Energy and Power Engineering, 2013, 5, 1508-1511
doi:10.4236/epe.2013.54B285 Published Online July 2013 (http://www.scirp.org/journal/epe)
Utilizing NMR Mud Logging Technology To Measure
Reservoir Fundamental Parameters in Well Site
Yingzhao Zheng1,2, Dehui Wan2, Muhammad Ayaz2, Caiqin Ma3
1School of Energy Resources, China University of Geosciences, Beijing, 100083, China
2Mud Logging International Department, Great wall drilling company, Beijing, 100101, China
3Beijing Winfield Petroleum Technology Company, Beijing, 100083, Chin
Received 2013
ABSTRACT
Nuclear Magnetic Resonance mud logging technology (NMR mud logging) is a new mud logging technology. Mainly
applies the CPMG（Carr-Purcell-Meiboom-Gill）pulse sequence to measure transverse relaxation time (T2) of the fluid.
NMR mud logging can measure drill cutting, core and sidewall core in the well site, also according to the experiment
results, the sample type and size has little effect to analysis result. Through NMR logging, we can obtain several petro-
physical parameters such as total porosity, effective porosity, permeability, oil saturation, water saturation, movable
fluid saturation, movable oil saturation, movable water saturation, irreducible fluid saturation, irreducible oil saturation,
irreducible water saturation, pore size and distribution in rock samples, etc. NMR mud logging has been used nearly 10
years in China, Sudan, Kazakhstan, etc. it plays an important role in the interpretation and evaluation of reservoir and its
fluids.
Keywords: NMR Mud Logging; Porosity; Oil Saturation; Reservoir Fluids; T2 Cutoff; Spectrum
1. Introduction
Faster drilling speed and higher drilling cost (especially
offshore) dictate reducing cost and decreasing the time
for reservoir evaluation. Simultaneously, it is necessary
to ensure the reliability of the results of such evaluation.
A number of techniques which analyze drill cuttings at
the well site for quantitative formation evaluation have
been developed, among them，NMR mud logging is the
best to evaluate the reservoir.
Porosity, permeability and oil saturation are funda-
mental parameters for reservoir evaluation. In order to
get these petrophysical parameters of the reservoir, we
usually analyze the core samples in the laboratory, but
that need a long period and cost a lot. As the drilling cost
increase, there is an urgent requirement to measure fun-
damental parameters of the reservoir in the exploration
and production of oil and gas field, especially that of low
porosity and low permeability reservoir and hiding res-
ervoir.
NMR mud logging technology has implemented the
transfer from the lab to the well drilling field for the
petrophysical analysis of the conventional core, and ex-
panded the analysis object from conventional core to the
cutting and sidewall core.
NMR mud logging technology utilizes hydrogen
atomic nucleus (1H) rich in the formation fluid (oil, gas
and water) to obtain the petrophysical parameter such as
the porosity, permeability, fluid saturation, fluid property,
movable fluid and irreducible fluid [1-4]. This technol-
ogy has been widely applied to the evaluation of reser-
voir and its fluids.
It has many merits, such as little amount of sample
used, fast analysis speed, several parameters from one
sample, high accuracy, high continuity and analysis
while drilling. It has significance in classifying and
evaluating effective reservoir, instructing drilling on site
and providing data for the well completion discussion
and drilling completion test, so it has great role in the
exploration and the production of oil and natural gas.
In 2001, A portable NMR rock sample analyzer was
developed by NMR Laboratory of RIPED (Research In-
stitute of Petroleum Exploration and Development, Pet-
rochina), China. The researchers performed much basic
work on the analysis of core and cuttings, confirmed the
feasibility of NMR analysis of cuttings, conducted the
field test of the new NMR logging technology in several
Chinese oilfields, and successfully solved many critical
problems. NMR mud logging has exerted important role
in the exploration and production of oil and gas field.

Y. Z. ZHENG ET AL. 1509
2. NMR Mud Logging Methods and
Parameters
NMR mud logging unit (use RecCore 2500 unit as an
example, the picture is show in Figure 1) use one big
probe (25mm in diameter) and one small (10mm in di-
ameter) probe. The big probe can used to analyze the
samples of side wall core and conventional core; the
small probe can be used to analyze cutting samples.
2.1. NMR T2 Spectrum and T2 Cutoff Value
After the samples are well treated, they can be analyzed.
NMR mud logging first obtains the echo string, which
can be mathematically inversed to get T2 spectrum. Fig-
ure 2 shows the NMR T2 spectrum of a sample. The
x-coordinate represent the T2 relaxation time, the ordi-
nate represent amplitude, which is in direct proportion to
the fluid amount with certain T2 relaxation time [5].
As NMR T2 relaxation time reflects the interface
strength of the pore solid surface to the fluids it con-
tained. The fluid with more T2 relaxation time (fluids in
big pore does not contact closely with solid surface) is
the movable fluid or free fluid. The fluid with less T2
relaxation time (fluids in small pore contact closely with
solid surface) is the irreducible fluid. The boundary be-
tween the movable fluid and the irreducible fluid in T2
spectrum is called as movable fluid T2 cutoff value
(shown as Figure 3). The T2 cutoff value vary from
fields to fields, but mainly distributes between 8~30ms. It
can be accurately measured by the indoor centrifugal
method [6].
Figure 1. NMR mud logging unit.
0
10
20
30
40
50
60
70
80
90
100
0.1110100 1000
T2 relaxation time(ms)
amplitude
Frequency distribution
Cumulative distribution
Figure 2: NMR mud logging T2 spectrum.
The main NMR measurement parameters:
Porosity (Φ)
Permeability (K)
Oil Saturation (So)
Free Fluid Saturation (Sm)
Free Water Saturation (Swm)
Irreducible Water Saturation (Swi)
2.2. NMR Porosity Measuring Principle and
Method
The NMR signal amplitude is proportional to the fluid
amount contained in rock sample, when the samples are
fully saturated with fluids (water or oil), we can measure
the total porosity. When the samples are centrifuged, all
the movable fluid will be removed, only the irreducible
fluid (clay bound fluid) are remained in the sample, so
the effective porosity can be measured.
NMR porosity measuring steps are as follows: Firstly,
calibrate the NMR mud logging unit, establish the linear
relationship between the NMR signal amplitude and the
porosity (shown as Figure 4); Then measure NMR sam-
ple, get sample NMR signal amplitude；At last, substitute
the signal amplitude into sample porosity.
Φ e
Clay
b
ound
fluid
Capillary
b
ound
fluid
Free
fluid
Pore size
T2 cutoff T2
Φ
Figure 3. Relationship between porosity and effective po-
rosity.
y = 0.2917x + 2.418
R2 = 0.9999
0
6
12
18
24
30
0 20406080100
NMR signal amplitude
Conventional porosity
Figure 4. The linear relationship between NMR signal am-
plitude and the porosity.

Y. Z. ZHENG ET AL.
1510
2.3. NMR Saturation Measuring Principle and
Method
In order to measure oil saturation, the sample needs to be
analyzed twice. Firstly, analyze the sample under the
condition that the pore space is fully saturated by water,
and we measure the total signal of oil and water; sec-
ondly, we dip that sample in manganese Mncl2 (concen-
tration 10000 mg/l), which is a paramagnetic substance
to eliminate water signal. Then, we analyze that Mncl2
saturated sample to obtain oil signal (Figure 5).
When we get both of the T2 spectrums like Figure 5,
we can derive the oil saturation by following calculation.
2max
2max
T
o
0
oT
ow
0
A(t)dt
S1
A(t)dt


00%
where, So is oil saturation, Aow represents oil and water
signal amplitude, Ao represents oil signal amplitude.
Meanwhile, other parameters, such as movable oil
saturation, irreducible oil saturation, movable water
saturation and irreducible water saturation (Xiao, et al.,
2000) can be got.
2.4. NMR Permeability Calculating Principle
and Method
NMR permeability can be calculated by an empirical
model--Timmur-Coates model.
24 nmr
nmr )
Sm-1
Sm
()
C
(K 

where, Knmr—NMR permeability, 10-3µm2;
Фnmr-- NMR porosity, % ;
Sm--Free Fluid Saturation, %;
C—regional coefficient, Changes with strata, deter-
mined by core analysis.
2.5. Pore Structure Evaluation
NMR T2 spectrum depend on topology of pores (shape
and size); In large pores, T2 value are longer, as more
nuclei are available in the pores; In small pores, T2 value
are short. The distribution of T2 spectrum can range from
Figure 5. T2 spectrum separation of oil and wate r .
1 to 10,000 ms. Therefore, T2 is in direct proportion to
pore throat radius. Generally, wider distribution range of
T2 spectrum and lower amplitudes represent poor sorting
of pores, and smaller pore throat (He et al., 2005). In
addition, higher amplitudes for higher T2 cutoff values
represent larger pores, and thus the reservoir formation is
potentially better.
Different samples have different pore structure, and
the same for the lithology. These differences lead to the
difference of T2 differential curves and cumulative
curves. Therefore, the size, sort and distribution of pore
throats can be evaluated according to T2 curves of satu-
rated samples.
3. NMR Mud Logging Application
By comprehensive use of NMR mud logging data, the
geologists can quickly evaluate the reservoir and its flu-
ids in well site, which will be very useful for the discus-
sion of well completion, perforation and well test [7,8].
NMR mud logging technology has been widely used
more than 10 years around the world by Chinese mud
logging companies. A few thousands of cuttings and core
samples have been measured by the NMR mud logging
system and excellent application results of this technol-
ogy have been achieved. Now, it plays an important role
in the interpretation and evaluation of reservoir and its
fluids.
3.1. The Application of NMR mud Logging in
BA-1, Nanyang oil Field, China
Ba-1 is a wildcat well, located in Henan province, China.
NMR mud logging analyzed 13 samples in the interval
4044-4047m, which is best fluorescence show interval of
the well.
In that interval，the lothology is fine sandstone with
good oil shows. For chromatograph logging, the maxim
total gas is 6.9%, also the trip gas are very strong, even
lasts 25min.Wireline logging interpreted this interval as
pay zone.
NMR logging result are as follows: Porosity: 7.05%-8.
20%; Permeability:0. 01-0.18x10-3μm2; Oil Saturation:
5.47%-8.98%; Free Fluid Saturation: 26.01%-33. 84%;
Free Water Saturation: 24.06%-30.21%; Irreducible Wa-
ter Saturation: 61.25-70. 47%; NMR interpreted this in-
terval as dry zone.
This interval was tested, but the maxim output is only
0.51 t/d. NMR mud logging interpretation coincides with
test result.
3.2. The Application of NMR Logging
Technology in a Well of Jilin oil Field, China
In a well of Jilin oil field, NMR mud logging analyzed
47cuttings samples. Each cuttings sample obtained the

Y. Z. ZHENG ET AL.
1511
Table 1. Comparison between NMR mud logging result and
well test result.
NMR mud logging result
(average value) Test result (m3/d)
Depth
(m)
Sample
No. Φ
(%)
K
(mD)
Sm
(%)
So
(%) Oil Water
1970
-1973 3 10.74 1.99 43.2 35.2 6.4 5.7
2379
-2383 3 7.78 0.29 35.2 5.01 0.00411.4
porosity, the permeability, movable fluid saturation and
oil saturation and so on.
At the interval 1970-1973m, the porosity, permeability,
movable fluid saturation and oil saturation obtained by
NMR logging are all higher, but the movable fluid satu-
ration is 8% higher than the oil saturation (shown in Ta-
ble 1). It is estimated that there were certain amount of
movable water in the formation. Therefore, NMR log-
ging interpreted this interval as oil with water. NMR mud
logging interpretation coincides with test result.
At the interval 2379-2383m, the movable fluid satura-
tion obtained by NMR logging is higher, but the oil satu-
ration is very low, thus it can be estimated that the oil
content in the formation is very small, the movable water
is higher, so this layer is interpreted as water zone. The
cuttings NMR logging explanatory result also coincides
well with oil test result.
5. Conclusions and Suggestion
A. NMR mud logging can provide porosity, permeability,
oil saturation, movable fluid saturation, irreducible water
saturation, movable water saturation with high precision
from rock sample. It can provide reliable data for the
well completion discussion and drilling completion test,
so it plays great role in the oil and gas exploration and
production.
B. NMR mud logging can analyze the rock sample
(core, cuttings, sidewall coring) on the well site.
C. In addition to evaluating petrophysical parameters,
NMR mud logging can be used to classify and evaluate
the pay zone.
D. NMR mud logging tests have been carried out in
various oil fields in China, Sudan and Kazakhstan; The
results show that NMR mud logging technology can pro-
vide reliable petrophysical parameters timely and accu-
rately.
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