10210SP is second commitment exploration well in Blocks 10210 10610 drilled by PetroVietnam Exploration Production Corporation (PVEP) after the first well 10610HRN1X spudded on 26th November 2013. There are 07 offset wells in the Blocks 102 106 with 03 discovery of oil and gas, such as Ham Rong oil field, Thai Binh gas field and Yen Tu oil discovery. The Sapa prospect is located in the middle and the same trend with 2 gas discoveries which are Thai binh and Bach Long discovery. It is an elongate in NWSE direction, faulted anticlinal closure at Middle Lower Miocene and Upper Oligocene (Figure 1). The targets of the 10210SPwell are to explore the hydrocarbon presence in Middle Miocene (U220), Lower Miocene (U240, U260) sandstone (as primary targets), and Upper Oligocene (U300) sandstone (as secondary target). At the proposed location, the well will be drilled vertically to the final well total depth inside Oligocene. Sapa is first ranking prospect in gasbearing clastics play, with the estimated GIIP about 1320 Bscf. Total depth (TD) of the 10210SPwell is planned at 2420mTVDss2450 mMD. The final TD, however, will be determined based on the well TD criterion which is mentioned in detail in section 4.7. Two DSTs are planned to test the primary targets as Middle Miocene and Lower Miocene sandstone formations. Ultimately, the well will be plugged and abandoned. Exploration activities in the area began in 1978 with analog seismic acquisition. After that, PETROVIETNAM acquired additional regional 2D seismic surveys. In 1988, TOTAL entered a PSC over the area covering Block 106, parts of 102, 103 and 107. During this exploration stages, TOTAL acquired about 9200 km 2D seismic data with 60 fold full coverage. The grid spacing this 2D survey are 4 x 4km in the NE part and 2 x 2km in the central part of Block 106. TOTAL relinquished this area in 1991 without drilling any well in Blocks 102 106. IDEMITSU signed the PSC for Block 102 in June 1992 and conducted about 2270 km 2D seismic data. In 1994, they drilled two wells, 102CQ1X and 102HD1X. Both wells were unsuccessful and they relinquished the PSC in September 1995. PCOSB farmedin into the Blocks in Feb. 2003 and subsequently acquired 450 sq.km of new 3D seismic over the Yen Tu Ha Long structural complex area. Based on the 3D seismic data, the first exploration well, 106Yen Tu1X, drilled in September 2004 by PCOSB to test the preTertiary fractured karstified carbonate rock play and MioceneOligocene stratigraphic plays. The result was about 2.9m net oil sand encountered in Middle Miocene U210 sand with average porosity of 18.0% and average SW of 57.0%. The 106Yen Tu1X was the first oil discovery in offshore northern Vietnam and has proven the existing of petroleum system (oil) in Song Hong basin. The DST1 in carbonate basement revealed the presence of gas but is inconclusive with regards to hydrocarbon properties due to an immature test. The test was abandoned early due to the high level of H2S to surface during lifting. In 2005, PCOSB conducted two additional new 3D seismic surveys with 284 sq.km in block 106 and 320 sq km in block 102. In 2001, PCOSB drilled the first exploration well (106Ha Long 1X) in Block 106, to explore the PreTertiary fractured and karstified carbonate play and MioceneOligocene clastic play. The well was PA with oil and gas shows in both objectives. In 2004, PCOSB drilled the second exploration well (106YT1X) was spudded to explore the HC of the fractured and karstified carbonate basement and Miocene sandstone. As a result, 2.59 m oil net pay in U210 (oil sample confirmed by MDT) and oil show in basement, but the DST1 perforated in basement was terminated due to excessive level of H2S (2200ppm). The well was plugged and abandoned. In 2006, 102TB1X was the first well in block 102 drilled by PCOSB to explore hydrocarbon in Miocene and Oligocene sandstones. The well was spudded on 30th September 2006 and finished on 28th November 2006. It is a gas discovery in Miocene sandstone. A total of 43 m and 27 m net hydrocarbon zones were encountered in the Middle Miocene (U220) and in the Lower Miocene (U250) sand packages respectively. Two production tests were carried out in these sands. DST1 in U250 resulted 23 MMscfd of gas with 0.5% CO2 no H2S in 12864” choke size. DST2 which was commingled with 1 addon (from 2 sand intervals) resulted 24 MMscfd of gas with 0.5% CO2 no H2S in 12864” choke size. In 2008, 106HR1X (Ham Rong) was spudded on 2nd June with the primary objective was to explore the hydrocarbon potential in the PreTertiary fractured and karstified carbonate basement and clastic reservoirs of the Middle Miocene channel. After 169 executing days with four sidetracks to be drilled, the well was PA with oil discovery in Carbonate reservoir. One production test was performed with flow of 4859 bpd and 7 mmscfpd at choke size 4064”, together with 6.0% CO2 and 18 ppm H2S. In 2009, well 106YT2X was spudded to appraise the up dip potential of the discovered U210A and to explore the undiscovered U210B Miocene clastic reservoirs, and to test the prospectively of the fractured and karstified carbonate basement structure. As a result, the well was plugged and abandoned without HC show in Carbonate reservoir and high water saturation in Miocene sandstone. In 2009, another well to be drilled to explore the PreTertiary Carbonate on Do Son structure, 106DS1X well, from 28th August 2009 to 27th October 2009. Ultimately, dry hole was concluded by 100% water of testing result. In 2009, to explore and appraise the pretertiary carbonate of Ham Rong structure, 106HR2X was drilled on 26th November. The well successfully achieved the well objective through penetrating the PreTertiary carbonate, acquiring wireline electric logs and conducted open hole well test with a natural flow (post acidizing) of 3401.0 bblsday oil, and 4.47 mmscfd gas (6.0% CO2 and 18 ppm H2S) from 3264” choke. In 2010, PCOSB retained two developing areas as Ham Rong and Thai Binh, relinquished to PVN an area of 10,020 sq.km as named as Blocks 1021010610. In October 2011, a PSC between PVN and PVEP was signed, and PVEP is current operator of Blocks 10210 and 10610. In 2012, PVEP carried out a new 3D seismic survey with a volume of 1170 sq.km covered Chi Linh, Vam Co Dong, Sapa and Bach Long Bac prospects. In 2013, PVEP drilled 10610HRN1X to test the HC in PreTertiary fractured carbonate basement. The well was spudded on 26th November 2013 and keep drilling up to date. Table 1 Seismic data and well result summary in Blocks 1021010610
Trang 1WELL PROPOSAL REPORT
102/10-SP Blocks 102/10&106/10 PSC, Offshore Vietnam
EXECUTIVE SUMMARY
102/10-SP is second commitment exploration well in Blocks 102/10 & 106/10 drilled byPetroVietnam Exploration Production Corporation (PVEP) after the first well 106/10-HRN-1X spudded on 26th November 2013 There are 07 offset wells in the Blocks 102 &
106 with 03 discovery of oil and gas, such as Ham Rong oil field, Thai Binh gas field andYen Tu oil discovery The Sapa prospect is located in the middle and the same trend with
2 gas discoveries which are Thai binh and Bach Long discovery It is an elongate in
NW-SE direction, faulted anticlinal closure at Middle & Lower Miocene and Upper Oligocene
(Figure 1).
The targets of the 102/10-SPwell are to explore the hydrocarbon presence in MiddleMiocene (U220), Lower Miocene (U240, U260) sandstone (as primary targets), andUpper Oligocene (U300) sandstone (as secondary target) At the proposed location, thewell will be drilled vertically to the final well total depth inside Oligocene
Sapa is first ranking prospect in gas-bearing clastics play, with the estimated GIIP about
1320 Bscf
Total depth (TD) of the 102/10-SPwell is planned at 2420mTVDss/2450 mMD The final
TD, however, will be determined based on the well TD criterion which is mentioned indetail in section 4.7
Two DSTs are planned to test the primary targets as Middle Miocene and Lower Miocenesandstone formations
Ultimately, the well will be plugged and abandoned
Exploration activities in the area began in 1978 with analog seismic acquisition After that, PETROVIETNAM acquired additional regional 2D seismic surveys
In 1988, TOTAL entered a PSC over the area covering Block 106, parts of 102, 103 and
107 During this exploration stages, TOTAL acquired about 9200 km 2D seismic datawith 60 fold full coverage The grid spacing this 2D survey are 4 x 4km in the NE partand 2 x 2km in the central part of Block 106 TOTAL relinquished this area in 1991without drilling any well in Blocks 102 & 106
IDEMITSU signed the PSC for Block 102 in June 1992 and conducted about 2270 km2D seismic data In 1994, they drilled two wells, 102-CQ-1X and 102-HD-1X Bothwells were unsuccessful and they relinquished the PSC in September 1995
PCOSB farmed-in into the Blocks in Feb 2003 and subsequently acquired 450 sq.km of
Trang 2PCOSB to test the pre-Tertiary fractured karstified carbonate rock play andMiocene/Oligocene stratigraphic plays The result was about 2.9m net oil sandencountered in Middle Miocene U210 sand with average porosity of 18.0% and average
SW of 57.0% The 106-Yen Tu-1X was the first oil discovery in offshore northernVietnam and has proven the existing of petroleum system (oil) in Song Hong basin TheDST#1 in carbonate basement revealed the presence of gas but is inconclusive withregards to hydrocarbon properties due to an immature test The test was abandoned earlydue to the high level of H2S to surface during lifting
In 2005, PCOSB conducted two additional new 3D seismic surveys with 284 sq.km inblock 106 and 320 sq km in block 102
In 2001, PCOSB drilled the first exploration well (106-Ha Long -1X) in Block 106, toexplore the Pre-Tertiary fractured and karstified carbonate play and Miocene-Oligoceneclastic play The well was P&A with oil and gas shows in both objectives
In 2004, PCOSB drilled the second exploration well (106-YT-1X) was spudded toexplore the HC of the fractured and karstified carbonate basement and Miocenesandstone As a result, 2.59 m oil net pay in U210 (oil sample confirmed by MDT) andoil show in basement, but the DST#1 perforated in basement was terminated due toexcessive level of H2S (2200ppm) The well was plugged and abandoned
In 2006, 102-TB-1X was the first well in block 102 drilled by PCOSB to explorehydrocarbon in Miocene and Oligocene sandstones The well was spudded on 30thSeptember 2006 and finished on 28th November 2006 It is a gas discovery in Miocenesandstone A total of 43 m and 27 m net hydrocarbon zones were encountered in theMiddle Miocene (U220) and in the Lower Miocene (U250) sand packages respectively.Two production tests were carried out in these sands DST#1 in U250 resulted 23MMscf/d of gas with 0.5% CO2 & no H2S in 128/64” choke size DST#2 which was
Trang 3commingled with 1 add-on (from 2 sand intervals) resulted 24 MMscf/d of gas with 0.5%
CO2 & no H2S in 128/64” choke size
In 2008, 106-HR-1X (Ham Rong) was spudded on 2nd June with the primary objectivewas to explore the hydrocarbon potential in the Pre-Tertiary fractured and karstifiedcarbonate basement and clastic reservoirs of the Middle Miocene channel After 169executing days with four sidetracks to be drilled, the well was P&A with oil discovery inCarbonate reservoir One production test was performed with flow of 4859 bpd and 7mmscfpd at choke size 40/64”, together with 6.0% CO2 and 18 ppm H2S
In 2009, well 106-YT-2X was spudded to appraise the up dip potential of the discoveredU210-A and to explore the undiscovered U210-B Miocene clastic reservoirs, and to testthe prospectively of the fractured and karstified carbonate basement structure As a result,the well was plugged and abandoned without HC show in Carbonate reservoir and highwater saturation in Miocene sandstone
In 2009, another well to be drilled to explore the Pre-Tertiary Carbonate on Do Sonstructure, 106-DS-1X well, from 28th August 2009 to 27th October 2009 Ultimately, dryhole was concluded by 100% water of testing result
In 2009, to explore and appraise the pre-tertiary carbonate of Ham Rong structure, HR-2X was drilled on 26th November The well successfully achieved the well objectivethrough penetrating the Pre-Tertiary carbonate, acquiring wireline electric logs andconducted open hole well test with a natural flow (post acidizing) of 3401.0 bbls/day oil,and 4.47 mmscf/d gas (6.0% CO2 and 18 ppm H2S) from 32/64” choke
106-In 2010, PCOSB retained two developing areas as Ham Rong and Thai Binh,relinquished to PVN an area of 10,020 sq.km as named as Blocks 102/10&106/10
In October 2011, a PSC between PVN and PVEP was signed, and PVEP is currentoperator of Blocks 102/10 and 106/10
In 2012, PVEP carried out a new 3D seismic survey with a volume of 1170 sq.kmcovered Chi Linh, Vam Co Dong, Sapa and Bach Long Bac prospects
In 2013, PVEP drilled 106/10-HRN-1X to test the HC in Pre-Tertiary fractured carbonatebasement The well was spudded on 26th November 2013 and keep drilling up to date.Table 1 Seismic data and well result summary in Blocks 102/10&106/10
Trang 42008 106-HR-1X Oil Discovery in Carbonate
2009 Block 106 106-DS-1X Oil show in Mio.&Oli.
2009 106-HR-2X Oil Discovery in Carbonate PVEP 2012 1170 Block 102-106
Trang 52 REGIONAL GEOLOGICAL SETTINGS AND HYDROCARBON PLAYS
2.1 REGIONAL GEOLOGICAL SETTINGS
2.1.1 TECTONIC ACTIVITIES
Blocks 102/10 & 106/10 with an areas of 10,022 sq.km, are located in the northwest part
of Song Hong Basin, offshore Northern Vietnam (Figure 1) with 650-km long and 150
km wide, sedimentary thickness exceeding 10 km in the basin center
Figure 1 Location map of Blocks 102/10&106/10 and 102/10-SPwell
The Song Hong basin is a Kainozoic sedimentary basin was formed as a NW-SE
pull-apart graben and controlled by lateral motion faults such as Song Lo, Song Chay faults It
is believed that the collision between Indochina and Eurasion plates caused clockwiserotation and pull-apart activities in Eocene – Early Oligocene were main tectonic reason
to create the Song Hong basin Then, Song Hong basin had been undergoing tectonicinversion in through Middle-Late Miocene and continuously undergoing thermalsubduction until present (Nguyen Manh Huyen, 2007) It is a complicated basin in ahistorical development from Paleogene time to now, Song Hong basin had been takingtensional-compressional phase, inversion, erosion-truncation, and thermal subduction
Trang 6Therefore, the Song Hong basin has many structural units but it is divided into 3 main
zones in block 102/10-106/10 (Figure 2) as following:
- The South West marginal zone: located on the southwest of song Chay fault andbelongs to Thanh Nghe Monocline with complexes of Protenozic metasedimnets andpredominantly Mesozoic carbonate, Mesozoic clastics and approximately 2,000m inthickness of Kainozoic sediments
- The Central zone: Located in between Song Lo fault and Song Chay fault and itshould be concerned as Miocene inversion zone This area was inversion from MiddleMiocene to Late Miocene, even some parts in the early Pliocene Origins of thisinversion due to right lateral motion of Song Hong fault so that Miocene sedimentswere compressed, lifted and truncated several hundred meters to thousand meters
- The North East Marginal Zone: located in the Northeast of the Song Lo fault with anddivided into Ha Long shelf and Bach Long Vi Zone Ha Long shelf is a Paleozoicbasement covered by approximately 2000m of Kainozoic sediment and characterized
by block to fissle carbonate, sericite, quartzitic sandstone in basement, fine to mediumsandstone in clastics, Ha long shelf has narrow grabens along Song Lo fault withcarbonate buried hills inside and basement highs such as Yen tu- Chi Linh In addition,Bach Long Vi zone was affected by tectonic inversion from Late Oligocene to EarlyMiocene to create prospects in Oligocene to Miocene which distribute in narrowgrabens
Sapa prospect is placed in the Central zone
Figure 2 Three main structural units in Blocks 102/10&106/10
Trang 72.1.2 STRATIGRAPHY
The general stratigraphy of Block 102/10&106/10 includes Pre-Tertiary Basement and Cenozoic sediments
PRE-TERTIARY BASEMENT (Figure 3)
Pre –Tertiary Basement lithology consists of few components as:
- Clastic sedimentary rocks in late diagenetic to easliest metamorphic sequences:Quartzitic sandstones (Orthquartzite), (encountered in 106-DS-1X, 106-HR-1X, 106-YT-1X)
- Clastic sedimentary rocks are dark brown to red brown siltstones and claystone, (encountered in the bottom part of 106-HR-2X)
- Limestone: bedded limestones (encountered in HR-2X), thick bed to massivelimestone (encounterd in 106-HL-1X, 106-YT-1X, 106-DS-1X, 106-HR-1X/2X),dolomitic limestone (encounterd in 106-YT-2X, 106-DS-1X)
Based on the studied results in onshore, it is prognostic that the Pre-Tertiary basementable to consist of clastic sediments with the age of Mesozoic or older
Figure 3 General Pre-Tertiary Stratigraphic Column of Block 102/10&106/10
CENOZOIC SEDIMENT (Figure 4)
Base of Cenozoic (U500) to Base of Miocene/Top of Oligocene (U300)
Phu Tien formation (Eocene)
The rifting of the Pre Tertiary rocks due to transtensional strike slip movement in the lateEocene time has caused the Pre Tertiary rocks to form horsts and grabens During theinitial rifting stage most of the area was exposed to subareal erosion and only small
Trang 8derived coarse clastics such as conglomerate or carbonate talus accumulated near majorfault scarps as graben continued to deepen Alluvial fans developed along the northernfault boundaries Some of these fans were later evolved into fan deltas as regionalsubsidence continues Lacustrine shale is believed to be the main source rock thatgenerate and expel hydrocarbon in the Song Hong basin and surroundings.
Dinh Cao Formation (Oligocene)
As the subsidence continues and the basin deepen, the isolated lakes opened out orevolved into marginal marine or shallow marine environments This section is thetransition from lacustrine to shallow marine environments The deposition is dominated
by the fluvial, deltas to shallow marine This sequence has been uplifted and inverted bycompressional force released in conjunction with the opening of East Vietnam Sea duringthe Late Oligocene time As a result, many structures for hydrocarbon traps are formedand a significant amount of the section has been eroded and truncated to leave major
angular unconformity U300.
Oligocene sediment unconformably overlies the Eocene PhuTien formation Oligocenesediments were encountered in 102-CQ, 102-TB, 106-HR-1X, 106-YT-2X
Lithologically, the Oligocene sediment composes of grey to dark grey siltstone andlacustrine claystone intercalated with sandstone and occasional alluvial conglomerates.Spores and pollen including Cicatricosisporitesdorogensis and
FlorschuetsiaTrilobatadefines the Oligocene age and Viviparuspresence is an indicator
for fresh water lake conditions The Oligocene shale is a prolific source rock
Base of Miocene/ Top of Oligocene (U300) to Top of Lower Miocene (U240)
Phong Chau Formation (Lower Miocene)
In Early Miocene, the left-lateral movement of the Song Hong Faults entered theterminative period Concurrently, in the margin of Vietnam-China Plate, the rifting andsubsidence movement was also weakened to terminate the rifting phase The rapid rise ofthe sea level completely changed the environment from lacustrine to shallow marine.The Lower Miocene sediment consists of fine-grained, rippled and mottled beddedsandstone intercalated with dark-darkgrey claystone and siltstone Glauconite has beenfound in many thin sections in this sequence Spores and pollen are represented by
BentulaAlnipollenites, FlorschuetziaLevipoli, and UlmusUndolosus.
Top of Lower Miocene (U240) to Top of Middle Miocene (U200)
Phu Cu Formation
Middle Miocene was started with the post-rifting phase, the basin was subsided and thesea level dropped significantly during Middle Miocene, lead to the rate of sedimentsupply outpaced the rate of creation of new accommodation space When the rate ofrelative sea level fall is greater than rate of subsidence part of the shelf will exposed and
Trang 9active erosion taken place on the shelf The eroded sediment will be deposited in thedeeper part of the basin.
Lithological, The formation consists of grey sandstones, claystones and siltstones Thesand is fine-to-medium grained litharenites with a high content of quartz Glauconite iscommon in distal areas It is considered as a relatively good reservoir Overall goodporosity is obtained from the log interpretation results, varying from 13% to 19% Ingeneral, the reservoir quality drops significantly with increasing depth This sequenceprovided main productive reservoirs in Blocks 102/10&106/10 (TB-1X, YT-1X) as well
as surrounding area
Top of Middle Miocene (U200) to Top of Upper Miocene (U100) (or Base Pliocene Unconformity)
Tien Hung Formation (Upper Miocene)
The Late Miocene inversion initiated by the strike slip activity along Song Hong faultsystem caused this section had been uplifted, eroded and formation of significant
unconformity (Base Pliocene Unconformity U100).
The main characteristic of Tien Hung sediment is containing a considerable number ofcoal seams, varying from 0.5m to more than 10m thick The lithological componentsconsist of sandstone, minor pebbly sandstone and gravelite (upper part) interbedded withsiltstone, coal, coaly shale and shale (lower part) The sandstone is weakly consolidated,medium to very coarse grained, moderately to well sorted and with fair to very good
reservoir quality Spores and pollen are represented by Dacrydium Ilex, Quercus,
Fl.Trilobata; among the foraminifera are Pseudorotalia, and Ammonia.
Top of Upper Miocene (U100) to Present
The Vinh Bao, Kien Xuong, Hai Duong formation
The sediment consists of unconsolidated, moderately well-sorted, fine-medium grainedsands and silts interbedded with soft, plastic clays It deposited in a coastal plain toshallow marine environment because it contains an abundance of marine forams
(Globorotaliahumerosaof N18-N19 zone), nannofossils, molluscs and other fossils as
well as Glauconite
Trang 10Figure 4 General stratigraphic column of Cenozoic sediments in Central Zone of
Northwest Song Hong Basin, Blocks 102/10&106/10
2.2 HYDROCARBON PLAYS
Two main hydrocarbon plays can be recognized in Blocks 102/10&106/10, namely:
- Oligocene and Miocene Inversion Sandstones Play (Table 2)
- Pre-Tertiary karstified and fractured Carbonate Basement Play (Table 3)
The play schematic and elements of the Tertiary inversion play and the Pre-Tertiary play
are shown in Figure 5.
Trang 11Figure 5 Hydrocarbon plays concept schemetic in Northwest Song Hong
Basin, Blocks 102/10&106/10
Table 2 Tertiary Inversion Sandstones Play
Reservoir Lower-Middle Miocene sandstones and Oligocene sandstones
Source Rocks Mudstone/coaly shale of Eocene-Oligocene and hydrogen-rich coal
and coaly shale of Lower Miocene
Seal Lower to Upper Miocene inter-bedded shale
Late trap formation with respect to hydrocarbon generation: theMain Risk structure formed 5-10 M.A and HC generation and migration maypre-date the trap formation.
Sealing ability of fault and quality of reservoir
Table 3 Pre-Tertiary karstified and fractured Carbonate Basement Play
Reservoir Carboniferous-Permian karstified and fractured carbonate andpossibly other Pre-Tertiary rocks.
Source Rocks Eocene-Oligocene lacustrine shales in adjacent half graben
Seal Late Middle Miocene Sequence of inter-bedded grey shale Directlyseal above Carbonate reservoir is Oligocene shale.
Main Risks The main risks are presence and distribution of carbonate,effectiveness of porosity.
Trang 123 SEISMIC INTERPRETATION
3.1 SEISMIC DATA
Sapa structure is covered by the 2012 3D seismic survey, which was acquired by PVEPfrom 27 July to 06 September 2012 using M/V Amadeus with a dual sources and 8streamers configurations The main acquisition parameters contain Source volume of3,460 cubic-in with 6000m streamer length, Bin size of 6.25m x 25 m and 80 foldcoverage Total 1,170 square km was acquired in this survey
The dataset was processed by Fairfield Vietnam Ltd by Anisotropic Pre-Stack TimeMigration (APSTM) technology The APSTM processing was completed in February
2013 with fair to good data quality for both the clastic and Basement objectives This 3Ddataset was used for seismic interpretation and well design of Sapa prospect with reversepolarity and SEGY format
3.2 SEISMIC-TO-WELL TIE
The 107-BAL-1X was drilled in Block 107, but covered by the 2012 3D seismic survey.Therefore it is the main well used for seismic to well tie Another offset well, 102-TB-1Xwas also correlated in the seismic interpretation
Synthetics seismogram of the 107-BAL-1X well shows confident seismic-well tie in
Figure 6.
Figure 6 Synthetic seismogram from BAL–1X well
Trang 13Figure 7 Synthetic seismogram from TB–1X well
Table 4 Seismic characteristics of respective horizons
Trang 143.3 SEISMIC INTERPRETATION
Seismic interpretation and mapping has been carried out using Landmark Decision SpaceDesktop software There are 06 seismic horizons were interpreted in this dataset withcorrelation from the 107-BL-1X and 102-TB-1X offset wells Interpreted seismic sections
are shown in Figures 8-10.
Intra Middle Miocene Unconformity U220, Top LowerMiocene U240, Top Intra Lower Miocene U260 and Top Oligocene U300 maps (Figures 11- 12).
Figure 8 Interpreted arbitrary seismic section through SP structure
Figure 9 N-S seismic section through Sapa structure
Sapa structure is closured at the Top
Trang 15Figure 10 W-E seismic section through Sapa structure
Figure 11 Time structure map of U300 and U260 of Sapa area
Trang 16Figure 12 Time structure map of U240 and U220 in Sapa area
Figure 13 Time structure map of U100 in Sapa area
Trang 173.5 GEOPHYSICAL UNCERTAINTIES
Tectonic activities in the Oligocene inversion and Early Miocene inversion may causeseismic interpretation uncertainties, such as seismic correlations, horizons picking,variance of seismic velocity, time to depth conversion of the structure maps, etc
Figure 14 Interpreted arbitrary seismic section through Sapa structure
4 PROSPECT EVALUATION AND WELL DESIGN
4.1 STRUCTURE
Sapa prospect is the most prospective for drilling in Block 102/10 where was believed to
be on the same gas trend Thai Binh-Bach Long discoveries The Sapa structural closuresare defined in the maps of Top Intra Middle Miocene - U220, Top Lower Miocene -
U240, Top Intra Lower Miocene - U260 and Top Oligocene - U300 (Figures 15-18),
those structural anticline traps against the Song Lo fault which form elongated NW-SEdirection
Trang 19Figure 18 Depth structural map of Top Oligocene U300
The structural parameters are summarized as below table:
Table 5 Geometrical parameters of targets in Sapa Prospect
Trang 20Crest SPP Relief S Horizon depth depth
Source rock evaluation for the wells is mainly based on the geochemical studies
carried out by VPI and PETRONAS in 2004, and updated by PVEP in 2012 The main
conclusions from these geochemical studies are as follows (Figure 19):
Source rocks are present in the Eocene-Oligocene and the Lower-Middle Miocene sequences
The Eocene-Oligocene source rocks mainly consist of Type I/II organic matters of lacustrine and fluvial origin, deposited in the basin depo-center TOCs range from 1.5%-5% and HI index 300-500mg/g The oil and gas discoveries in the
surrounding areas prove this type I/II kerogens have generated and expulsed oil and gas from the kitchen area
The Lower-Middle Miocene sources rocks are also predominantly Type II/III kerogen which can generate oil and gas These source rocks consist mainly of coals, claystones TOCs range from 0.5-2% (coals up to 60%), HI Index 100-200 mg/g
The richness of source rock varies from fair to good
Figure 19 Blocks 102/10-106/10 geochemical study result