Saudi Arabia this year is completing its expansion of production capacity and developing recent discoveries to enhance export flexibility.
The 3 million b/d capacity expansion to 10 million b/d, announced in 1989, is on target for completion by yearend 1994. Most of the effort involves restoration of mothballed production equipment and installation of several gas-oil separation plants (GOSPs) in existing fields.
But Saudi Arabian Oil Co. (Saudi Aramco) also this year will start up production of extra-light oil from a new field in the central part of the kingdom. Aramco will offset the 150,000 b/d of "Arab Super-Light" crude from Hawtah oil field by reducing flow of medium and heavy oil from the Eastern Province, the main producing region.
Start-up of Hawtah area production demonstrates success of an oil search Aramco began after receiving exclusive exploration rights to nearly all of Saudi Arabia's prospective area in 1986. The Red Sea coastal sedimentary zone, with associated marine areas, was added later.
The Hawtah trend comprises at least nine discoveries in the central region south of Riyadh.
Aramco also has disclosed an oil discovery in what had been considered a gas-prone Red Sea coastal region near Midyan, at the mouth of the Gulf of Aqaba in the northwestern part of the kingdom. And it is still evaluating an earlier, large, light-oil discovery in the Empty Quarter on the border with Abu Dhabi.
From new fields and traditional producing areas, therefore, Saudi Arabia has the potential to expand production capacity beyond 10 million b/d. There has been speculation that the next step might be to 13 million b/d, which Saudi reserves of 260 billion bbl certainly could support.
Officials of the Ministry of Petroleum and Mineral Resources, however, say no plans exist for expansion beyond 10 million b/d.
This year, attention within the kingdom focuses on reductions following an 18% government budget cut to 160 billion Saudi rivals ($42.66 billion at mid-May exchange rates) for the current fiscal year.
THE CAPACITY BUILD
Saudi Arabia originally set a flexible schedule for raising maximum sustainable production capacity to 10 million b/d. But in August 1990, after Iraq invaded Kuwait, the government changed plans.
To make up for export volumes lost from Iraq and Kuwait, the kingdom pushed production from 5.3 million b/d before the invasion to 7.5 million b/d in September. And Aramco began an emergency capacity increase that by the following December would take sustainable production to more than 8.5 million b/d.
The capacity push included demothballing of 17 onshore GOSPs and associated pumping facilities (OGJ, Dec. 2, 1991, p. 49). Before the invasion, Saudi Arabia had 31 GOSPs in operation and 26 old or partially built GOSPs mothballed.
In addition to adding more than 2 million b/d to production and 1 million b/d to sustainable capacity on an emergency basis, the kingdom accelerated the timetable for meeting the original 10 million b/d target. The new target was the end of 1994.
That work is nearly complete, according to Petroleum Ministry officials. Saudi production nevertheless remains at 8 million b/d, the quota assigned the kingdom by the Organization of Petroleum Exporting Countries.
Of current Saudi production capacity, Aramco soon will account for 10 Million b/d.
In addition, Saudi Arabia has a 50% share of production from the old Neutral Zone, recently about 380,000 b/d gross.
Early this year, the U.S. Embassy in Riyadh reported details of the capacity build-up in a survey apparently based on Aramco and press reports. The expansion effort, it said, focused on restarting shut-in facilities, rapidly building GOSPs, and adding water injection capacity. Aramco's plans called for drilling of 226 development wells and recompletion of 208 wells.
WHAT'S BEEN DONE
In the northern offshore area, Aramco has added two GOSPs and improved a gas compression plant and a central utilities unit in Marjan field, developed in the 1980s but mothballed before production start.
It also added gas compression facilities and a central utilities plant in supergiant Safaniya field, as well as wet crude handling equipment in Zuluf field.
Recently Aramco has been considering mothballing at least two Zuluf GOSPs with combined capacity of 430,000 b/d of Arab Medium crude. The aim is to allow for increased production of lighter crudes elsewhere. Aramco officials say they'll be able to restart the mothballed gear quickly when price differentials favor production of heavier oils.
In the onshore southern area, capacity work concentrated on two areas of supergiant Ghawar field.
It included construction of two GOSPs, each with capacity of 300,000 b/d, at Uthmaniyah. Two GOSPs in the Hawiyah area were expanded to 300,000 b/d each, taking Hawiyah capacity to 900,000 b/d.
Work also included expansion of a seawater treatment plant at Qurayyah and seawater injection facilities at Ghawar. Development of Hawtah area fields in central Saudi Arabia includes construction of one GOSP and injection stations, The fields will be linked to the East-West crude oil pipeline to the Red Sea at a point west of Riyadh.
Hawtah is to be brought on stream at 150,000 b/d, but the GOSP will be large enough to handle additional crude when required.
CRUDE TYPES, CAPACITIES
At the end of 1993, Aramco's production capacity totaled an estimated 9.7 million b/d.
Of that, 5.5 million b/d was Arab Light (34.5 gravity), 1.8 million b/d was Arab Medium (31.5 gravity), 1.5 million b/d was Araby heavy (27.5 gravity), and 900,000 b/d was Arab Extra Light (Berri, 38.5 gravity).
The Saudi share of non-Aramco production capacity from the partitioned Neutral Zone amounted at yearend to 200,000 b/d of 28.5 gravity sour crudes from offshore Hout and Khafji fields and 50,000 b/d of 27.5 gravity sour crude from onshore Wafra field.
According to a study by Ibrahim A.H. Ismail, head of the energy section at the OPEC Secretariat in Vienna, Saudi Arabia's expansion program will add 2.685-2.935 million b/d to production capacity, before natural declines, by 2000 (OGJ, May 2, p. 95).
The estimate includes expansions in offshore Manifa and onshore Abqaiq and Shaybah fields not expected to start up until 1995 or later. Without natural declines, the additions would push capacity to 11.3 million b/d by 2000. Net of natural declines, capacity will stay at about 10 million b/d into the next century.
Capacity additions cited in Ismail's study are Marjan, 500,000 b/d of Arab Medium; Hawiyah (Ghawar), 500,000 b/d of Arab Light; Zuluf, 700,000 b/d of Arab Medium; Hawtah, 170,000 b/d of 49.5 gravity. "Arab Super-Light" crude; Shaybah, 350-600,000 b/d of 42.5 gravity crude; Manifa, 300,000 b/d; and Abqaiq, 165,000 b/d of Arab Extra-Light.
The additions will be partly offset by deliberate capacity reductions totaling an estimated 600,000 b/d, apparently undertaken for economic reasons, from shut-downs or development suspensions of Khursaniyah, Harmaliyah, Abu Hadriya, Khurais, and Farzan fields.
The Shaybah capacity is uncertain. The field is another potential source of light, sweet crude for the kingdom. Believed to hold at least 7 billion bbl of 42.5 gravity, 0.5% sulfur oil, its northern tip extends into Abu Dhabi, where it is known as Zararra.
But Shaybah is far from existing infrastructure, and Aramco appears to be in no rush to develop it. A 3 year, 3D seismic survey of the field was to have been completed during the first half of the year. Results haven't been disclosed.
CENTRAL REGION
Aramco discoveries since the late 1980s attest to the kingdom's potential outside of the original, Eastern Province concession area. Indeed, as recently as May 1993, more than 70% of the country outside the original concession remained unmapped.
Among the most recent discoveries are 1 Nasla, 175 km south of Riyadh, which tested an average of 2,335 b/d of 50.4 gravity oil, and 2 Um al-Jarf 230 km south of Riyadh, which flowed 2,099 b/d of 53.4 gravity oil. In addition to the region's oil strikes, Aramco has discovered sweet gas and condensate in a field designated Hilwah north of Hawtah.
Geological details on some of the recent strikes emerged in papers delivered at the Geo '94 conference held during April in Bahrain.
The Hawtah area of central Saudi Arabia is the only development project under way outside the traditional producing area.
The main pay in the June 1990 strike is Late Permian Unayzah, which lies unconformably below Permian Khuff, also productive in the region. The Unayzah reservoir occurs in both the Unayzah and Khuff formations. The unconformity between the Unayzah and khuff formations appears as thick caliche and soil horizons.
The reservoir rocks have total porosity of 8-22%, of which 6-15% is secondary porosity created from grain and cement dissolution before oil migrated into place. Unayzah rocks include red conglomerates, sandstones, siltstones, mudstones, caliche, and nodular anhydrites.
The Unayzah was deposited as coalescing alluvial fans dominated by braided streams grading into playa lakes under and to semiarid conditions. Aramco geologists also suspect aeolian processes played important roles in deposition and are integrating data supporting the assumption into a 3D geologic model to be used in reservoir simulation.
Seismic data and structural map geometries indicate wrench faulting of the Paleozoic section in the region, with associated drape and drag of overlying Mesozoic strata. Integration of seismic, magnetic, and gravity data suggests a bifurcating fault system more than 400 km long. The western edge of the system follows a possible suture in the Arabian Plate. Reaction of faulting along the suture during late Carboniferous through Jurassic created a right-lateral strike-slip fault system and formed structures capable of trapping hydrocarbons.
The presence of strike-slip faulting is supported by more than 1,500 km of 2D seismic data, 790 sq km of new 3D data, and 16,000 sq km of magnetic and gravity data.
As it has done in its old fields in the Eastern Province, Aramco has made great use of 3D seismic in the new fields of Central Saudi Arabia. In the Ghinah/Umm Jurf area south of Hawtah, 3D seismic improved drilling success rates for wells flowing more than 2,000 b/d to 83% from 43%. It also overhauled structural interpretation. The first well drilled in Umm Jurf, in 1991, encountered sand but was dry.
Immediately north in the Ghinah area, Aramco was able to map the braided stream, channel belt sands and floodplain siltstones from seismic character changes in the reservoir interval on vertical sections and horizon slices in the 3D data. From the 3D data, Aramco drilled two productive appraisal wells 3 and 6 km south of Ghinah oil production, one of which in 1993 was classified as the Umm Jurf discovery. Later interpretation, however, showed that Ghinah's field limit included the Umm Jurf structure.
Development well location remains heavily dependent on 3D data for mapping of the sand-prone braid belts.
OTHER AREAS
Elsewhere, Aramco in late 1992 and early 1993 reaped promising results from Midyan basin drilling in the far northwestern part of the kingdom.
Offshore Midyan basin exploration during the 1960s had indicated the area might be prospective for gas, and Aramco was reported to be exploring the region as a possible supply of gas for the Red Sea cities of Yanbu and Jeddah. The 1 Midyan wildcat was indeed a gas/condensate discovery, flowing 45 MMcfd of sweet gas and 1,300 b/d of 55 gravity condensate. A delineation well, 2 Midyan, flowed 55 MMcfd of gas and 1,900 b/d of 58 gravity condensate during production tests. Then the 3 Midyan delineation well tested 2,300 b/d of 39 gravity sweet crude and 19 MMcfd of gas, establishing oil potential in the area. Pay in the Midyan basin is the Lower Miocene Maqna Group. Surface and subsurface data indicate a deep central basin bounded by Precambrian basement on the north and northeast with Cretaceous and Tertiary sediments exposed in an uplift on the northwest along the Gulf of Aqaba.
According to an Aramco author, after the beginning of movement on the Levant transform, the central Midyan basin subsided more than the surrounding Red Sea coastal plain because of depression at the extensional end of a wrench fault. This allowed for deposition of a thick Miocene-Recent section, which includes a thick salt sequence. Presence of salt bodies in the Red Sea region complicates seismic work. Aramco is using a prestack, shot gather, depth migration procedure as an alternative to common-midpoint processing to improve imaging, dip preservation, and amplitude information. The Maqna Group is productive in an apparent gas discovery in the Jizan basin, also on the Red Sea coast far to the south of Midyan.
Aramco's other area of recent exploratory interest is called Kahf, near the town of Jawf in the north-central part of the kingdom west of Midyan. The company tested sweet gas there but apparently hasn't been encouraged by appraisal work.
The recent Saudi discoveries don't come close to the scale of reserves already producing in the Eastern Province. But few discoveries anywhere in the world do that.
The immediate importance of the discoveries lies in the flexibility they provide Saudi Aramco by lightening its range of export crudes. The value of that flexibility will have its first test soon when Arab Super-Light begins to flow.
By contrast, geologic potential underlying those discoveries has barely been tested at all.
Copyright 1994 Oil & Gas Journal. All Rights Reserved.
