American Journal of Technology and Applied Sciences 
ISSN (E): 2832-1766        Volume 23, April - 2024                              

 

P a g e  | 50  www.americanjournal.org 

 

DETERMINING THE SKIN EFFECT BASED ON THE PRESSURE 

RECOVERY CURVE 
Norinov Fakhriyor Kurbanovich 

Abdirazakov Akmal Ibragimovich 

Karshi Engineering and Economic Institute, 

Karshi City, Republic of Uzbekistan 

E-mail; faxriyornorinov@gmail.com 

 

A B S T R A C T K E Y W O R D S 

This article presents some conclusions based on the results of studies 

in the well and the use of bottomhole conductivity, hydraulic 

conductivity and other properties of the reservoir to find the value of 

the skin effect, and at the same time taking into account the indicators 

of well No. 19 at the Shurchi field. 

 

Orizon, wells, bottom 

hole, testing, pressure, 

skin effect. oil, 

coefficient. 

 

Introduction  

The right and left sides of the equation are equivalent when there are no additional resistances in the 

near-wellbore zone, and their inequality indicates the difference between the hydraulic conductivity of 

the near-wellbore and remote zones, which, in the case of deterioration in the hydraulic conductivity 

of the near-wellbore zone, necessitates the cost of additional depression Δрz with a constant volume of 

product fil 

                                                  Δ𝑝z = Δ𝑝𝑡 − 𝑖 (lg 𝑡 + lg
2.25𝑥.

𝑟𝑐
),      

где Δр𝑡 − pressure increase during time t after the well is closed. Entering  
Δ𝑃𝑠

𝑖
= 𝑆, we obtain the 

equation for determining the skin effect:𝑆 =
Δ𝑝

𝑖𝑡
− lg 𝑡 − 𝑐,     

 c - correction for pressure loss on the well wall, which is calculated for known values of χ and rc using 

the formula C=lg⁡135x/(r_c2) or taken from the table. 1.1; t - duration of well shutdown, min. 

A positive value of the skin effect indicates the presence of additional filtration resistance in the 

bottomhole zone of the well, to overcome which a certain part of the depression Δp_s=iS is spent, 

which is used to estimate the productivity ratio ОП =
Δ𝑝𝑡−Δ𝑝𝑧

Δ𝑃𝑡
                     

However, depending on the condition of the bottomhole zone, the following options are possible. 

 

 

 

 

 



American Journal of Technology and Applied Sciences 
Volume 23, April - 2024 

 

 
P a g e  | 51  www.americanjournal.org 

 

Condition of the bottomhole zone……… kz < k kz > k kz = k 

Skin effect………………………………….. S>0 S<0 S=0 

Productivity ratios……………….. ОП<1 ОП>1 ОП=1 

Hydraulic conductivity ratio…………… ОГ>1 ОГ<1 ОГ=1 

 

Definition of skin effect and productivity relationship 

Determination of the state of the bottomhole zone and the quality of formation opening on the 

development of test results during the drilling of a well. 

Wells 19 Shurchi. Test interval 798-795 m. On December 10, 1967, using a formation tester, an influx 

of oil and gas mixture with a volume of 3 m3 was obtained in 80 minutes, which corresponds to a flow 

rate of 60 tons/day with a change in bottomhole pressure from 2 MPa to 5 MPa to a depth of 810 m. 

Additional data: oil density 875 kg/m3; volume factor 1.38; effective thickness of layers in the testing 

interval is 15 m; wellbore radius in the test interval is 0.140 m. 

  

   

Recovery schedule 

pressure in skB. 19 Shurchinskaya, built according to the Horner method (interval and tests 798-795 

m) 

Since the volume of inflow of oil, oil and gas is determined based on the increase in the liquid level in 

the well before closing to restore pressure, the volumetric coefficient is considered to be zero. The 

formula determines the skin effect. 

𝑆 =
𝑝пл − 𝑝3

𝑖
− lg 𝑇 − 𝑐, 



American Journal of Technology and Applied Sciences 
Volume 23, April - 2024 

 

 
P a g e  | 52  www.americanjournal.org 

 

where rpl is reservoir pressure, MPa; рз - bottomhole pressure at the end of the inflow period, MPa; T 

- duration of inflow (open period) before closing to restore pressure min. 

The correction factor c is determined from the table. 1.1, the value of which for 
𝑘ℎ

𝜇
= 24,9 ⋅ 10−11𝑀3/(∏𝑎 ⋅ 𝑐), rc= 0,098 м и hэф= 15 м equals 2,6. 

Then 

𝑆 =
19.3 − 15.7

0.46
− 1.8 − 1.6 = 3.4. 

Additional depression losses for skin effect value 

Δ𝑝𝑧 == 𝑖𝑆 = 0,46 × 3,4 = 1,56𝑀𝐼𝐼𝑎 

Productivity ratio 

W =
19.3 − 15.7 − 1.6

19.3 − 15.7
= 0.55. 

The results obtained indicate that the presence of skin effect in the near-wellbore zone leads to a 

decrease in its productivity by 45% 

 

Conclusion 

Above is the calculation of the skin effect of the productivity of the Shurchi field using indicators 

between the pressure recovery curve and the permeability of the well bottom. The results showed that 

the presence of the skin effect caused a significant decrease in the productivity of well No. 19 at the 

Shurchi field. 

 

References 

1. Проект пробной эксплуатации месторождения Шурчи. - Ташкент :  1964г. 

2. Мищенко И. Т. Скважинная добыча нефти. - М. : "Нефть и газ", 2003 

3. Мищенко И. Т. Расчеты при добыче нефти и газа. - М. : "Нефть и газ" , 2008. 

4. Юрчук А.М. Расчеты в добыче нефти. – М. : «Недра», 1979, 271с  

5.Абдиразаков А.И., Иботов О.К., Мавланов З.А. Анализ показателей разработки 

месторождения и практических расчетов // Universum: технические науки : электрон. научн. 

журн. 2020. 12(81). 

6. Абдиразаков А.И., Иботов О.К., Мавланов З.А. Анализ воздействие паротепловой обработки 

на основных показателей скважин // Universum: технические науки : электрон. научн. журн. 

2020. 12(81).