Table of Content

11 April 2016, Volume 38 Issue 2

Previous Issue    Next Issue

Geochemical Characteristics of Hydrocarbon Source Rocks and#br# Oil-source Correlation of Kongdian Formation，Weibei Depression

SONG Lailiang1*, LIU Hua2, XU Haoqing1, LI Zhensheng2, WANG Xin2

2016, 38(2):  1-10.  DOI: 10.11885/j.issn.1674-5086.2014.03.02.02

Asbtract ( 305 )   HTML   PDF (860KB) ( 728 )  

References | Related Articles | Metrics

In order to identify distribution of effective source rocks and oil-gas generated by the effective source rocks in
Weibei Depression，some geochemical testing technologies，such as saturated hydrocarbon chromatography and chromatography–
mass spectrometry，are used to analyze the geochemical characteristic of source rocks in Kongdian Formation and space
corresponding relation of source-pool. Studies show that source rocks in Kongdian Formation are the important source of oil
and gas，with highest abundance of organic matter and best quality in upper 2nd member of Kongdian Formation，followed by
central and lower 2nd member of Kongdian Formation. Among each member of Kongdian Formation exist significant differences
in gammacerane content，ratio of pristine/ phytane and maturity. Oil-source correlation shows that crude oil found in
superficial layer (1st member of Kongdian Formation，upper 2nd member of Kongdian Formation) come from source rocks of
upper 2nd member of Kongdian Formation in northern sag，and that crude oil in central 2nd member of Kongdian Formation or
3rd member of Kongdian Formation come from source rocks of central 2nd member of Kongdian Formation in northern sag，
and oil generated by lower 2nd member of Kongdian Formation mainly accumulate near the source rocks.

The Formation Characteristics and Exploration Potential of Tight Oil in#br# Erlian Basin

WANG Jian1，2*, KONG Qingming2, DONG Xiongying2

2016, 38(2):  11-19.  DOI: 10.11885/j.issn.1674-5086.2014.04.15.05

Asbtract ( 257 )   HTML   PDF (922KB) ( 606 )  

References | Related Articles | Metrics

Reservoirs in Erlian Basin are generally with low porosity and low permeability. Reservoir in the special lithologic
section and tight glutenite segment in the trough area and tectonic wings under the top of K1bt1 and K1ba is particularly dense
with air permeability less than 0.5 mD. Two types of high-quality source rocks characteristic of special lithology containing a
cloud of gray matter and clayey lacustrine mudstones developed under the top of K1bt1 and K1ba. Hydrocarbon source rock
and tight reservoir are distributed as one or interbedded layers，which is favorable for hydrocarbon migration and accumulation.
Tight reservoir has a complex pore structure，and is characteristic of low production and low pressure. With high dolomite
content and brittleness，special lithologic reservoir is of good oil-bearing and physical properties，and is favorable for fracturing.
Although a single depression is small in size，but the whole reservoir is of large scale. Predicted by oil and gas resources，tight
oil resources amount is nearly one billion. The exploration work in the future should be focused on both tight oil and lithologic
reservoirs.

The Structural Control Effect on Petroleum Accumulation Elements in#br# Southern Apennine Region

LI Quan1*, DU Xiangdong1, KANG Hongquan1, LI Jinbo2, XIA Shiqiang3

2016, 38(2):  20-28.  DOI: 10.11885/j.issn.1674-5086.2014.04.10.03

Asbtract ( 330 )   HTML   PDF (1451KB) ( 529 )  

References | Related Articles | Metrics

The complex structural condition in the Southern Apennine region of Italy results in poor seismic imaging quality，
great difficulty in defining traps，and unclear character of petroleum entrapment. We believe that the structural evolution controls
the distribution of high quality source rocks. The stable structural environment plays a constructive role in the development of
source rocks. The intense structural evolution plays an inhibition role in the distribution and development of source rocks. The
structural belt controls the type of reservoirs，traps and the distribution pattern. The primary reservoir in the thrust fold belt
is Cretaceous carbonatite；the primary reservoir in the internal foredeep belt is turbidite sandstones of Pliocene–Pleistocene；
the primary reservoir in the external foredeep belt is Pliocene turbidite sandstones and Miocene carbonatite，and the primary
reservoir in the forebulge belt is Miocene–Cretaceous carbonatite. The structural paleogeography controls the distribution of
petroleum systems. During the syn-rift stage in Mesozoic，the distribution pattern of paleo-uplift and depression controlled the
oil and associated gas. During the collision stage in Cenozoic，the rapid subsidence of foredeep belt controlled the thermorgenic
gas system. The biogas system migrated outward gradually along with the migration of depocenter in foreland basin during
Quaternary.

An Analysis of Reservoir Characteristics and Controlling Factors#br# of Jurassic Da′anzhai Section in Langzhong Nanbu Area

ZHANG Qi1，2*, PENG Jun1

2016, 38(2):  29-38.  DOI: 10.11885/j.issn.1674-5086.2015.10.10.03

Asbtract ( 422 )   HTML   PDF (695KB) ( 890 )  

References | Related Articles | Metrics

We carried out researches on reservoir characteristics and controlling factors of reservoir development of Jurassic
artesian group Da′anzhai section according to theories and technical methods of sedimentary rock，reservoir geology，logging
geology，and by using data of drilling，logging，cores，well logs and indoor test analysis，etc. The results showed thatrock structure
components in the reservoir of Da′anzhai section are shell-based residual shell limestone，rose quartz -coarse-grained shell
limestone，bright crystal medium debris and muddy shell limestone；with calcite as the main mineral ingredients；the sedimentary
environment is mainly debris beach microfacies；the main reservoir space for dissolution infiltration holes，intergranular
holes and cracks with micro pores and micro throat；pore structure is mainly micro pore with micro throat and fine throat；
reservoir porosity concentrated between 0.5% to 2.0% and permeability are more concentrated between 0.001 to 1.000 mD.
The analysisled to the conclusion that sedimentary microfacies control the reservoir distribution；debris beach reservoir is the
most favorable facies；sedimentary palaeogeomorphology highland controlled the quality reservoir development；dissolution
and tectonic disruption played a constructive role in dissolution holes and cracks；compaction pressure solution and calcite
cementation had devastating effects on reservoir properties.

The Development Mechanism of Mesozoic Volcanic Reservoirs#br# in Guxi Area

GUO Feng*, CUI Dian

2016, 38(2):  39-48.  DOI: 10.11885/j.issn.1674-5086.2015.08.28.03

Asbtract ( 270 )   HTML   PDF (824KB) ( 710 )  

References | Related Articles | Metrics

The Mesozoic volcanic reservoirs are discovered in Gunan 2 Block and Ken 93 Block in Guxi area，which indicates
the huge potential for exploration of the Mesozoic volcanic rocks in this area. Given that the physical properties of Mesozoic
volcanic reservoirs vary fast in vertical and horizontal direction，we clarified the physical characteristics of different lithology
by observing under microscope 200 slices from 28 wells and did statistical analysis of 87 reservoir property samples，and found
out that the reservoir is with middle to low porosity，and low to extra low permeability on the whole. The evolution process of
reservoir pore and the law of physical characteristics change are also summarized. The controlling factors of reservoirs，such
as condensation-consolidation，hydrothermal filling，structural effect/ weathering，burial and dissolution，are clarified. Finally，
the development model of volcanic reservoirs under the control of lithology，unconformity and fractures are established，
combined with the analysis of oil and gas migration process，and the special model of volcanic reservoirs is set up in this region.

Cenozoic Fault Structure and Hydrocarbon Accumulation#br# Model in the Banqiao Sag

SONG Fan1*, SU Ni′na1, YAO Ruixiang2, CHU Shumin2, ZHANG Ruixue1

2016, 38(2):  49-58.  DOI: 10.11885/j.issn.1674-5086.2014.05.13.01

Asbtract ( 283 )   HTML   PDF (1390KB) ( 702 )  

References | Related Articles | Metrics

In order to reveal the relationship between the Cenozoic fault structure and hydrocarbon accumulation of Banqiao
sag，the fault activity and their reservoir-controlling mechanism are systematically researched using the oilfield structural analysis
method. The results show that the sag can be divided into three structural zones：the faulted tectonic transfer belt in the
north，the faulted nose belt in the central and strike-slip deformation belt in the south. The master faults exhibiting geological
periods vertically and segments horizontally，generate a lot of secondary faults. The fault activities at all levels formed the
panorama of Cenozoic fault structure. Based on comprehensive research of fault activity and carrier systems，as well as the
hydrocarbon distribution，two different models of migration and accumulation are established，which are“deep and shallow
accumulation in contemporaneous faults”and“shallow accumulation in secondary faults”respectively.

Prediction about the Abundant Belts of Tight Sandstone Gas#br# Reservoirs Through Gradual Penetration

PU Yong1，2*

2016, 38(2):  59-67.  DOI: 10.11885/j.issn.1674-5086.2015.01.15.11

Asbtract ( 266 )   HTML   PDF (757KB) ( 743 )  

References | Related Articles | Metrics

The sand gas reservoir of the upper sub-member of segment Xu4 in the western Yuanba region is characteristic of deep
burial，and the reservoir rock is mainly compose of grey and light-grey calcarenaceous sandy conglomerate and calcare-naceous
sandstone. Generally the reservoir is dense and thin，and of low porosity and low permeability fracture-pore. The testing results
of many wells show that calcarenaceous sandy conglomerate and calcarenaceous sandstone distribution with certain thickness
and pore development and fracture development control the abundant belts of natural gas. Considering the characteristics of
gas reservoir in the upper sub-member of segment Xu4，the characteristics of rock physical response of calcarenaceous sandy
conglomerate，and according to the gradual penetration principle，we made statistical probability prediction about the lithologic
using pre-stack elastic inversion on the basis of pre-stack simultaneous inversion，and obtained the beneficial lithologic distribution
area. By using physical parameter prediction method，we obtained effective thickness and distribution of the reservoir
in the beneficial lithologic distribution area on the basis of frequency division data volume. On the basis of pre-stack seismic
fracture density prediction and petrophysical parameters，made prediction about the abundant belts of natural gas of the upper
sub-member of segment Xu4.

Sandbody Accumulation Pattern and Key Controlling Factors of#br# Deep-water Deposits in Northwest Australian Shelf

YANG Fan1*, YU Xinghe2, LI Shengli2, LU Linlin3, CHEN Yuan3

2016, 38(2):  68-78.  DOI: 10.11885/j.issn.1674-5086.2014.07.28.03

Asbtract ( 236 )   HTML   PDF (2337KB) ( 680 )  

References | Related Articles | Metrics

The northwest Australian shelf is the hot spot of global deep water hydrocarbon exploration. The Vulcan subbasin
Vulcan Formation in western shelf deep water of northwest Australia is taken as an example and such questions are considered
as sand body forming type，deposition distribution and unclear controlling factor of sand rich area. Through well core
description，drilling and logging data analysis and seismic interpretation，slump deposits in front of marine delta model is built
to mainly study. It is found that the gentle slope in the southeast part of research area generates marine delta，and slump and
turbidite are developed under the boundary fault downthrown of Swan Graben. The steep slope in northwestern area developed
into subaqueous fan because of the direct sediments injection into the sea. Then the main controlling factors of deep water
deposits are studied. It is believed that“four stages and five elements”model controlled the sandbody distribution in the Vulcan
Sub-basin. Namely，structure style determines types of sediments；sea level changes constrain the accumulation of sandbody
among sequence layers；deposit bedform forms appearance shape of sediment system；accommodation zone changes distribution
pattern of the sediments，and deepwater bottom current re-transportates sandbody. The discovery is important for finding
reservoir and exploring oil gas in research area.

A Study on Pulsed-neutron Porosity Logging Response Difference in#br# Logging-while-drilling and Wireline

YUAN Chao1*, LIU Hanlin2, ZHANG Feng3, YUAN Yue4, LIU Juntao3

2016, 38(2):  79-85.  DOI: 10.11885/j.issn.1674-5086.2014.01.13.08

Asbtract ( 299 )   HTML   PDF (502KB) ( 552 )  

References | Related Articles | Metrics

Because the formation model and measurement condition are different，the pulsed-neutron porosity logging responseof
logging-while-drilling（LWD）is different from that of wireline（WL），so the study on the response difference can
provide theoretical basis for the logging interpretation of pulsed-neutron porosity logging while drilling. In this paper，Monte
Carlo method is employed to build different models to study the response differences under different logging environments.
The results show that the counting ratio under LWD conditions increases in three-order polynomial form with the increase of
porosity，and the WL neutron logging response displays the same changing trend，but there is a crossing point in the LWD and
WL logging response curves. The relative sensitivity to porosity in LWD is greater than that in WL，but the drilling collar in
LWD tool can reduce the counting statistics of thermal neutron，which may influence the measurement accuracy. The effect
of different logging environments on the logging response of LWD and WL decreases with the increaseof porosity. The effect
of lithology，shale content and borehole size on the logging response difference of LWD is larger than that of WL. When the
borehole is filled with fresh water，oil and brine，the effect on logging response is slight and can be ignored. While the borehole
is full of gas，the effect on logging response of LWD is smaller than WL.

The Trilinear Seepage Model for Fractured Horizontal Well in Shale#br# Gas Reservoir

GUO Xiaozhe1*, ZHOU Changsha2

2016, 38(2):  86-94.  DOI: 10.11885/j.issn.1674-5086.2013.10.16.04

Asbtract ( 234 )   HTML   PDF (522KB) ( 783 )  

References | Related Articles | Metrics

Shale gas reservoirs with plenty of natural fractures and nano-scale poreshave a variety of seepage patterns，fractured
horizontal well has become the key production method，in which establishment and solution of percolation mathematical model
is of a strong theoretical and practical value. Drawing lessons from the existing three linear seepage model，we re-designed
the composition of the model，and established seepage mathematical model including adsorption and desorption. The capacity
formula of single well production of fracturing shale gas reservoir horizontal well and the bottom hole pressure formula are
deduced with the help of dimensionless and Laplace transform. Then we applied the results to the analysis of the influence
factors in the process of single well production. The results show thatthe formulae obtained by the simplified model can calculate
and predict the changes of shale gas production with convenience and accuracy，and also provide the optimization of design
parameters for fracturing design.

Trilinear-flow Model of Fractured Well on Asymmetric Regions for#br# Low-Permeability Reservoir

JIA Yonglu1, DENG Qi1*, NIE Renshi1, CAI Mingjin2, WANG Yicheng3

2016, 38(2):  95-102.  DOI: 10.11885/j.issn.1674-5086.2013.06.14.02

Asbtract ( 222 )   HTML   PDF (577KB) ( 653 )  

References | Related Articles | Metrics

A trilinear-flow model of fractured well on asymmetric regions for low-permeability reservoir is established. Different
fromthe traditional model，the new model takes into account more complex conditions：the impact of threshold pressure
gradient and multiple asymmetric boundaries. The model is solved using Laplace transformation，and the bottom pressure in
the Laplace space is obtained. Type curves of well test are programmed and plotted by the numerical conversion. The type
curves of the new model are obviously different from the traditional one. The differences are as follows：the curves of dimensionless
pressure and pressure derivation climb up at the later stage because of the threshold pressure gradient，and the greater
the threshold gradient is the earlier and higher the curves climb up；the number of boundaries on asymmetric regions and the
relative positions（vertical or parallel）of fracturing fractures and boundaries have a remarkable influence on the typical curves
with low-permeability wells with vertical fractures. The more boundaries there are，the higher the curves climb up，and under
the same circumstances（with the same boundary types and the same dimensionless boundary distance），significant differences
exist on the curves of boundary response different relative position（vertical or parallel）

Study on Layer Combination Optimization Method of Subdivision Water#br# Injection in High Water-cut Reservoirs

FENG Qihong1, WANG Bo2*, WANG Xiang1, YANG Yahui1, HAN Xiaodong3

2016, 38(2):  103-108.  DOI: 10.11885/j.issn.1674-5086.2013.12.17.04

Asbtract ( 194 )   HTML   PDF (400KB) ( 548 )  

References | Related Articles | Metrics

In the high water cut period，even after subdivision of reservoir layers，serious problems still remain，such as interlayer
conflict and inconsistency and invalid water cycle. to solve them，subdivision water injection is an effective approach of
improving the development effect and water-flooding sweeping efficiency. The key to success of subdivision water injection is
to determine the reasonable combination of layers according to the reservoir properties and development situations of each layer.
This article adopts optimal segmentation methods，considering the Fisher principle with expertise and the various indicators
reflecting development effect. In addition，it introduces the concept of interval diameter considering the various factors to
determine the optimal scheme for layer division，which can reflect the contradiction between layers，such as permeability，
producing degree，absorption strength，restraining barrier and so on. The comparison of instance analysis with the results of
reservoir simulation shows that this method is simple but reliable and can help adjust the subdivision water injection at high
water cut stage.

A Study on Evaluation of Reservoir Quality of Fracturing Wells

FENG Wenyan1, ZENG Fanhui2*, GUO Jianchun2, YIN Congbin2, HAN Xiaoyu3

2016, 38(2):  109-114.  DOI: 10.11885/j.issn.1674-5086.2013.01.23.02

Asbtract ( 218 )   HTML   PDF (365KB) ( 701 )  

References | Related Articles | Metrics

Accurate evaluation and understanding of well quality before fracturing can improve production and profit significantly.
This paper firstly divides the reservoir capacity into reservoir quality and flow capacity which fall further into elements
as porosity，permeability，gas saturation and other accessible and quantifiable indicating parameters. We establish a multi-level
quality evaluation index system of fracturing wells，which combines fuzzy comprehensive evaluation method with grey correlation
analysis theory，and presents a comprehensive evaluation method through multi-level fuzzy and grey correlation analysis.
After multi-factor comprehensive evaluation，this paper gets a comprehensive evaluation index，which is used to evaluate the
reservoir quality. Field application shows that the method is highly credible and accurate，and can quickly evaluate the quality
of fracturing wells.

A Study of Stress Sensitivity of Abnormal High Pressure Shale Gas#br# Reservoir and Reasonable Productivity Allocation

YANG Bo1*, LUO Di2, ZHANG Xin1, WU Dong2, SHANG Shaofen2

2016, 38(2):  115-121.  DOI: 10.11885/j.issn.1674-5086.2014.03.11.01

Asbtract ( 314 )   HTML   PDF (578KB) ( 697 )  

References | Related Articles | Metrics

Production of abnormal high pressure shale gas reservoir is characteristic of rapid decline of initial production. On the
one hand，this is related to the well production by fracturing of low permeability shale gas；on the other hand，it may be related
to the pressure-dependent permeability of reservoir and fracture. This paper analyzes the stress- sensitivity of hydraulic fracture
and shale gas reservoir，and find out that there is a big difference in the mechanical properties between them，so they should be
taken into account separately. By using numerical simulation method，we calculate the effect of pressure-dependent permeability
and production allocationon the estimated ultimate recovery（E UR），and the results show that the effect of stress sensitivity on
shale gas reservoir is little，while the influence of hydraulic fracture stress sensitivity is stronger. If stress sensitive permeability
is only related to pressure，the production allocation has very little influence on EUR. But if under the high production rate and
with stronger permeability stress sensitivity decay curve，the initial production proration has a greater influence on EUR. With
graphics diagnosis method，we confirmed that gas wells with lower initial allocation are of greater production potential. The
research results can be used for reasonable proration optimization of high pressure shale gas wells.

Prediction of the Drainage Volume of Shale Gas Reservoir with Fast#br# Marching Method

TENG Bailu*, CHENG Linsong, HUANG Shijun, JIA Zhen, AI Shuang

2016, 38(2):  122-128.  DOI: 10.11885/j.issn.1674-5086.2013.10.21.01

Asbtract ( 224 )   HTML   PDF (588KB) ( 811 )  

References | Related Articles | Metrics

The development of unconventional energy，especially shale gas reservoir，is getting more and more attention；
however，prediction of the drainage volume of shale gas reservoir is to be improved. Fast marching method is a fast and
efficient method to present the front of the pressure. Taking into account desorption and slippage，the flow regions can be
divided with the compound linear flow model by Van Kruysdijk. The Eikonal equation of the matrix and the fracture can be
obtained and solved with fast marching method，then drainage volume of the reservoir at different time can be obtained，and
the comparison of the condition whether or not considering desorption and the effect of slippage can be seen easily. The result
shows that slippage accelerates the increase of drainage volume and desorption slows the increase of drainage volume. The
influence of slippage is greater than desorption.

Oil-based Drilling Fluid Technology of Nadu Formation in Baise Oilfield

ZHOU Chenghua1*, ZHANG Zhen1, HU Deyun1, YANG Guoxing1, DENG Yuanzhou2

2016, 38(2):  129-135.  DOI: 10.11885/j.issn.1674-5086.2014.03.05.07

Asbtract ( 252 )   HTML   PDF (416KB) ( 693 )  

References | Related Articles | Metrics

The Nadu formation of Baise Oilfield is fairly complex，in which malignant collapse caused by borehole instability
happen easily during drilling. To solve this problem，the strong sealing and inhibitive oil-based drilling fluid is researched and
developed. This system comprises of nanoscale solid-liquid sealing material so as to improve the sealing properties and has
good anti-pollution，lubricating and rheological properties. The experiment applied in third section of well Kun 8 6HF shows
that the oil-based drilling fluid can prevent the wellbore from collapsing and meet the requirement of safe drilling. Thus it has
efficiently solved the complex problem of malignant collapse during horizontal well drilling in Nadu formation.

Seepage Flow and Well Test Model for Viscous-Elastic Polymer#br# Flooding Reservoir

LIANG Guangyao1*, SHEN Pingping1, LIAO Xinwei2, LIU Shangqi1, CHEN Heping1

2016, 38(2):  136-142.  DOI: 10.11885/j.issn.1674-5086.2014.02.23.02

Asbtract ( 304 )   HTML   PDF (646KB) ( 570 )  

References | Related Articles | Metrics

The rheological behaviors of high molecular polyacrylamide（HPAM）solution in porous media and rheometer were
measured in experiments，which demonstrated the existence of viscoelasticity in polymer flooding process，and it complied with
non-Newtonian power-law seepage pattern within the scope of medium shear rate（0.1～100.0 s−1）. Based on the established
viscous-elastic constitutive equation related to varying cross-section throat model，effective viscosity of polymer solution was
expressed as the sum of shear viscosity and elastic viscosity，the mathematical model for transient flow in viscous-elastic polymer
flooding reservoir was established and solved by finite difference method to acquire numerical solution，then dimensionless
well test curves were developed. The effect of viscoelasticity on the shape of well test curves for viscous-elastic polymer flooding
reservoir was then discussed，by comparing theoretical with realistic well test curves. The results show that the existence
of elasticity causes significant rise of formation pressure near polymer-injection well，but hardly changes the shape of well test
curves. Therefore，it is feasible to ignore the effect of elasticity and acquire parameters by adopting well test models based on
non-Newtonian power-law flow for viscous-elastic polymer flooding reservoir.

An Experimental Study on Factors Affecting the Effect of Calcium#br# Carbonate Scale Inhibition

LI Hongjian1*, SUN Jianbo1, MENG Xue2, TANG Xin3, WANG Deyu3

2016, 38(2):  143-148.  DOI: 10.11885/j.issn.1674-5086.2014.06.29.02

Asbtract ( 239 )   HTML   PDF (447KB) ( 692 )  

References | Related Articles | Metrics

In order to study the influence of the combined action of multiple factors on the calcium carbonate scale inhibition，
100 mg/L of PESA screened out by static scale inhibition method were employed in the experimental research on the
factors affecting calcium carbonate scale inhibition. First，we studied the impact of inhibitor type，inhibitor concentration，
supersaturation，salinity，and pH on calcium carbonate scaling inhibition separately by single factor analysis. Then orthogonal
experiment was designed based on the experimental results of different factors. The experiment studied the combined action of
temperature，salinity，partial pressure of CO2 and pH. The result of the single factor analysis showed that the scale inhibition
rate of PESA decreased as supersaturation increased，and climbed up first and then declined slowly as salinity or pH increased.
Scale inhibition rate reached 95.85% at the critical salinity，which turned to be 50 g/L. And optimal inhibition rate was 90%
when pH varied from 6.5 to 8.0. The result of the orthogonal experiment showed that temperature was the key factor on scale
inhibition rate with 8.2 Xbar-R and 0.002 P. Followed by pH and CO2 partial pressure，the influence of salt content was negligible.
Finally，the optimum combination of influencing factors was obtained，and the analysis showed that 60 ℃，7.5 pH，
1.5 MPa CO2 partial pressure，5.5 g/L salinity would produce the best scaling inhibition result.

Study and Application of Movable Gel for High-Temperature and#br# High-Salt Gasikule Reservoirs

LUO Yun1*, LUO Wenli2, WANG Qiang2, LIU Rui1

2016, 38(2):  149-154.  DOI: 10.11885/j.issn.1674-5086.2014.08.21.03

Asbtract ( 232 )   HTML   PDF (609KB) ( 572 )  

References | Related Articles | Metrics

Abstract：A novel movable gel for high-temperature and high-salt reservoirs is proposed in this paper. The movable gel consists
of the star-polymer（CA 2588）with temperature-resistance and salt-resistance and organic crosslinking agent（HT 2008）.
Systemic investigation was carried out to examine the influence of star-polymer molecular weight，star-polymer concentration，
crosslinker dosage，and pH value on gel viscosity and gelation time. It was observed clearly by the environmental scanning
electron microscope that the interpenetrating polymer network structure was formed within the movable gel. The viscosity of
the movable gel（0.2% CA 2588+0.66% HT 2008）reached the peak value of 43 900 mPa·s in brine salinity of 117 000 mg/L
at 126 ℃. In addition，no obvious decrease in the viscosity of movable gel was found after 180 days. The movable gel with
star-polymer（CA 2588）and organic crosslinking agent（HT 2008）was used for deep profile control and gel-flooding in
Gasikule E13reservoirs，and achieved the desired effect.

The Effect of Sustained Casing Pressure on the Mechanical Integrity of#br# Cement Sheath in Gas Wells

ZHANG Zhi1*, XU Honglin2, LIU Zhiwei1, LI Wei3, SHI Taihe1

2016, 38(2):  155-161.  DOI: 10.11885/j.issn.1674-5086.2014.02.13.01

Asbtract ( 279 )   HTML   PDF (1063KB) ( 755 )  

References | Related Articles | Metrics

Sustained casing pressure（SCP），resulted from downhole operations，the leakage of casing and oil tube or packer
poses great challenges to the sealing integrity of cement sheath in HTHP gas wells. Thus，we estasblished the failure calculation
model and the stresses of cement sheath，and studied the influences of SCP on the stresses and failure of cement sheath，based on
the multi-layer thick wall cylinder theory of elastic mechanics and Mohr-Coulomb failure criterion. Results show that the SCP
problem will make cement sheath sustain overlarge tangential tensile stress which is the principal factor for its failure. Besides，
the tangential tensile stress that is resulted from the increasing temperature in wellbore will increase the risk of the failure of
cement sheath. The larger the SCP value，the lower the safety factor of cement sheath，and the influence of temperature effect on
the safety factor is not clear. For high temperature and high pressure gas wells，a safety factor diagram of cement sheath can be
drawn according to parameters of well construction（formation-cement sheath-casing），which gives the basis for determining
proper allowable maximum SCP value and is of great guiding significance to increase the wellbore safety and to extend the
working life of gas well production.

Acoustic Communications Over Downhole Drill Strings Using#br# Adaptive BPSK

ZHOU Jing*, TIAN Huan, GAO Jianbang, QIU Bin

2016, 38(2):  162-168.  DOI: 10.11885/j.issn.1674-5086.2013.12.25.02

Asbtract ( 274 )   HTML   PDF (450KB) ( 834 )  

References | Related Articles | Metrics

Using acoustic waves to transmit downhole information through the drill-string transmission channel is a promising
approach that meets the requirements for the highspeed and large-volume data transmission in modern drilling. In the studies
about acoustic signal transmission channel characteristics and acoustic communication，we developed a mathematical channel
model for the description of a guided acoustic wave based on waveguide theory. To overcome the phase shift during transmission，
we applied BPSKand adaptive spread-spectrum communication system to detecting the phase shift of carrier，which
ensures correct data transmission. Field application shows that this method can realized high speed data transmissionwith high
reliability and low error rate. In this way，much higher data rates can be realized in future deep drilling applications. Drill string
acoustic telemetry is an effective transmission method to retrieve downhole data in drilling applications.

Early Intelligent Kick Warning in Well Drilling Based on Fuzzy#br# Expert System

ZHANG He1*, LI Qiying1, ZHANG Luzhi2, MI Ling1

2016, 38(2):  169-175.  DOI: 10.11885/j.issn.1674-5086.2013.12.04.05

Asbtract ( 267 )   HTML   PDF (520KB) ( 891 )  

References | Related Articles | Metrics

In well drilling process，it is difficult to establish the intelligent early kick warning model based on sample information
due to the complexity of geological information or the lack of adjacent well data. Through researches on the mechanism
and characteristics of the kick occuring，we suggest an exploratory well drilling intelligent early kick warning method by using
drilling expert knowledge and hierarchical fuzzy expert system and develop corresponding software system. By fuzzifying
parameters of kick occurring and with calculation based on fuzzy inference rule，this model is able to provide fast andaccurate
early kick warning. Field test data reveals thatthe intelligent early kick warning results are good and have a good application
prospect.

A Study on the Casing Wear Mechanism in Highly-deviated Well Drilling

LIAN Zhanghua1*, YU Hao1, LIU Yonghui2, LIN Tiejun1, ZHANG Qiang1

2016, 38(2):  176-182.  DOI: 10.11885/j.issn.1674-5086.2014.05.08.02

Asbtract ( 314 )   HTML   PDF (813KB) ( 656 )  

References | Related Articles | Metrics

Aimed at studying the wear failure in the drilling process of highly-deviated well，this paper firstly carried out casing
wear experiment research. According to the liner casing wear model based on the energy loss suggested by Dawson R and
White J，and the experiment，the joint-casing wear coefficient is obtained. The finite element model of casing wear mechanism
research is constructed using ABAQUS software. This paper uses the re-development user subroutine and Arbitrary Lagrange-
Euler mesh. In the process of numerical simulation，the location of the wear node can be adjusted timely，the mesh element
is smoothed，and the contact relations between joint and casing is altered continuously，which all contribute to the study on
casing wear mechanism. Based on the shape of worn casing，the numerical simulation research is carried out to determine the
remaining collapse strength，as a result of which，the relationship between the maximum wear depth and wear time is obtained.
On this basis，the exact relationship between the maximum wear depth and wear time is determined to predict the maximum
wear depth and remaining strength of casing after a period of accumulating wear time，which also provides theoretical basis for
the safety assessment of worn casing.