BP’s First Caspian Multilateral Well Buys Time at ACG

BP completed C44, the Caspian’s first multilateral well, 30 days early from the West Azeri platform at Azerbaijan’s mature ACG field. The well is the start of a campaign to put more oil contacts through decks that are already crowded, after the last new platform cost $6 billion.

In the first half of 2026 the Azeri-Chirag-Deepwater Gunashli field averaged 323,000 barrels a day, about 39% of the 823,100 barrels a day it produced in 2010. C44 does not reverse that slide. It is how BP plans to live with it.

A 30-Day Beat on the First Caspian Multilateral

BP, operator of ACG, said on 25 May 2026 that it had put multilateral well technology into the field for the first time. C44, drilled from West Azeri, is the first multilateral well ever drilled in the Caspian. A multilateral well leaves the platform as one hole, then branches so two or more laterals drain separate parts of the rock.

Gio Cristofoli, BP’s regional president for Azerbaijan, Georgia and Türkiye, tied the design to decline management, slot use, and the steel already in the water.

By increasing reservoir contact, improving rig productivity and operational efficiency, as well as optimizing slot utilization while making the best use of existing infrastructure, MLT is a step-change solution for well delivery in ACG.

Gio Cristofoli, BP regional president for Azerbaijan, Georgia and Türkiye

Russell Morrice, BP’s vice president for wells, said C44 was finished with no incidents and that both the drilling and completion phases beat the plan. He called the result a business case for using the design across the field. BP listed C44 among seven oil producers completed in the first half of 2026, alongside three water injectors and two gas injectors.

The 2026 programme is three multilateral wells, including C44 and D41, both of which BP said would come online in the first half of the year. A third well in that batch was not named. More multilateral wells are planned for 2027 and 2028. BP has not published a rate for C44, and it has not said which junction design the well uses.

ACG Production Has Fallen to 323,000 Barrels a Day

BP’s own first-half scorecard is the cleanest picture of where the field sits. Output of 323,000 barrels per day in the first half equalled about 59 million barrels, or 8 million tonnes. Partners spent about $268 million on operating costs and about $733 million on capital, $1,001 million in all. At the end of June, 150 oil wells were producing, with 51 used for water injection and 11 for gas injection.

Full-year 2025 averaged about 330,000 barrels a day, or about 120 million barrels. That is still a long way from 2010, when ACG averaged 823,100 barrels a day and 300.4 million barrels for the year. West Azeri alone made 248,200 barrels a day that year from 15 oil producers and five water injectors.

ACG OIL BY PLATFORM

Central Azeri remains the largest single deck at 88,000 barrels a day. West Azeri, the home of C44, is next at 73,300, less than a third of its 2010 rate. ACE, the new 48-slot platform that started in April 2024, added 26,400 barrels a day, which is 26.4% of the 100,000 barrels a day it was built to process.

Afghan Huseynov, BP’s area development manager for ACG, told the SPE Caspian Technical Conference in November 2025 that output had gone through five to seven years of sharp decline and that the company had held the later drop to around 3% a year. He pointed to a large ocean-bottom seismic programme, more than 20 new injector wells in three years, and horizontal drilling in a basin he called one of the hardest in BP’s portfolio for pressure and fracture gradient. Gio Cristofoli said in June 2026 that the field had produced 4.6 billion barrels of oil “and we think there is more and more to come.”

West Azeri Has 48 Slots and 40-Plus Wells

The binding limit on C44 is not a shortage of oil in the rock. It is a shortage of holes in the deck. West Azeri is a 48-slot production, drilling and quarters platform in 120 metres of water, about 100 kilometres off Baku. First oil moved on 30 December 2005. Crude reached the Sangachal terminal on 4 January 2006.

By the platform’s 20-year mark it had delivered over 1 billion barrels (142 million tonnes), second on the complex after Central Azeri, which had 1.2 billion barrels (157 million tonnes) by 18 February 2025. More than 40 wells and multiple sidetracks have been drilled from West Azeri. In late 2025, 32 wells were active: 24 producers and eight water injectors. About 170 people work on board.

WEST AZERI IN LATE LIFE

• Deck: A 48-slot platform that has already drilled more than 40 wells plus sidetracks.
• Flow: 76,000 barrels a day at the end of the third quarter of 2025, then 73,300 barrels a day in the first half of 2026.
• Old wells: C-06 came on in 2005 at 35,000 barrels a day and has made 80 million barrels on its own.
• Crew: About 170 people, most of them Azerbaijani, including both installation managers.

A single West Azeri well used to do the work of a small platform. C-06’s opening rate of 35,000 barrels a day is more than ACE’s entire first-half average. That is why a design that puts two laterals through one slot is the next tool, not a curiosity. BP’s own statement on C44 named “increasing constraints on available platform slots” as a reason for the change, together with complex formations.

The Last New Platform Cost $6 Billion

The ACG partners sanctioned the Azeri Central East platform in April 2019, the first major investment after the 2017 contract extension. ACE is another 48-slot deck, in about 137 to 140 metres of water between Central Azeri and East Azeri, designed to process up to 100,000 barrels a day and to recover up to 300 million barrels over its life. The price was $6 billion. First oil arrived in April 2024.

Two years later ACE is still a small slice of field output. 26,400 barrels a day is useful, and it will grow as more of those 48 slots are drilled. It is also a reminder of what new Caspian steel costs for a field that already has seven producing platforms and two process platforms. West Chirag, the previous new-build, was itself a $6 billion project sanctioned in 2010, with first oil in January 2014. It averaged 24,000 barrels a day in the first half of 2026.

The 30-day beat on C44 is BP showing partners a cheaper path than a third six-billion-dollar hull. Morrice’s “compelling business case” line is aimed at that comparison. A multilateral well re-uses the rig, the slot, the export line and the people already on West Azeri. A new platform buys 48 more slots and a processing plant, and it takes years to install. For a field at 39% of peak, the well-architecture option is the one that still clears a partnership vote.

What a Multilateral Well Changes Underground

A multilateral well turns one platform slot into two or more drainage paths. The main bore is drilled as usual. A junction is then cut so a second (or third) lateral can leave that bore and reach rock the first hole would miss. On ACG, BP said no single junction type fits every target, so each well will get a setup matched to the local rock, combined with horizontal drilling, geo-steering, and smart completions that include sand control and inflow management.

The industry sorts those junctions by the six TAML junction levels written down in 1997. Level 1 is an open, unsupported split. Level 2 cases and cements the main bore and leaves the lateral open. Levels 3 and 4 add casing, then cement, in the lateral. Levels 5 and 6 add pressure integrity at the junction, either with completion kit or with the casing itself. Cost and risk rise with the number. BP has not said which level C44 uses.

WHAT BP SAYS IT WILL STACK ON THE LATERALS

• Horizontal holes: Already in use at ACG, and now run as branches rather than only as single wells.
• Geo-steering: Tools that keep each lateral in the pay as the rock changes.
• Sand control: Screens and related kit for formations that produce sand with the oil.
• Inflow management: Valves that can choke or shut a lateral if water or gas breaks through.

That last item is the production point. ACG is mature, so water and gas already move through old wells. A junction that lets the operator shut one branch without killing the other is how a crowded slot keeps earning. The same logic is why BP is running a 4D ocean-bottom seismic survey and a subsea intervention campaign on Deepwater Gunashli, with five jobs done in the first half of 2026 and a sixth under way.

First Gas From Under the Oil

The other way to sweat the same steel is gas that was never in the original oil contract. On 1 June 2026 BP and its partners started the first commercial non-associated gas production on ACG, from a well drilled off the existing West Chirag platform into the Qirmaki Upper Sand and Qirmaki Lower Sand, both beneath the oil. BP puts recoverable gas at 4 trillion cubic feet, with upside to 6 trillion. Early flow is a test of the deeper Qirmaki Lower Sand. Gas and condensate go to Sangachal through the oil system already in place.

An addendum signed on 20 September 2024 opened those gas layers and runs to the same 2049 end date as the oil contract. SOCAR is the buyer of gas from the first well. Cristofoli told reporters in Baku on 2 June 2026 that another well was due soon and that the data “could lead to a multi-billion-dollar investment with the gas underneath the ACG reservoir.” A separate oil-rim well from Deepwater Gunashli began drilling in May 2026, with completion expected in the second half of the year.

ACG LATE-LIFE DATES

1. 20 September 1994: Original ACG production sharing agreement is signed in Baku.
2. 7 November 1997: First oil from the Chirag platform.
3. 14 September 2017: Amended agreement extends the field to 2049.
4. April 2019: Partners sanction the $6 billion ACE platform.
5. April 2024: ACE produces first oil.
6. 25 May 2026: BP announces C44 as the first Caspian multilateral well.
7. 1 June 2026: First non-associated gas flows from West Chirag.
8. 3 August 2026: SOCAR buys ITOCHU’s 3.65% interest.

Associated gas is still part of the deal with the state. In the first half of 2026 ACG sent about 11 million cubic metres a day to Azerbaijan, 2 billion cubic metres in total, mainly at Sangachal and also to SOCAR’s Oil Rocks plant. The rest was injected to hold reservoir pressure. Around $45 billion had been invested in ACG by the time the gas addendum was signed in 2024.

SOCAR Now Holds More of ACG Than BP

The party with the most barrels at stake is no longer the operator. On 3 August 2026 SOCAR raised its ACG stake to 35.3% by taking ITOCHU’s 3.65%, up from 31.65%. BP remains operator at 30.37%. The rest of the group is MOL at 9.57%, INPEX at 9.31%, ExxonMobil at 6.79%, TPAO at 5.73% and ONGC Videsh at 2.92%. The price was not disclosed.

Rovshan Najaf, president of SOCAR, used the closing to point at the new gas, not the new well design.

The ACG project has been making a significant contribution to the energy security of Azerbaijan and the wider region for many years. At the same time, the commencement of the first non-associated gas production from the ACG block this year opens up new opportunities for the project’s future development and for further strengthening Azerbaijan’s gas production potential.

Rovshan Najaf, president of SOCAR

The 2017 restated production sharing agreement until 2049 already assigned 75% of profit oil to Azerbaijan. SOCAR’s extra 3.65% of the contractor group sits on top of that. Every barrel that C44, D41 and the 2027-28 laterals hold in the field is a barrel the state now owns more of, and every slot those wells save is a slot that does not need a new $6 billion platform to open.

West Azeri still has 48 holes in the deck, more than 40 wellbores behind it, and a new branch in C44. The contract runs to 2049. The platforms in the water are the ones they have.