Composite Dan Future IPR - 2010

INFLOW PERFORMANCE RELATIONSHIP COMPOSITE IPR

LOGO

LOGO

Composite IPR (1) 



Nearly all producing formations are stratified to some extent. This means that the vertical borehole in the production zone has different layers having different reservoir pressures, permeabilities, and producing fluids. If it is assumed that there are no other communication between these formations (other than the wellbore), the production will come mainly from the t he higher permeability layers. q1+q2+q3

Pr1, k1,..

q1 q2 q3

Pr2, k2,.. Pr3, k3,.. 2

Composite IPR (2)

LOGO

 As

the well’s rate of production is gradually increased, the less consolidated layers will begin to produce one by one (at progressively lower GOR), and so the overall ratio of production (q 1 : q2 : q3) will fall as the rate is increased. (q1+q2+q3)>>> Pwf > GOR total >> q1 q2 q3

4

Composite IPR (4) 

LOGO

Thus, it is to be expected that a well producing from a stratified formation will exhibit a minimum GOR as the rate of production is increased.

q1+q2+q3> > GOR total > > q1 q2 q3

5

Composite IPR (5) 

LOGO

One of the major concerns in a multiplayer system is that interlayer cross-flow may occur if reservoir fluids are produced from commingled layers that have unequal initial pressures. This cross-flow greatly affects the composite IPR of the well, which may result in an optimistic estimate of production rate from the commingled layers. q1+q 2+q 3>> GORtotal >> q1 q2 q3

6

Composite IPR (6)

LOGO

 El-Banbi

and Wattenbarger (1996, 1997) investigated productivity of commingled gas reservoirs based on history matching to production data. However, no information was given in the papers regarding generation of IPR curves.

7

Composite IPR (7)

q 1+ q2+ q3> > GOR total > >

q1

LOGO

•

Pseudo –steady-state flow prevails in all the reservoir layers.

•

Fluids from/into all the layers have similar properties.

•

Pressure losses in the wellbore sections between layers are negligible (these pressure losses are considered in Chapter 6 where multilateral wells are addressed).

•

The IPR of individual layers is known.

q2 q3

8

PENGEMBANGAN PERSAMAAN COMPOSITE IPR

LOGO

On the basis of Assumption 1, under steady-flow conditions, the principle of material balance dictates net mass flow rate from layers to the well = mass flow rate at well head 

or

9

PENGEMBANGAN PERSAMAAN COMPOSITE IPR

LOGO

Fluid flow from wellbore to reservoir is indicated by negative q i Using Assumption 2 and ignoring density change from bottom hole to well head, Eq. (3.36) degenerates to

10

Single-Phase Liquid Flow

LOGO

The reservoir Pressure is above the Bubble Point Pressure  The flowing bottom hole pressure also above the Bubble Point pressure 

 J*i

is the productivity index of layer I



IPR Equation for composite reservoirs and single phase

11

Maximum Production Rate

LOGO

For a single layer formation, Qmax is determine at Pwf = 0  It is different for composite formations  Each formation has different values of Qmax, but should have the same bottom hole pressure  It should be borne in mind that Pwfo is a dynamic bottomhole pressure because of cross-flow between layers. 

12

Two-Phase Flow Composite IPR

LOGO

 Developed

based on Vogel’s IPR Curve

 Composite

TwoPhase IPR Curve

 Well’s

Maximum Flow

Rate  The

flowing bottom hole pressure at Qmax 13

Two Phase IPR  – Pr > Pb

LOGO

14

Case Study (1)

LOGO

15

Case Study (2)

LOGO

16

Case Study (3)

LOGO

The composite IPR for Group 1 (D3 and D4) is the same as shown in Fig. 3.15 because these two layers were the commingle-tested. Composite IPRs of Group 2 and Group 3 are plotted in Figs. 3.17 and 3.18. Table 3.2 compares production rates read from Figs. 3.16, 3.17, and 3.18 at some pressures. This comparison indicates that significant production from Group 1 can be achieved at bottom-hole pressures higher than 2658 psi, while Group 2 and Group 3 are shut-in. A significant production from Group 1 and Group 2 can be achieved at bottomhole pressures higher than 2,625 psi while Group 3 is shutin. The grouped-layer production will remain beneficial until bottom-hole pressure is dropped to below 2,335 psi where Group 3 can be open for production. 17

LOGO

FUTURE IPR CURVES PERAMALAN KURVA IPR Np meningkat, P-r turun, maka Productivity Index turun (?)

18

Persamaan Aliran Dua Fasa

LOGO

Dinyatakan sebagai Fungsi tekanan So = f(P) Kro sebagai fungsi saturasi minyak

Berubah thd Waktu Dan Tekanan J dipengaruhi oleh kro /  oBo 19

Persamaan Aliran Dua Fasa

LOGO

 Perubahan

Kurva IPR di waktu mendatang ditunjukkan oleh perubahan slope, yang ditunjukkan oleh perubahan productivity index, J.  Untuk kondisi aliran 2 fasa, untuk setiap kurva IPR harga productivity index dinyatakan sebagai dq/dPwf = J

20

Perubahan Productivity Index (1)

LOGO

21

Perubahan Productivity Index (2) 



Muskat menyatakan bahwa perbandingan Productiviy Index pada dua waktu produksi yang berbeda dapat dinyatakan sebagai perbandingan: Productivity Index didefinisikan sebagai slope dari kurva IPR

 J 1  J 2

LOGO

  k ro     m o Bo     1    k ro      m o Bo   2

 J 

 dq  dPwf  22

Peramalan IPR

LOGO

Productivity Index, (dq/dPwf ) yang merupakan turunan dari persamaan Vogel adalah sebagai berikut:

 J  p

*

1 .8Q o max  P r

Subscript “p” menyatakan kondisi saat ini (present condition) Berdasarkan persamaan aliran 2 fasa, perbandingan productivity index pada kondisi saat ini dan yang akan datang, dinyatakan:

23

Peramalan IPR

LOGO

Berdasarkan hasil turunan productivity index, maka dapat ditentukan Laju Produksi Minyak Maksimum untuk waktu produksi mendatang :

24

LOGO

Persamaan Fetkovich





Asumsi bahwa hubungan antara kro/ oBo terhadap tekanan adalah linier, sehingga perbandingan kro/ oBo pada dua harga tekanan sama dengan perbandingan tekanannya Dengan demikian perbandingan productivity index dapat dinyatakan sebagai

 k ro  B o

 o

 P r

 P ri

 k ro  B o

 o

 P r

 P ri

 J 1

 P r 1

 J  2

 P r 2

25

LOGO

Persamaan Fetkovich

 2  rf 

q o

 J  Pr  f   P

 J  Pri

 P ri

 J  Pr f 

 P rf 

Harga JPri dan n diperoleh dari data test isochronal pada Pri

 2  n wf 

P

 J  Pr  f 

Dengan anggapan bahwa J dan n tidak berubah

 J  Pri

q o

 P rf   P ri

 J  Pr i

 P rf   P ri

 2  rf 

 P

 2  n wf 

P

26

Persamaan Fetkovich 

LOGO

Jika harga “n” pada persamaan Fetkovich dianggap berharga 1.0, maka perbandingan antara laju produksi maksimum pada dua harga tekanan reservoir yang berbeda dapat dinyatakan sebagai:

Q o max 2

 P r 2

Q o max 1

 P r 1

Q o max  f 

Q o max i

 3

 P rf 

 3

 P ri

27

Persamaan Peramalan IPR - PS

LOGO

 3

q o

7  .08 10  kh ln

 re  rw

 m  P r

 m Pwf 

0 . 5 S

Pada Pwf  = 0 maka Qo,max:

Perbandingan Qomax awal terhadap Qomax yang akan datang:

 3

Q o max

7  .08 10  kh ln

 re  rw

0 . 5

 m P r

S

Q o max  f 

 m  P rf 

Q o max i

 m  P ri 28

LOGO

Persamaan Peramalan IPR - PS API > 40  m  P rf   m  P ri

 P rf  0 .015215exp  4 .152343  P ri

Q o max  f 

API < 40  m  P rf   m  P ri

Q o max i

 m  P rf   m  P ri

 P rf  0 .033210 exp  3 . 429922  P ri

Persamaan IPR “PS”

29

LOGO

Persamaan IPR PS

 a n

 c 2 S

 c1e

 P D

 c 4 S

 c 3 e

an

c 1

c 2

c 3

c 4

a 1

0.1829220

-0.3644380

0.8145410

-0.0558730

a 2

-1.4769500

-0.4566320

1.6462460

-0.4423060

a 3

-2.1492740

-0.1959760

2.2892420

-0.2203330

a 4

-0.0217831

0.0882860

-0.2603850

-0.2108010

a 5 

-0.5524470

-0.0324490

-0.5832420

-0.3069620

 Pwf   P r

30