- Article List
- Full Abstracts
-
New progress and enlightenment of oil and gas exploration and geological understanding in Qaidam Basin
LI Guoxin, SHI Yajun, ZHANG Yongshu, CHEN Yan, ZHANG Guoqing, LEI Tao
2022, Vol.34(6): 1–18
Abstract
(
454 )
HTML
(0 KB)
PDFEN
(13716 KB)
(
418
)
-
Sedimentary characteristics of Cambrian Canglangpu Formation in central Sichuan Basin
WANG Liang, SU Shute, MA Zike, PU Jing, YAO Linfang, LIU Yu, LUO Yang
2022, Vol.34(6): 19–31
Abstract
(
316 )
HTML
(0 KB)
PDFEN
(12625 KB)
(
287
)
-
Sequence stratigraphic characteristics and favorable reservoirs distribution of Permian Qixia Stage in Weiyuan-Gaoshiti area， Sichuan Basin
LI Ling, ZHANG Zhaokun, LI Minglong, NI Jia, GENG Chao, TANG Sizhe, YANG Wenjie, TAN Xiucheng
2022, Vol.34(6): 32–46
Abstract
(
324 )
HTML
(0 KB)
PDFEN
(18165 KB)
(
243
)
-
Pore structure characteristics and genetic mechanism of Triassic Chang 7 shale oil reservoir in Longdong area
WEN Zhigang, LUO Yushu, LIU Jiangyan, ZHAO Chunyu, LI Shixiang, TIAN Weichao, FAN Yunpeng, GAO Heting
2022, Vol.34(6): 47–59
Abstract
(
289 )
HTML
(0 KB)
PDFEN
(9918 KB)
(
274
)
-
Fracture development models and significance of Ordovician WufengSilurian Longmaxi shale in Luzhou area，southern Sichuan Basin
YAN Jianping, LUO Jingchao, SHI Xuewen, ZHONG Guanghai, ZHENG Majia, HUANG Yi, TANG Hongming, HU Qinhong
2022, Vol.34(6): 60–71
Abstract
(
377 )
HTML
(0 KB)
PDFEN
(11112 KB)
(
262
)
-
Tectonic characteristics and favorable exploration zones of Paleozoic in Dongpu Sag
YU Haibo
2022, Vol.34(6): 72–79
Abstract
(
314 )
HTML
(0 KB)
PDFEN
(5971 KB)
(
300
)
-
Sequence stratigraphic framework and platform margin belt distribution of Cambrian in northern Tarim Basin
LIU Yongli, LI Guorong, HE Zhao, TIAN Jiaqi, LI Xiaoxiao
2022, Vol.34(6): 80–91
Abstract
(
263 )
HTML
(0 KB)
PDFEN
(9658 KB)
(
188
)
-
Geochemical characteristics and hydrocarbon generation potential of Upper Paleozoic source rocks in Ganquan area，Ordos Basin
WEI Xin, TANG Jianyun, SONG Hongxia, CHEN Yubao
2022, Vol.34(6): 92–100
Abstract
(
270 )
HTML
(0 KB)
PDFEN
(4009 KB)
(
254
)
-
Characteristics and main controlling factors of tight sandstone reservoirs of Permian Shan 2 to He 8 members in southeastern Ordos Basin
MI Weiwei, XIE Xiaofei, CAO Hongxia, MA Qiang, DU Yonghui, ZHANG Qiong, DENG Changsheng, SONG Jiaxuan
2022, Vol.34(6): 101–117
Abstract
(
276 )
HTML
(0 KB)
PDFEN
(15081 KB)
(
311
)
-
Lithology prediction technology and its application of Paleogene Wenchang Formation in Panyu 4 depression，Pearl River Mouth Basin
ZHANG Weiwei, LIU Jun, LIU Lihui, ZHANG Xiaozhao, BAI Haijun, YANG Dengfeng
2022, Vol.34(6): 118–125
Abstract
(
219 )
HTML
(0 KB)
PDFEN
(4962 KB)
(
170
)
-
Reservoir characteristics of the fourth member of Sinian Dengying Formation and its implications for oil and gas exploration in Moxi area，Sichuan Basin
GENG Xiatong, XING Fengcun, YAN Haijun, FU Hui, CHAI Hanbing, LIU Zhibo, CHEN Xiaoquan, GU Qiang
2022, Vol.34(6): 126–140
Abstract
(
286 )
HTML
(0 KB)
PDFEN
(16196 KB)
(
275
)
-
Composite sand body architecture and controlling factors of the lower Minghuazhen Formation of Neogene in northern Qinhuangdao 32-6 oilfield
REN Mengyi, HU Guangyi, FAN Tingen, FAN Hongjun
2022, Vol.34(6): 141–151
Abstract
(
260 )
HTML
(0 KB)
PDFEN
(7007 KB)
(
206
)
-
Formation mechanism and percolation characteristics of secondary foamy oil by gas injection in super heavy oil
LU Yingbo
2022, Vol.34(6): 152–159
Abstract
(
235 )
HTML
(0 KB)
PDFEN
(3791 KB)
(
209
)
-
Profile change rule during Cr3+ polymer weak gel flooding and related improving method
XIE Kun, SU Cheng, LIU Changlong, MEI Jie, YU Haitao, HE Xin, LU Xiangguo
2022, Vol.34(6): 160–170
Abstract
(
187 )
HTML
(0 KB)
PDFEN
(4754 KB)
(
179
)
-
New progress and enlightenment of oil and gas exploration and geological understanding in Qaidam Basin
LI Guoxin, SHI Yajun, ZHANG Yongshu, CHEN Yan, ZHANG Guoqing, LEI Tao
2022, Vol.34(6): 1–18
Abstract
(
454 )
PDF (13716 KB) (
418
)
doi: https://doi.org/10.12108/yxyqc.20220601
After the arduous struggle of several generations， the only oil and gas production base in Tibet Plateau has been built in Qaidam Basin， which has become a ballast for the economic and social development of GansuQinghai-Tibet region. By systematically summarizing the oil and gas exploration progress and exploration results in Qaidam Basin in recent years，the laws of basin formation， hydrocarbon generation， reservoir formation and reservoir accumulation were summarized， and the important fields and directions of exploration transformation in the future were pointed out. The research results show that：（1）Since the establishment of major science and technology projects in 2007，especially since the 12th Five-Year Plan， large oil and gas fields with 100 million ton reserves have been discovered by relying on scientific and technological innovation in Kunbei fault terrace， Yingxiongling structure，Altun Piedmont and Zahaquan Sag， meanwhile，original theories that are rare in other basins about hydrocarbon generation，reservoir formation and hydrocarbon accumulation mechanism were formed.（2）By systematically summarizing the exploration discovery and important geological cognition since the 12th Five-Year Plan，four major changes in future oil and gas exploration were proposed：from shallow to deepshallow combination， from structure to structure-lithology combination， from clastic rocks to multi-lithology combination，and from conventional to conventional and unconventional combination. Four major future fields were determined，including Paleogene-Neogene shale oil in western Qaidam Basin，Quaternary mudstone biogas of eastern Qaidam Basin，deep strata in northern margin of Qaidam Basin and Paleogene multi-lithology in western Qaidam Basin.（3）These research results will promote the transformation and deve-lopment of oil and gas exploration in Qaidam Basin and the development of oil and gas geology theory and technology in strongly reformed basins， and provide important support for the continuous exploration discovery of oil and gas reservoirs in various types of petroleum systems.
-
Sedimentary characteristics of Cambrian Canglangpu Formation in central Sichuan Basin
WANG Liang, SU Shute, MA Zike, PU Jing, YAO Linfang, LIU Yu, LUO Yang
2022, Vol.34(6): 19–31
Abstract
(
316 )
PDF (12625 KB) (
287
)
doi: https://doi.org/10.12108/yxyqc.20220602
Based on the regional structural characteristics，field outcrops，drilling and logging data，the sedimentary characteristics of Cambrian Canglangpu Formation in central Sichuan Basin were studied，the paleosedimentary environment was reconstructed，the lateral distribution characteristics of each sedimentary facies were defined， and the favorable reservoir development areas were predicted. The results show that：（1）Deep-water shelf facies are developed in Deyang-Anyue rift trough in central Sichuan Basin，mainly composed of clastic rocks. Shallowwater shelf facies are developed in the areas of Gaomo-Longnusi-north slope to the east of the rift trough，which can be divided into three sedimentary sub-facies. The lithologies of carbonate shallow-water shelf facies are mainly finely crystalline limestone and finely crystalline dolomite， followed by grainstone and granular dolomite. Archaeocyatha and brachiopods can be observed，and the gamma and resistivity logs are in a box shape. The lithologies of debris shallow-water shelf facies are mainly siltstone or sandy mudstone with the gamma and resistivity logs bell or funnel-shaped. The mixed shallow-water shelf is interbedded with sandy dolomite，sandy limestone and mudstone with the gamma and resistivity logs toothed.（2）The sedimentary palaeogeomorphology pattern of Canglangpu Formation is high in the west and low in the east. The water body gradually deepened from west to east，and the stratum thickness gradually increased. The lower sub-member of the first member of Canglangpu Formation in Gaomo-Longnvsi-north slope area is mainly mixed shallow-water shelf facies，the upper sub-member of the first member of Canglangpu Formation is mainly carbonate shallow-water shelf facies， and the second member of Canglangpu Formation is mainly debris shallow-water shelf facies.（3）The sedimentary facies of Canglangpu Formation in the study area control the development of high-quality reservoirs. The reservoir mainly develops in the carbonate shallow-water shelf of the upper sub-member of the first member of Canglangpu Formation. The granular shoal is the most favorable sedimentary microfacies，among which dolomite reservoir is the best， followed by limestone. On the plane, high-quality reservoirs mainly develop along the high part of the structure at the edge of Deyang-Anyue rift trough， showing a banded distribution.
-
Sequence stratigraphic characteristics and favorable reservoirs distribution of Permian Qixia Stage in Weiyuan-Gaoshiti area， Sichuan Basin
LI Ling, ZHANG Zhaokun, LI Minglong, NI Jia, GENG Chao, TANG Sizhe, YANG Wenjie, TAN Xiucheng
2022, Vol.34(6): 32–46
Abstract
(
324 )
PDF (18165 KB) (
243
)
doi: https://doi.org/10.12108/yxyqc.20220603
Based on cores，cuttings and logging data，the sequence stratigraphic characteristics of Permian Qixia Stage in Weiyuan-Gaoshiti area of Sichuan Basin were comprehensively analyzed， and favorable reservoir distribution and controlling factors were pointed out. The results show that： （1）Two type Ⅰ sequence boundaries （bottom boundary of Liangshan Formation and top boundary of Qixia Formation）and two type Ⅱ sequence boundaries（top boundary of Qi 1 member and top boundary of Qi 2b member）were identified in Permian Qixia Stage in Weiyuan-Gaoshiti area. Accordingly， the Qixia Stage was divided into SQ1， SQ2 and SQ3，corresponding to Liangshan Formation and Qi 1 member，Qi 2b member and Qi 2a member，respectively.（2）The sequence filling framework and sequence plane distribution characteristics of Qixia Stage show that the bottom stratum （SQ1）has the characteristics of onlapping to the pre-depositional palaeogeomorphology highland， and the middle and upper strata（SQ2 and SQ3）continuously migrate from the sedimentary geomorphic highland to the lowland， showing the sequence filling pattern of onlapping at the bottom and migration at the middle-upper.（3）During the sedimentary period of SQ2 and SQ3 highstand systems tracts in the study area，mound-shoal complexes with large thickness and good lateral continuity were developed in the paleogeomorphology highlands and slope breaks， which laid material foundation for reservoir development. During that period，the sea level was in high-frequency change. The mound-shoal complexes high-frequency exposure karstification，improving the reservoir properties， and the pressure-soluble skeleton formed after the early dolomitization， which is beneficial to the development of the reservoir.（4）The development and distribution of thin dolomite reservoirs are controlled by sedimentary facies and karstification. The highlands and slope breaks in Qixia Stage are potential areas for next exploration.
-
Pore structure characteristics and genetic mechanism of Triassic Chang 7 shale oil reservoir in Longdong area
WEN Zhigang, LUO Yushu, LIU Jiangyan, ZHAO Chunyu, LI Shixiang, TIAN Weichao, FAN Yunpeng, GAO Heting
2022, Vol.34(6): 47–59
Abstract
(
289 )
PDF (9918 KB) (
274
)
doi: https://doi.org/10.12108/yxyqc.20220604
The pore structure characteristics of Chang 7 shale oil reservoir were characterized by high pressure mercury injection（HPMI）， low-temperature nitrogen adsorption（LTNA）， and nuclear magnetic resonance（NMR）， and the effects of dominant diagenesis on pore structure were discussed. The results show that： （1）The shale oil reservoir of Triassic Chang 7 member in Longdong area is mainly feldspathic lithic sandstone and lithic arkose， with an average porosity of 7.55% and an average permeability of 0.149 mD，belonging to typical ultra-low porosity and ultra-low permeability reservoir. The reservoir space types are mainly dissolved pores， residual intergranular pores and clay intercrystalline pores， and a small amount of micro fractures are developed.（2）The reservoir is characterized by high displacement pressure， ranging from 0.67 MPa to 27.54 MPa， with an average of 5.54 MPa low maximum mercury saturation， ranging from 33.22% to 84.35%， with an average of 64.71%， and small average throat radius， ranging from 0.008 μm to 0.163 μm， with an average of 0.277 μm.， showing strong heterogeneity. （3）The isotherms of the typical samples in the study area are all in an inverse S shape， belonging to a typical type Ⅳ isotherm. The type of hysteresis loop is dominated by type H3，indicating that the shape of pores less than 200 nm is mainly parallel plate shape.（4）The pore diameter of Chang 7 shale oil reservoir in the study area is mostly less than 30 μm. With the improvement of physical properties of samples，the proportion of larger pores （greater than 200 nm）in the reservoir increases gradually.（5）The shale oil reservoir of Chang 7 member in the study area has experienced three types of diagenesis： strong compaction， weak cementation and weak dissolution. Cementation and compaction have a negative effect，and dissolution has a constructive effect on the improvement of reservoir quality and pore structure.
-
Fracture development models and significance of Ordovician WufengSilurian Longmaxi shale in Luzhou area，southern Sichuan Basin
YAN Jianping, LUO Jingchao, SHI Xuewen, ZHONG Guanghai, ZHENG Majia, HUANG Yi, TANG Hongming, HU Qinhong
2022, Vol.34(6): 60–71
Abstract
(
377 )
PDF (11112 KB) (
262
)
doi: https://doi.org/10.12108/yxyqc.20220605
Based on the data of cores， electrical imaging logging and conventional logging，the fracture types and combination characteristics，fracture information extraction and fracture development models of the deep shale of Ordovician Wufeng Formation-Silurian Longmaxi Formation in Luzhou area of southern Sichuan Basin were studied on the electrical imaging logging images，and the acoustic logging response of different fracture development models and their impact on the later fracturing stimulation were analyzed. The results show that：（1）With the increase of formation depth，the fracture dip angle and the complexity of structural fracture types gradually decrease of Ordovician Wufeng-Silurian Longmaxi shale in Luzhou area，southern Sichuan Basin. The well target section near the strong tectonic activity zone shows obvious development of medium and high angle structural fractures.（2）According to the relationship between structural fractures and bedding development， the fracture development models in the study area can be divided into six types： mixed development of structural fractures and bedding， medium-density bedding，tight bedding， strong structural fractures and weak bedding，large-scale structural fractures， and dense type. Among them， the mixed development of structural fractures and bedding and the medium-density bedding are the preferred types of fracturing.（3）Curve L was introduced（σ = k/n， k is a constant， σ is the average opening， n is the number of bedding）， the range of k and n values can effectively characterize the relative development degree of structural fractures and bedding，so as to divide and identify different fracture development models in the coordinate system.（4）Different fracture development models have certain differences in the P-wave and S-wave time difference and rock mechanical properties. The P-wave time difference of the mixed development of structural fractures and bedding and the strong structural fracture and weak bedding is smaller than that of the medium-density bedding and the tight bedding. The shear strength of the medium-density bedding is lower than that of the tight bedding.
-
Tectonic characteristics and favorable exploration zones of Paleozoic in Dongpu Sag
YU Haibo
2022, Vol.34(6): 72–79
Abstract
(
314 )
PDF (5971 KB) (
300
)
doi: https://doi.org/10.12108/yxyqc.20220606
Based on seismic and drilling data， the structure of Dongpu Sag was analyzed， and the favorable exploration zones of Paleozoic were predicted by considering gas generation intensity in the high thermal evolution zones of coal measure source rocks. The results show that：（1）The Dongpu Sag has the evolution characteristics of IndosinianYanshanian compressional zone， Paleogene extensional zone，fault-sag controlled sub-sag in the sedimentary period of Es4-Es3，and strike-slip block in the sedimentary period of Es2，resulting in the structure of multiple faults，multiple protrusions and multiple sub-sags in the Paleogene.（2）The“checker-board”petroleum system was formed in Dongpu Sag under the superposition of multi-phase tectonic stress. The oil and gas in each petroleum system generally has the characteristics of“upper oil and lower gas， early oil and late gas， and continuous accumulation” . On the whole， four types of oil and gas reservoirs were developed， and the oil and gas enrichment model of “near source accumulation，continuous accumulation，and fault controlled enrichment”in weakly modified basins was established.（3）The central area of Dongpu Sag is characterized by weak structural transformation，oil and gas enrichment，and the distribution of Paleozoic residual strata is controlled by the NS compression fault，which is a favorable zone for deep coalbed methane primary reservoirs. In the high thermal evolution area with the source rock as the center， Weicheng-Wenliu structural belt can be selected as favorable exploration zones by using the superposition of multiple reservoiring factors.
-
Sequence stratigraphic framework and platform margin belt distribution of Cambrian in northern Tarim Basin
LIU Yongli, LI Guorong, HE Zhao, TIAN Jiaqi, LI Xiaoxiao
2022, Vol.34(6): 80–91
Abstract
(
263 )
PDF (9658 KB) (
188
)
doi: https://doi.org/10.12108/yxyqc.20220607
Based on the identification of key sequence boundaries，analysis of sequence duration，sedimentary facies division and analysis of stratigraphic superposition structure of Cambrian in northern Tarim Basin， the distribution of platform margin belt was sketched out with the third-order sequence as a unit， and its favorable exploration areas were defined. The results show that： （1）Ten third-order sequences were identified in the Cambrian strata in the northern Tarim Basin，and they were numbered from SQ1 to SQ10 from bottom to top. Gentle slope sediments are developed in the SQ1-SQ2 period of the Lower Cambrian， which are type Ⅰ sequences. In SQ3- SQ5 period，carbonate platforms of gentle slope are developed，which are type Ⅱ sequences. Carbonate platforms are developed in SQ6 period of Middle Cambrian，which are type Ⅱ sequences. Carbonate rimmed platforms are developed during SQ7- SQ10 period of Middle and Upper Cambrian. SQ 7 and SQ 9 are type Ⅰsequences，and SQ8 and SQ10 are type Ⅱ sequences.（2）The platform margin facies belt of SQ3 sequence in the study area shows wide spatial distribution. It is distributed along Keping uplift to Shaya uplift in near EW direction，and along Shaya uplift to Shuntuoguole uplift in near N-S direction. The platform margin facies belt of SQ4-SQ10 is distributed along N-S direction， showing good successive development characteristics， with the platform margin pushing towards the slope-basin area and displaying clear progradation pattern. High-energy reef shoal facies belt of SQ3-SQ10 is widely distributed， and the reef shoal facies reservoir area on the platform margin is large.（3）The platform margin facies belt in the study area extending in the N-S direction，located in the east of well TS2，is the most favorable zone for reservoir development. It is also the most favorable exploration area because of its good spatial relationship with Cambrian main source rocks.
-
Geochemical characteristics and hydrocarbon generation potential of Upper Paleozoic source rocks in Ganquan area，Ordos Basin
WEI Xin, TANG Jianyun, SONG Hongxia, CHEN Yubao
2022, Vol.34(6): 92–100
Abstract
(
270 )
PDF (4009 KB) (
254
)
doi: https://doi.org/10.12108/yxyqc.20220608
A number of organic geochemical tests such as organic carbon content determination，rock pyrolysis analysis，kerogen maceral identification and vitrinite reflectance，were carried out on coal measure mudstone， carbonaceous mudstone and coal rock samples of Benxi Formation and Shanxi Formation of Upper Paleozoic source rocks in Ganquan area of Ordos Basin，and the hydrocarbon generation potential was evaluated. The results show that： （1）There are many sets of source rocks developed in Upper Paleozoic in Ganquan area， and the lithologies are mainly coal and dark mudstone.（2）The organic matter of Shanxi Formation has high abundance and it is a good source rock. In contrast，the organic matter abundance of Benxi Formation is low and relatively poor. In terms of organic matter types，the source rocks of Benxi Formation are mainly humic type Ⅲ， while the source rocks of Shanxi Formation are mostly humic type Ⅲ， followed by sapropel-humic type Ⅱ2.（3）The maturity of source rocks of Benxi Formation and Shanxi Formation has been in the stage of high maturity to over maturity. （4）The Upper Paleozoic source rocks are widely distributed in Ganquan area. The cumulative thickness of source rocks of Benxi Formation is 10-20 m，and the cumulative thickness of source rocks of Shanxi Formation ranges from 50 m to 80 m. As a whole， they are relatively high-quality source rocks with high hydrocarbon generation potential.
-
Characteristics and main controlling factors of tight sandstone reservoirs of Permian Shan 2 to He 8 members in southeastern Ordos Basin
MI Weiwei, XIE Xiaofei, CAO Hongxia, MA Qiang, DU Yonghui, ZHANG Qiong, DENG Changsheng, SONG Jiaxuan
2022, Vol.34(6): 101–117
Abstract
(
276 )
PDF (15081 KB) (
311
)
doi: https://doi.org/10.12108/yxyqc.20220609
Based on the analysis and test data of casting thin section， core physical properties， scanning electron microscope，constant-rate mercury intrusion， the micro pore and throat characteristics of tight sandstone reservoirs of Permian Shan 2 to He 8 members in southeastern Ordos Basin were quantitatively and quantitatively evaluated， and the main reasons for the densification of sandstone reservoirs were analyzed. The results show that： （1）The sandstone reservoirs of Permian Shan 2 to He 8 members in southeastern Ordos Basin are mainly composed of quartz sandstone，lithic quartz sandstone and lithic sandstone. The reservoir pores mainly include residual intergranular pores，（particles， cements），dissolved pores， authigenic clay-mineral intercrystalline pores and a small number of microcracks.（2）The pore radius of sandstone with different permeability has little difference， but the throat radius is obviously different. With the increase of permeability， the distribution range of the throat radius becomes wider，and the proportion of the large throat increases， indicating that the permeability is mainly controlled by a relatively small number of large throats.（3）The heterogeneity of the pore structure of the sandstone in the study area is controlled by sedimentary microfacies. The underwater distributary channel sand bodies of delta front have the best physical properties， while distal bar and delta front sheet sand have poor physical properties.（4）Diagenesis is the main controlling factor for the complexity of the microscopic pore structure of the reservoirs in the study area. Long-term continuous burial and compaction resulted in close contact of particles， and part of them were transformed into linear-concave-convex contact under pressure solution，resulting in a large reduction of pore throats. Multi-phase quartz secondary enlargement，and the filling of pores with different types of clay minerals and carbonate cements，further aggravated the decrease in permeability and the densification of the reservoir.
-
Lithology prediction technology and its application of Paleogene Wenchang Formation in Panyu 4 depression，Pearl River Mouth Basin
ZHANG Weiwei, LIU Jun, LIU Lihui, ZHANG Xiaozhao, BAI Haijun, YANG Dengfeng
2022, Vol.34(6): 118–125
Abstract
(
219 )
PDF (4962 KB) (
170
)
doi: https://doi.org/10.12108/yxyqc.20220610
The Paleogene of Panyu 4 depression in the Pearl River Mouth Basin has great exploration potential， and several wells produce oil and gas in Paleogene. The ray elastic impedance was expressed as a function of P-wave impedance and S-wave impedance， and Poisson reflectance data with Poisson impedance meaning were extracted from the gathers. Poisson impedance inversion was carried out through angle scanning sensitive angle stacking data， and the plane distribution of sandstone of Paleogene in Panyu 4 depression of Pearl River Mouth Basin was predicted. The results show that： （1）the lithology of Paleogene Wenchang Formation in Panyu 4 depression is complex， including mudstone，carbonaceous mudstone，siltstone and sandstone. The sandstone is characterized by high Poisson impedance， corresponding to the peak reflection on the seismic profile， and the mudstone is characterized by low Poisson impedance，corresponding to wave trough reflection on seismic profile.（2）Different lithology has different sensitive angles. Through forward modeling and angle scanning of actual data，it is considered that 20°-25° stacking data can highlight the seismic response of sandstone.（3）Sandstone reservoirs are developed in the second， third and fourth members of Wenchang Formation in the study area， the sandstone reservoirs of the third member vary greatly laterally，and the favorable areas are mainly distributed in the east of well A，which is the next favorable exploration target.
-
Reservoir characteristics of the fourth member of Sinian Dengying Formation and its implications for oil and gas exploration in Moxi area，Sichuan Basin
GENG Xiatong, XING Fengcun, YAN Haijun, FU Hui, CHAI Hanbing, LIU Zhibo, CHEN Xiaoquan, GU Qiang
2022, Vol.34(6): 126–140
Abstract
(
286 )
PDF (16196 KB) (
275
)
doi: https://doi.org/10.12108/yxyqc.20220611
Based on the high-precision sequence stratigraphic division and sedimentary facies research， the reservoir characteristics of the platform-margin mound，the back shoal of platform-margin mound and the restricted platform of the fourth member of Sinian Dengying Formation in Moxi area， Sichuan Basin were characterized and compared by using the data of cores， thin sections and imaging logging. The results show that： （1）The fourth member of Dengying Formation in Moxi area can be divided into two third-order sequences，seven parasequence sets and 13 parasequence.（2）Platform-margin mound， platform-margin shoal，inter-mound and shoal were recognized in platform-margin，and restricted platform were divided into inner mound，inner shoal，inter mound，lagoons and restricted subtidal subfacies，then the microfacies were divided further.（3）The reservoir rock type，reservoir space and reservoir type of platform-margin zone and intra-platform area are basically the same and controlled by the highstand systems tract. Two sets of reservoirs are developed vertically，low angle and high angle microfractures are differently developed vertically，and physical properties tend to improve upward.（4）The reservoir space types and physical properties in different facies zones are different. The platform-margin microbial mound has the characteristics of good reservoir physical properties， with microfractures and pores well developed. The development degree of microfractures and pores and physical properties in the development area of back shoal of platform-margin mound is weakened，and it is further weakened in the intra-platform zones. However，there are good reservoirs developed in the restricted platform far from the platform-margin zones.
-
Composite sand body architecture and controlling factors of the lower Minghuazhen Formation of Neogene in northern Qinhuangdao 32-6 oilfield
REN Mengyi, HU Guangyi, FAN Tingen, FAN Hongjun
2022, Vol.34(6): 141–151
Abstract
(
260 )
PDF (7007 KB) (
206
)
doi: https://doi.org/10.12108/yxyqc.20220612
Through logging，dominant seismic attribute fusion， spectrum attribute trend analysis and other methods， the reservoir architecture characteristics of the composite sand bodies in the second oil group（NmⅡ）of the lower Minghuazhen Formation of Neogene in northern Qinhuangdao 32-6 oilfield were studied，and the control effect of base-level cycle on the composite sand body architecture was clarified. The results shows that： （1）The composite sand bodies of the NmⅡ in northern Qinhuangdao 32-6 oilfield are mainly point bar and crevasse splay deposits，and the seepage barrier is mainly floodplain and abandoned channel deposits. According to logging facies and sand body structure rhythm，the internal structure of composite sand bodies is divided into box shape in the head and middle of point bar，bell shape in the end of point bar，funnel shape in crevasse splay，peak shape and low-amplitude tooth shape in floodplain and abandoned channel. The external stacking patterns of the composite sand bodies include isolated type，tight lateral stacking type，scattered lateral stacking type and stacking type. （2）In the early stage of NmⅡ，the intertwined channel mainly deposited point bar and crevasse splay. Sand bodies of tight side-stacking type and stacking type were widely developed. In the late stage of NmⅡ，the channel evolved into single band shape，and the crevasse splay was sporadically distributed on the convex bank of the channel. The scale of the composite sand bodies became smaller，mainly scattered lateral stacking type and isolated type，and the floodplain and abandoned channel became the seepage barrier between the composite sand bodies. （3）In long-term to middle-term cycles in the study area，heterocyclic factors such as tectonic activities affect the external morphology and stacking of composite sand bodies by adjusting the accommodation space and sediment supply，while in short-term cycles， the internal structure of sand bodies is affected by autogenetic cycle such as sediment types and hydrodynamics.
-
Formation mechanism and percolation characteristics of secondary foamy oil by gas injection in super heavy oil
LU Yingbo
2022, Vol.34(6): 152–159
Abstract
(
235 )
PDF (3791 KB) (
209
)
doi: https://doi.org/10.12108/yxyqc.20220613
In order to explore the formation mechanism， percolation characteristics and displacement effect of foamy oil in super heavy oil reservoir， the oil and reservoir parameters of Jurassic Qigu Formation in Wuxia fault zone in the northwestern margin of Junggar Basin were used to select gas injection medium for foamy oil formation and carry out the testing experiment of bubble point pressure of crude oil. The gas injection microscopic visualization and sand-filling pipe displacement experiments were carried out to analyze the percolation characteristics of foamy oil formed by gas injection， and the oil displacement effect of gas injection foamy oil was evaluated. The results show that： （1）The bubble point pressure of the crude oil of Jurassic Qigu Formation in Wuxia fault zone in the northwestern margin of Junggar Basin is 9.7 MPa. The pseudo-bubble point pressure increases with the increase of gas injection volume and temperature， the pseudo-bubble point pressure at 50 °C increases with the increase of CO2 injection，and the pressure rises slowly. The reservoir has good gas injection characteristics. （2）The flow of foamy oil in the study area can be divided into five stages：no bubble stage， bubble precipitation stage， bubble expansion stage，bubble coalescence stage and bubble extinction stage.（3）The recovery of steam+ CO2 flooding is 13.3% higher than that of pure steam sand-filled pipe flooding. With the release of pressure，the number of bubbles increases gradually， and the oil production increases gradually. When the pressure drops to the bubble point pressure，the number of bubbles tends to be stable and form relatively stable foamy oil，and the oil production increases greatly，which is the main oil production period. When the pressure is released to the pseudobubble point pressure，the number of bubbles will decrease rapidly，the foam oil will disappear gradually，and the oil production will decrease slowly.
-
Profile change rule during Cr3+ polymer weak gel flooding and related improving method
XIE Kun, SU Cheng, LIU Changlong, MEI Jie, YU Haitao, HE Xin, LU Xiangguo
2022, Vol.34(6): 160–170
Abstract
(
187 )
PDF (4754 KB) (
179
)
doi: https://doi.org/10.12108/yxyqc.20220614
The Cr3+ polymer week gel with molecular intra-crosslinking was used to study the influences of slug size， core permeability and crude oil viscosity on reservoir absorption profile and production profile by core displacement experiment. The experiments of plugging/profile control/flooding were carried out in Oligocene Dongying Formation in LD10-1 block of Bohai Oilfield. The results show that： （1）The slug size of profile control agent has no effect on the turning of fluid flow at both ends of injection and production and the turning time of profile，but when the slug size per unit volume exceeds 0.3 PV，the increase rate of Cr3+ polymer weak gel to enhance crude oil recovery decreases. With the increase of reservoir permeability ratio and crude oil viscosity，the turning time of fluid flow at both ends of injection and production is delayed and the turning time of profile is advanced.（2）Three measures including organic and inorganic composite gel system plugging high permeability layer，polymer microspheres regulating micro heterogeneity， and heavy oil mobility improver improving oil displacement efficiency，can be implemented at the same time，which can improve the recovery after polymer weak gel profile control and flooding.（3）The EOR mechanism of plugging/profile control/flooding combination is： plugging the dominant seepage channel to expand the macro swept volume of heterogeneous reservoir， bridging and blocking polymer microspheres in variable diameter pores or throats to realize micro fluid flow diversion， and high-efficiency oil displacement agent can enter the unswept pore throat area to play three roles， including reducing viscosity crude oil， reducing oil-water interfacial tension， and high-efficiency displacement.