TAP­PING THE PO­TEN­TIAL

More than 23 per cent of PDO’s pro­duc­tion is ex­pected from EOR projects by 2025

Oil and Gas - - SPECIAL EDITION -

De­spite the chal­leng­ing eco­nomic en­vi­ron­ment, Petroleum De­vel­op­ment Oman (PDO) is con­tin­u­ing its jour­ney in grow­ing the fu­ture EOR con­tri­bu­tion to oil pro­duc­tion. It is an­tic­i­pated that by 2025 more than 23 per cent of PDO’s pro­duc­tion will come from EOR projects.

PDO is cur­rently op­er­at­ing a range of com­mer­cial-scale EOR projects in­clud­ing chem­i­cal EOR, mis­ci­ble gas in­jec­tion (MGI) and ther­mal ap­pli­ca­tions. Con­cur­rently, PDO is con­tin­u­ing to iden­tify novel EOR tech­nolo­gies that have the po­ten­tial to un­lock dif­fi­cult hy­dro­car­bon re­sources. This is be­ing done through a series of ded­i­cated lab­o­ra­tory and field test­ing pro­grammes, ac­cord­ing to PDO’s Sus­tain­abil­ity Re­port re­leased re­cently.

The Mar­mul Poly­mer Phase 1 project has been run­ning for the last seven years and has de­liv­ered 13.7 mil­lion bar­rels of oil. Phase 2 started in 2015 and in­volves in­ject­ing poly­mer into 19 ad­di­tional in­jec­tor wells, and has de­liv­ered 840,000 bar­rels of oil to date. The av­er­age com­bined pro­duc­tion gain from both phases in 2017 was 5,755 bpd. A to­tal of 14.6 mil­lion bar­rels of oil has been de­liv­ered as a re­sult of poly­mer in­jec­tion in the Mar­mul field to date. In 2017, the fi­nal in­vest­ment de­ci­sion was taken for Mar­mul Poly­mer Phase 3, which tar­gets the in­fill drilling of the ex­ist­ing wells in the Mar­mul Al Kh­lata reser­voir, wa­ter­flood and poly­mer ro­ta­tion. The project will de­velop 80 mil­lion bar­rels of in­cre­men­tal oil, with first oil by Q1 2023. Near mis­ci­ble sour gas in­jec­tion in the Birba field for the past 23 years has yielded an ad­di­tional 50 mil­lion bar­rels, (rep­re­sent­ing a re­cov­ery rate of 22%) for 5.5 bil­lion cu­bic me­tres of gas in­jected so far, and is on tar­get to achieve up

to 45% re­cov­ery from in­fill hor­i­zon­tal drilling and ad­di­tional gas in­jec­tion.

The Har­weel 2AB project started mis­ci­ble gas in­jec­tion in April 2014 at a con­strained rate of up to 1.7 mil­lion cu­bic me­tres per day. This has ramped up to a full-ca­pac­ity in­jec­tion rate of up to five mil­lion cu­bic me­tres per day since Jan­uary 2015 af­ter sep­a­ra­tor re­place­ments. A clear re­sponse to the MGI process has been es­tab­lished in terms of in­cre­men­tal oil rates (in­cre­men­tal oil to date of around 10 mil­lion bar­rels and tar­get pres­sures above the min­i­mum mis­ci­bil­ity pres­sure across the field.) The ex­pected to­tal re­cov­ery with MGI is about 45%.

In­jec­tion in Sakhiya field as part of the Sak mini­flood project has con­tin­ued since mid-2015 with high in­jec­tiv­ity of up to 2.5 mil­lion m3 /d. A pos­i­tive reser­voir pres­sure re­sponse has been ob­served as the de­ple­tion rate slows down. One of the key high­lights in 2017 for mis­ci­ble gas was the start-up of the Al Noor 3A sour MGI pi­lot with pos­i­tive ini­tial in­di­ca­tions, with both in­jec­tor wells ac­cept­ing the tar­get rates.

The ther­mal gas-oil-grav­ity-drainage (T-GOGD) process in Qarn Alam has been un­der­way since late 2011. In 2017, 3.3 mil­lion tonnes of steam were in­jected into the Shuaiba oil-bear­ing for­ma­tion, pro­duc­ing 6.8 mil­lion bar­rels of oil and re­sult­ing in a steam-to-oil ra­tio of ap­prox­i­mately three. Project record lev­els of steam in­jec­tion were achieved with peak rates ex­ceed­ing 15,000 tonnes per day. How­ever, whilst oil pro­duc­tion ex­ceeded ex­pec­ta­tions, to­tal steam in­jec­tion for the year fell short of fore­casts due to gen­er­a­tor and steam in­jec­tor well in­tegrity is­sues cou­pled with pro­longed pro­duced gas com­pres­sor (PGC) out­ages. Re­cov­ery plans are in place to con­tinue the per­for­mance im­prove­ment dur­ing 2018.

The Amal steam project con­tin­ues to im­prove in all ar­eas, and the year­aver­age oil pro­duc­tion for 2017 was 15,716 bpd. There was a con­tin­ued strong steam in­jec­tion per­for­mance with 2017 rep­re­sent­ing the high­est an­nual av­er­age in­jec­tion rate of around 7,700 tonnes per day.

There was im­proved avail­abil­ity of heat re­cov­ery steam gen­er­a­tors in Amal West and more once-through steam gen­er­a­tors in Amal East, and a ther­mal re­sponse has now been demon­strated in both fields. Reser­voir per­for­mance con­tin­ues to im­prove with good cold and ther­mal per­for­mance. Last year, 18 wells were drilled in the Amal West 3.3-acre in­fill project.

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