Resultados de los ensayos

Torodd Nordlie, Egil Lind and Kristine Rossavik RWE Dea Norge AS

The Titan discovery was made by the 35/9-6S well drilled in November/December 2010 in PL420 in the Northern North Sea approximately 16 km west of the Gjøa Field. PL420 was awarded in APA 2006 and the license is operated by RWE Dea with 30% equity. Partners are Statoil with 40% and Idemitsu with 30%.

The Ryggsteinen Ridge has been underexplored for many years due to poor seismic imaging (complex overburden) and overlooked positive signs from two old wells regarded as

disappointing at the time of drilling (35/11-1 and 35/8-5S). The recent exploration success on Grosbeak, Titan and Skarfjell has changed this picture, and opened up for follow up potential on the Ryggsteinen Ridge and a high exploration activity level.

The primary exploration target for the Titan well was to prove petroleum in Middle Jurassic reservoir rocks (the Brent Group). The secondary exploration target was to prove petroleum in Upper Jurassic reservoir rocks (the Heather Formation) and in the Lower Jurassic reservoir rocks (the Cook Formation).

Oil and gas was proven in the Titan well over a gross column of more than 400 meters at five reservoir levels in the Heather Formation, the Brent Group, the Drake Formation and the Cook Formation. The well was drilled to a vertical depth of 3664 meters and was terminated in Upper Triassic rocks. Several faults were penetrated in the well and have created some uncertainty to the true thickness of the Callovian and Cook reservoir units.

The reservoir levels in the Titan well are in different pressure regimes, and no hydrocarbon-water contacts were encountered. Oil was discovered in the two upper reservoir zones and gas/condensate in the three lower reservoir zones. The PVT modeling suggests that the zones containing gas/condensate will contain oil deeper on the structure. The oil and condensate samples from the five reservoir zones also have comparable geochemical characteristics, so the only difference is the amount of methane.

The Titan well was drilled on a structural closure, and further to the south faults with possible sealing potential are mapped. Since no oil-water contact was penetrated in the well it is uncertain if the discovery is just the four-way structure or if Titan could be a hanging-wall fault trap with a larger areal extension. Due to these uncertainties appraisal drilling is needed to ascertain the volumes of the Titan discovery. The current P50 Titan recoverable resource estimate is 12 million Sm³ of oil equivalents.

A 3D seismic survey (RD1201) was acquired by RWE Dea in the spring 2012. The survey was originally planned for the spring 2011, just after the discovery well, but was one year delayed due to fishery restrictions. As a result of the Skarfjell discovery in PL418 the RD1201 survey was extended into PL418 and PL378. The new 3D seismic data will be used to position the

Titan appraisal well planned to be drilled late 2013 and to map further exploration potential in the PL420 license.

Extended  abstract:    

The  35/9-­‐7,  Skarfjell  Discovery,      The  Skarfjell  Discovery:      

Jens-­‐Ole  Koch,  Sabine  Rössle,  Geert  Strik,  Bernhard  Frey,  Marius  Brundiers  &  Rolf  Magne  Pettersen,   Wintershall  Norge  AS    

The  Skarfjell  discovery  was  made  by  the  35/9-­‐7  well  drilled  in  March  to  April  of  2012  in  PL418  in  the   Northern  North  Sea,  17kms  southwest  of  the  Gjøa  Field.  The  well  found  two  intra  Heather  sandstone   sections  with  light  oil  and  good  reservoir  quality.    The  discovery  is  situated  on  the  Ryggsteinen  Ridge   between  the  Titan  (35/9-­‐6S)  and  Grosbeak  (35/12-­‐2)  discoveries.    

A  stratigraphic  trap  is  formed  by  up-­‐dip  truncation  of  the  intra  Heather  sands  by  an  intra  Volgian/Base   Draupne  unconformity  towards  the  SE  and  a  slope  dipping  towards  the  NE.  The  vertical  height  from  the   mapped  crest  of  the  structure  around  2400m  to  the  mapped  potential  spill-­‐point  is  approximately   600m.  The  majority  of  the  trap  is  situated  in  PL418  but  extends  in  to  the  PL378  towards  the  South.  In  the   largest  scenarioes  the  trap  may  extend  into  the  PL420.  The  area  is  covered  by  an  old  3D  seismic  survey   of  relative  poor  quality  and  a  recent  survey  acquired  in  2012.      

The  two  intra  Heather  sands  consist  of  high  density  gravity  flow  deposits  and  slope  channel  sandstones   deposited  in  an  offshore  marine  environment.  The  upper  reservoir  section  is  of  Middle  Oxfordian  age   whereas  the  lower  section  is  likely  to  be  Bathonian.  The  gross  and  net  reservoir  thickness  is  69/49m  for   the  upper  sand  and  14/6m  for  the  lower  sand.  The  sands  are  deposited  immediately  northwest  and  west   of  the  time  equivalent  shallow  marine  sandstones  of  the  Sognefjord  and  Krossfjord  Formations  in  the   Gjøa,  Fram  East  and  Troll  Fields.    

Both  intra  Heather  sandstones  were  saturated  with  light  oil  of  good  quality  to  the  base  of  the  reservoirs   in  an  ODT  situation.  The  ODT  was  found  260m  below  the  mapped  crest  of  the  structure  in  the  upper   sand  and  360m  below  the  crest  in  the  lower  sand.  Based  on  the  PVT  data  Skarfjell  may  have  a  gas  cap   updip  of  the  discovery  well.  The  oils  in  the  two  sands  have  slightly  different  density  and  composition  and   fall  on  the  same  pressure  gradient  within  one  bar.  

The  Skarfjell  structure  is  cut  by  a  series  of  northwest-­‐southeast  trending  normal  faults  formed  by   extension  during  several  episodes  in  the  Late  Jurassic.  The  faults  are  relatively  short  and  the  reservoir  is   likely  to  be  connected  through  non  faulted  areas  and  across  faults  with  small  throw.  The  faults  are  likely   to  have  been  active  during  deposition  of  the  intra  Heather  sandstones  which  are  generally  thought  to  be   thickening  downdip.    

Due  to  the  relative  poor  quality  of  the  seismic  data  and  the  location  of  the  discovery  at,  or  close  to,  the   shallow  marine  to  offshore  depositional  transition,  there  is  a  significant  uncertainty  on  the  reservoir   distribution,  in  addition  to  the  reservoir  thickness  and  quality.  Furthermore  the  depth  of  the  OWC  is  still   unknown  and  the  presence  and  thickness  of  a  gas  cap  is  uncertain.    

These  uncertainties  are  the  focus  of  the  appraisal  program  which  consists  of  a  Skarfjell  North  appraisal   well  in  PL418  and  a  Skarfjell  South  appraisal  well  in  PL378.  The  main  objectives  of  the  two  appraisal   wells  and  optional  sidetracks  are  to  find  the  hydrocarbon  contacts  and  to  acquire  3-­‐4  reservoir   penetrations  with  a  full  set  of  reservoir  data  including  a  DST  in  one  of  the  wellbores.  

Wintershall  Norge  AS  thanks  the  partners:  Agora  Oil  &  Gas,  Bayerngas  Norge  AS,  Edison  International   Norway  Branch  &  RDE  Dea  Norge  AS  for  permission  to  publish  this  extended  abstract.  

  IH2 ODT 35/9-7 at 2660 m TVDSS

General Spillpoint at 2990 m TVDSS Crest at 2394

m TVDSS P50 GOC 2553 m TVDSS

Constructed  Top  Oxfordian  Turbidites  IH2  Depth  Map                  

35/9-­‐7  CPI   showing  very   good  

reservoir   quality  of   Intra  Heather   Sandstones  1  

&  2.  

  Arbitrary  

seismic  line     from  the   RD1201  3D   seismic   survey  across   the  Skarfjell   Discovery