduced to atmospheric pressure gradually; Emit all oil gas water in the rock core, get natural gas gas production V to the end in the rock core bottom _gAnd the pressure oil, the water volume V that emit during for atmospheric pressure _o, V _w, simultaneously at V _gIn add in the rock core the not gas volume of extraction Thereby obtain rock core gas reserves V _Gt:

V _gt＝V _g0+V _g1+V _g2+V _g3+…+V _gi+V _g+V _f1-V _o-V _w

Based on condensate gas initial gas oil ratio, just can calculate condensate in place N in the rock core:

$N=\frac{V_{\mathrm{gt}}}{\mathrm{GOR}}{\mathrm{\ρ}}_o$

According to gas reserves V in the rock core _GtVolume factor B with condensate gas under condensate gas and natural gas ground volume ratio and the formation temperature strata pressure in the PVT report _g, calculably the layer condition under the condensate gas volume

V _F2=V _GtGround volume ratio * the B of * condensate gas and natural gas _g

Test

explains that then the volume coincidence rate is higher, and data are reliable.

(7) recovery ratio through the computes condensate is R _OiRecovery ratio R with natural gas _Gi:

$R_{\mathrm{oi}}=\underset{0}{\overset{i}{\mathrm{\Σ}}}{M}_{\mathrm{oi}}/N\×100\%$

$R_{\mathrm{gi}}=\underset{0}{\overset{i}{\mathrm{\Σ}}}{V}_{\mathrm{gi}}/V_{\mathrm{gt}}\×100\%.$

The water filling of i level is for gas gas-oil ratio GOR _iAnd gas-water ratio GWR _i:

GOR _i＝V _gi/M _oi×ρ _o

GWR _i＝V _gi/M _wi×ρ _w

In the formula:

GOR is a condensate gas initial gas oil ratio;

GOR _i, GWR _i: be respectively the water filling of i level for airsetting gassing gas-oil ratio and gas-water ratio, ml/ml;

ρ _o, ρ _w: be respectively the density of ground condensate and water, g/ml;

M _Oi, M _Wi, M _GiBe respectively the water filling of i level for the condensate of gas extraction, the quality (g) and the natural gas volume (ml) of formation water;

N: condensate in place in the rock core, g;

V _Gt: gas reserves is at mark attitude lower volume, ml in the rock core;

M _O0, V _G0: water filling is for the condensate quality (g) and the amount of natural gas (ml) of depleted extraction before the gas.

Compared with prior art, the present invention has following beneficial effect:

(1) set up a kind of full diameter seam of monolete face hole rock core physical model preparation method that keeps the rock core integrality;

(2) set up the experiment test method of water filling, for the exploitation effect of estimating seam hole type carbonate provides instrument and means for the gas physical analogy.

The specific embodiment

Further specify the present invention according to instance below.

Seam hole type carbonate gas condensate reservoir water filling may further comprise the steps for gas experiment test method successively:

(1) makes seam hole type carbonate rock core model; Select the square carbonate rock core of a size about 30cm; Carry out manual work and make nature list seam; With 4 inch diameter bit drills corings and make the hole, the edge and the end face of rock core can not be passed in the hole, forms a single naturally seam section and cuts the built-up pattern in all holes;

(2) preparation condensate gas sample and injection water are set the pressure spot p that carries out water filling ₁With the pressure spot p that finishes water filling ₂

(3) rock core is carried out reset condition and recover, use the dry gas saturated core, the condensate gas that usefulness prepares under formation temperature and strata pressure is dry gas in the displacement rock core from bottom to top;

(4) carry out the depletion experiment from the rock core top, note from strata pressure depletion and exploit pressure p ₁The time extraction the condensate mass M _O0With natural gas volume V _G0

(5) under formation temperature, carry out water filling for the gas experiment from the rock core top, rock core pressure is p ₁The time, inject formation water from the rock core top to rock core, when pressure reaches p ₂The time stop water filling, note water injection rate V for the first time _W1, close rock core top valve, stablize 4-6 hour after, open this valve again and carry out blowdown, write down the tolerance V that the rock core top goes out through gas-liquid separator separates _G1, and through the isolated oil mass M of oil water separator _O1With water yield M _W1, so circulation is till produce oil (gas) not;

(6) when rock core pressure reaches abandonment pressure, close rock core top valve, open the rock core outlet at bottom, pressure is reduced to atmospheric pressure gradually, emit all oil gas water in the rock core, get natural gas gas production V to the end in the rock core bottom _gAnd oily, water volume V _o, V _wThereby, obtain rock core gas reserves V _GtWith condensate in place N;

(7) recovery ratio of calculating condensate is R _OiRecovery ratio R with natural gas _Gi

Claims (1)

1. seam hole type carbonate gas condensate reservoir water filling may further comprise the steps for gas experiment test method successively:

(1) selects the square carbonate rock core of a length of side about 30cm; Carry out manual work and make nature list seam, the seam face is roughly parallel to any rib of square and runs through whole rock core, drills through full-hole core with 4 inch diameter drill bits; Length reaches 10-25cm; Seam is positioned at full-hole core central authorities as far as possible, and the hole is made in full-hole core inside, and the hole number determines by actual gas reservoir with size;

(2) according to stratum condensate gas PVT report preparation condensate gas sample, provide stratum water sample analysis data preparation to inject water, set the pressure spot p that carries out water filling according to the scene ₁With the pressure spot p that finishes water filling ₂

(3) rock core is carried out reset condition and recover,, use the dry gas saturated core, note saturated dry gas volume V pack into core holding unit and vertically placing of rock core _F1, under formation temperature and strata pressure, replace dry gas in the rock core with the condensation gas drive for preparing, consistent up to the rock core top with the bottom gas-oil ratio;

(4) close rock core bottom valve, begin to carry out the depletion experiment from the rock core top from strata pressure, pressure drops to p when the rock core top ₁, keeping top pressure is p ₁No longer give vent to anger the condensate mass M of record extraction up to the top _O0With natural gas volume V _G0

(5) the beginning water filling is for gas, and keeping rock core pressure is p ₁, inject formation water from the rock core top to rock core, when pressure reaches p ₂After stop water filling, close rock core top valve, stablize more than 4-6 hour, open this valve again and carry out blowdown, when pressure drops to p ₁And when no longer give vent to anger in the top, record rock core top produced gas volume V _G1, oil mass M _O1, i water filling obtains gas production V for behind the gas _G1, V _G2, V _G3..., V _Gi, oil production M _O1, M _O2, M _O3..., M _OiThereby, obtain through the condensate gross mass M of i water filling for the gas extraction _OtiWith natural gas cumulative volume V _Gti:

M _oti＝M _o1+M _o2+M _o3+…+M _oi

V _gti＝V _g1+V _g2+V _g3+…+V _gi；

(6) when rock core pressure reaches the gas reservoir abandonment pressure, close rock core top valve, open rock core bottom valve, pressure is reduced to atmospheric pressure gradually, emit all oil gas water in the rock core, get natural gas gas production V to the end _gAnd oily, water volume V _o, V _wThereby, obtain rock core gas reserves V _Gt:

V _gt＝V _g0+V _g1+V _g2+V _g3+…+V _gi+V _g+V _f1-V _o-V _w

Through condensate in place N in the computes rock core:

$N=\frac{V_{\mathrm{gt}}}{\mathrm{GOR}}{\mathrm{\ρ}}_o$

GOR is a condensate gas initial gas oil ratio in the formula,

ρ _oBe the density of ground condensate and water, g/ml;

(7) recovery ratio through the computes condensate is R _OiRecovery ratio R with natural gas _Gi:

$R_{\mathrm{oi}}=\underset{0}{\overset{i}{\mathrm{\Σ}}}{M}_{\mathrm{oi}}/N\×100\%$

$R_{\mathrm{gi}}=\underset{0}{\overset{i}{\mathrm{\Σ}}}{V}_{\mathrm{gi}}/V_{\mathrm{gt}}\×100\%.$