Academic Journal of Science and Technology 
ISSN: 2771-3032 | Vol. 10, No. 1, 2024 

 

311 

Adjustment	and	Application	of	Well	Test	Interpretation	
in	The	Development	of	W‐zone	of	Ji	Plateau	Oilfield	
Yajun Nan, Huarui Xu, Huiyang Li 

Xi’an Shiyou University, Xi’an 710065, China 

 

Abstract: Oilfield development well test is an important means to correctly understand the reservoir and improve the recovery 
rate, which is of great significance in slowing down the decreasing production of the oilfield and formulating an effective 
development plan. [1] Jiyuan oilfield W area of ultra-low permeability reservoir production accounted for a large proportion of 
the (52.1%), After the reservoir enters into the middle water content period, the contradiction of water-driven development is 
highlighted, and the difficulty of effective and stable production is increased, in order to achieve the whole process management 
of the development of the research area, and to enhance and improve the effect of reservoir development, By analyzing the test 
well interpretation results in the past three years and classifying the test well curves statistically with the actual field conditions, 
the test well interpretation model is optimized; at the same time, the multi-interpretation of the test well interpretation results is 
systematically analyzed, the causes of multi-interpretation are analyzed, and the test well interpretation model suitable for the 
ultra-low permeability reservoir is preferred, and ultimately, in conjunction with the history of the development of the reservoir, 
the dynamics of the reservoir is combined with the data from the secondary interpretation of the test wells to deepen the 
understanding of the dynamics of the reservoir. [2]. 

Keywords: Well test; ultra-low permeability reservoirs; multiplicity of solutions; well test interpretation models. 
 

1. Introductory 
Jiyuan oilfield W area well test interpretation work is 

carried out much, the results of well test interpretation deviate 
from the actual situation in the field, and cannot reflect the 
real situation of the formation. The main well test methods in 
the first three years include unstable well test (pressure 
recovery test, pressure landing test), stratification test, 
hydrostatic pressure test, spot test and other well test methods. 
In the past, there were many problems in the whole process of 
interpreting the test well data with Saphir software, from raw 
data acceptance to the selection of the interpretation model. 
In order to reflect the real situation of the reservoir, the test 
well data of the W zone of Ji Plateau Oilfield were interpreted 
with Swift software for the second time. In order to reflect the 
real situation of the reservoir, the secondary interpretation of 
the test well data of W zone of Ji Plateau Oilfield was carried 
out by Swift software. The solutions were proposed in the 
whole process from the acceptance of raw data, the input of 
basic parameters, the selection of the interpretation model and 
the diagnosis of the model, so that the results of the test well 
interpretation were closer to the real situation of the formation. 

2. Secondary Interpretation Model for 
Well Testing 

The results of well test interpretation can truly reflect the 
reservoir fluid seepage condition and formation physical 
parameters, and provide a reliable basis for the formulation of 
later development measures. [9] Therefore, the selection of 
the test well interpretation model is also an important work in 
the study of the oilfield to carry out the theoretical process, 
according to the test well interpretation model combined with 
the current situation of oilfield production, the theoretical 
research results used to solve the actual problems in the field, 
the oilfield development and production services of great 
significance. Through the analysis of 400 well test data in the 

study W area it is concluded that the study area is mainly 
dominated by the fracture model (60%), and there are four 
main types of interpretation models suitable for the study area, 
namely, the homogeneous model, the infinite inflow vertical 
fracture model, the composite model, and the finite inflow 
vertical fracture model. 

 
 

 
Figure 2-1. Well test interpretation model 

 
Stage division of the test well interpretation model: Stage Ⅰ 

is called the renewal section, which refers to the stage when 
the oil flow flows into the borehole after the well is shut in, 
and the pressure and inverse are combined into one, and this 
stage is also called the wellbore storage section, and the larger 
the wellbore storage coefficient is, the longer the duration of 
this section is. Reflects the pressure change of the fluid being 
compressed process in the wellbore when the pressure is 
restored during the early shut-in of the test. Because in the 
early stage of well shut-in, although the wellhead is shut-in, 
the formation fluids far downhole continue to flow towards 
the wellbore, and these fluids enter the wellbore, causing the 
fluids in the wellbore to be compressed and re-accumulating 
elastic energy is pressure build-up. Stage Ⅰ includes the pure 



 

312 

well storage effect stage and the partial well storage effect 
stage, while the latter reflects both the pressure in the 
wellbore and the pressure change of the formation near the 
bottom of the well, so the contamination and blockage of the 
formation at the bottom of the well, and the perfection of the 
well, etc., directly affects the length of its action time. Based 
on the shape of the curve at this stage it is possible to make a 
qualitative judgement on the perfection and clogging of the 
well. [3] Phase II is the transition phase. The pressure shows 
a smooth transition, the derivative appears to peak and then 
slopes downward, the peak height depends on the value of the 
combination of epidermal factors CDe2S, the larger the value 
of CDe2S, the higher the peak, and the more delayed the 
appearance of the peak. Stage III radial flow section, when 
the pressure in the wellbore reaches a certain value, the 
formation near the bottom of the well begins to recover, and 
the test gradually transitions from a partial well storage effect 
to the end of the well storage effect, and a planar radial flow 
stage of the formation occurs. This section satisfies the 
pressure recovery equation and is an effective semi-
logarithmic straight line section whose slope magnitude is 
directly related to the seepage characteristics of the formation. 

[4] A good permeability of the formation results in a small 
slope and vice versa. When the formation at the bottom of the 
well produces lateral inhomogeneity due to phase change, the 
slope of the semi-logarithmic straight line changes, and the 
slope changes from small to large, indicating that the 
permeability of the formation has changed from good to poor, 
and vice versa, the permeability of the formation has changed 
from poor to good. Stage Ⅳ is called the boundary influence 
section, the early and late appearance of this section and the 
test well drainage and drive area tubing, drainage and drive 

area is large, the boundary influence section appeared late, 
otherwise appeared early. [5] Theoretically, the boundary 
influence section reflects the pressure characteristics of the 
apparent phase, so that the pressure tends to a constant value 
and the curve is asymptotically horizontal. If it is a closed 
reservoir boundary, the semi-logarithmic straight line will 
buck. If it is a new well on production next to the test well and 
the formation is well connected, the test well pressure will 
drop due to inter-well interference. 

3. Analysis of Secondary Interpretation 
of Well Testing 

In this paper, through the secondary interpretation of 400 
well test data in the study area with Swift well test software, 
measures are given to potential wells through well test 
interpretation model fitting and model analysis. Firstly, the 
fitting of well test interpretation model is carried out to 
analyze the reasonableness of the data of one well test 
interpretation, preprocess the data, select the model through 
the dynamic data of reservoir development, and analyze the 
parameters such as skin coefficient, permeability, well storage 
coefficient, formation pressure and so on to end the fitting 
when they are suitable values, if the parameters are 
particularly far from the formation characteristics, it is 
necessary to re-fit the model. Test well interpretation model 
analysis, according to the test well interpretation of fracture 
half-length, formation pressure and other parameters and 
production dynamic data through horizontal and vertical 
comparison of the study area seepage law, water repulsion law, 
pressure repulsion analysis of the law, to provide a theoretical 
basis for the selection of wells for the measures. [12]  

 

 
Figure 3-1. Flow of analysis of secondary interpretation of well test 

 
In this paper, through the statistics of one and two test well 

interpretation model percentage, the statistical results show 
that the primary test well interpretation is mainly based on the 
homogeneous model (72%), according to the analysis of the 
reservoir production characteristics are mainly based on the 
fracture linear flow primary test well interpretation does not 

meet the real situation of the formation. The coverage rate of 
secondary well test interpretation reaches 89%, and the 
proportion of secondary well test interpretation model in W 
area is 60% for fracture model, 21% for homogeneous model 
and 19% for composite model. 

 



313 

Figure 3-2 Comparison of the results of primary and secondary interpretation of test wells 

W zone is mainly dominated by infinite conduction vertical 
fracture model, followed by finite conduction vertical fracture 
model, indicating that fractures are commonly developed in 
reservoir reservoirs. Layer-by-layer analysis as a whole is 
dominated by homogeneous model, composite model and 

infinite conduction vertical fracture model, and there are 
differences in different layers, with homogeneous and infinite 
conduction vertical fracture model dominating in Chang 6 and 
Chang 8, and no obvious difference in Chang 4+5. 

Figure 3-3. Interpretation model distribution of test wells (sub-reservoir, sub-layer) 

4. Application of the Results of The
Secondary Interpretation of Well
Tests

Through the secondary interpretation of 400 wells test well 

data, in-depth excavation of reservoir geological data, 
combined with production dynamics to analyze the pattern of 
change of seepage flow in oil and water wells, to optimize the 
single-well development plan, and to provide a theoretical 
basis for the selection of pressure measurement and selection 
of wells. 



 

314 

4.1. Polymer Microspheres Integral Tuning 
Drive 

According to the results of the second interpretation of the 
test wells, the comprehensive management idea of "injection-
drive-extraction" system engineering in the early stage of W 

area, it is recommended to support the dissection and drive, 
the specific approach is "PEG-1 gel single well dissection + 
regional polymer microsphere drive". Among them, 8 single 
wells are mainly carried out in the east, and 30 polymer 
microsphere drives are implemented in the centre in 1/3 ratio. 

 
Table 4-1. Block W PEG-1 Gel Conditioning Treatment Wells 

serial 
number 

pound sign Well group development conflicts 
Purpose of 

implementation 

anatomical and driving 
parameters 

PEG-1: 
grain size: 100-300μm 

Injection concentration: 
0.3% 

injection volume: 2000m3 
Injection Volume: 1.0-

1.2m3/h 
Microsphere: 50nm 
Concentration: 0.1% 

injection volume: 6000m³ 
Injection volume: Equal 

geological injection 

1 T92-90 
Entering the medium water-bearing stage, 

accelerating the rate of rise of water content 
water control and 
oil stabilization 

2 T86-94 High water content stage, low extraction 
Reduced water 

content 

3 T94-90 
Strong vertical non-homogeneity, uneven profiles, 

and well flooding in well group oil wells 
water control and 
oil stabilization 

4 T92-92 
Well group wells flooded with uneven suction 

profiles 
water control and 
oil stabilization 

5 T90-92 
Strong vertical non-homogeneity, uneven profiles, 

and well flooding in well group oil wells 
water control and 
oil stabilization 

6 T90-90 
Entering the medium water-bearing stage, 

accelerating the rate of rise of water content 
water control and 
oil stabilization 

7 T88-92 Strong vertical inhomogeneity and uneven profiles 
improved water 

drive 

8 T86-94 
Strong vertical non-homogeneity, uneven profiles, 

uneven water injection effects 
Scaling up for 

results 

Subtotal (8 ports)    

 
After the treatment, the average daily oil increase of a 

single well is 0.55t, and after the implementation of PEG-1 
gel dissection measures, the seepage condition of the 
reservoir has been significantly improved, the water-control 
capacity has been significantly strengthened, and the oil 
production capacity has been greatly increased. 

4.2. Evaluating the effectiveness of single-well 
measures in measure wells 

According to the results of the second interpretation of the 

test wells and the production dynamic data, the 18 oil 
recovery wells in the W zone were divided into three 
categories, A, B and C, and measures were recommended, and 
a total of 18 potential wells were mapped out. The statistical 
interpretation results showed that the differential pressure and 
derivative curves were mostly glued together, and the 
reservoir properties were poor, the thickness of the sand body 
was large, and the fracture was developed, and measures such 
as repetitive fracturing, temporary plugging of the fracture, 
and oxidization were adopted. 

 
Table 4-2. Well Selection and Recommendations for Measures in Zone W 

classify 
curve 

characteristic 
Corresponding 
well number 

Reservoir 
characteristics 

dynamic 
characteristic 

Reservoir characteristics 
Recommendations 

for measures 

Category 
A 

Test well 
curves 

characterized 
by shanks, 
presence of 

fracture 
closure 

T98-89 
T89-100 
T82-85 

T56-101 

Poor storage 
materiality 

Medium and 
high 

pressure low 
yield 

Sand body thickness, good 
connectivity, high formation 

pressure, reservoir micro 
fracture development, 

imperfect injection and 
extraction, strong non-

homogeneity 

Repeat fracturing 

Category 
B 

No humping 
at the end of 
well storage 

J85-102T95-96 
T93-96T92-95 
T91-88T84-95 

T83-89T59-101 

Poor storage 
materiality 

high 
pressure, low 

yield 

Sand body thickness is large, 
non-homogeneous strong 

stratigraphic pressure is high, 
multi-directional see water 

temporary 
plugging of 

fracking 

Category 
C 

Humping at 
the end of 

well storage 

T99-98 
T97-85 
T85-94 
T76-93 

T57-103 

Presence of 
inter-well 

interference 

high 
pressure, low 

yield 

Sand body thickness is large, 
single sand body is complex, 

conventional acidification 
measures body fluid effect is 

poor 

acidification 

 



 

315 

 

5. Summary 
In this paper, through the Swift well test software fitting 

analysis, the reservoir seepage model is dominated by fracture 
linear flow, the oil well reservoir model mainly shows single 
direction linear flow characteristics, the reservoir overall 
mobility is poor, and the pre-test well interpretation PPD 
curve is mostly glued together. According to the classification 
of oil and water wells in the study area of test well secondary 
interpretation curve morphology, there exists the 
phenomenon of shutting down wells without radial flow in W 
area, and it is recommended to extend the time of shutting 
down wells. For the fracture type has multi-well interference, 
fracture linear flow, low speed non-Darcy characteristics 
obvious oil wells corresponding to water injection wells 
combined with chemical dissection, improve the efficiency of 
longitudinal upstream water oil drive; homogeneous, 
impermeable model, water injection wells reservoir model to 
multi-well interference is dominated by multi-well model in 
the area more indicates that the area by the strong body of 
water neighboring wells have a greater impact on the 
production system of the multiple wells interfere more. 

Generally speaking, the interpretation of the second test 
well is more reasonable than that of the first test well, and the 
interpretation results are more in line with the real condition 
of the formation. 

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