USGS Open-File Report 99-50D (Total Petroleum

U.S. DEPARTMENT OF THE INTERIOR
U.S. GEOLOGICAL SURVEY

Ghaba Salt Basin Province and Fahud Salt Basin Province, Oman -- Geological Overview and Total Petroleum Systems

By
RICHARD M. POLLASTRO

World Map with Province

Open-File Report 99-50-C

production from 13 wells. PDO has estimated that 45 wells will be in production by the year 2000 and gas production is predicted to peak in 2003 and continue through 2025 to meet contract requirements (Petroleum Economist, 1998). Gas production and operations will be centered around three major fields of the Ghaba SaltBasin: Barik, Saih Rawl, and Saih Nihayda.

TOTAL PETROLEUM SYSTEMS AND ASSESSMENT UNITS

Ghaba Salt Basin Province (2014)

North Oman Huqf/`Q' - Haushi(!) Total Petroleum System (201401)
The North Oman Huqf/`Q' — Haushi(!) Total Petroleum System is interpreted here as the only significant petroleum system of the Ghaba Salt Basin Province in north-central Oman. The first half of the Total Petroleum System (TPS) name implies a combination of all source beds of the Huqf Supergroup in the Ghaba Salt Basin Province. This group of source beds is referred to in this report as those units which generate the `North Oman Huqf'- and `Q'-type oils, as defined by the stratigraphic and geochemical data of Grantham and others (1988), Sykes and Abu Risheh (1989), Richard and others (1998a, b), and Terken (1998; in press). The second half of the system name refers to the Haushi Group, which are the primary reservoirs that produce hydrocarbons from this system. Although numerous reservoirs of various age and lithology are included in this system, approximately two-thirds of the fields produce from the clastic reservoirs of the Carboniferous-Permian Haushi Group. The North Oman Huqf/`Q' — Haushi(!) TPS is summarized in the events chart of figure 8.

Although most of the hydrocarbons produced from the Huqf source rocks are developed only within the salt basins or within the salt itself (for example, the unidentified `Q'-source rock), some source rocks of the North Oman Huqf/`Q' — Haushi(!) TPS are developed locally within Huqf basinal lows (Sykes and Abu Risheh, 1989; Visser, 1991; Lake, 1986; Richard and

others, 1998a, b). The geographic extent of 1) the pod of active source rock, 2) minimum petroleum system, and 3) maximum or Total Petroleum System for the North Oman Huqf/`Q' — Haushi(!) TPS are shown in figure 11. Note that the North Oman Huqf/`Q' — Haushi(!) TPS extends beyond the the Ghaba Salt Basin Province and diagonally across the central portion of the Makaram-Mabrouk high portion of the Central Oman Platform province (2015), into the eastern flank portion of the Rub `al Khali Basin province (2019 ), and southward over the Central Oman High and into the South Oman Salt Basin province (2011). Thus, the boundary over the Makarem-Mabrouk high portion of the Central Oman Platform province (2015) separates fields that are charged by `Q' and North Oman Huqf hydrocarbons generated mostly in the Ghaba Salt Basin proper from fields charged by hydrocarbons generated in the Fahud Salt Basin proper. The minimum petroleum system boundary is defined by known occurrence and distribution of North Oman Huqf-type and(or) `Q'-type oils (Grantham and others, 1988; Sykes and Abu Risheh, 1989; Guit and others, 1995; Al-Ruwehy and Frewin, 1998; Richard and others, 1998a, b; and Terken, 1998; in press) in fields or wells throughout the area and interpreted here as sourced from Huqf rock units deposited within or associated with the greater Ghaba Salt Basin proper. All known oil and gas fields that occur within the minimum petroleum system boundary for the North Oman Huqf/`Q' — Haushi(!) TPS are listed in table 2. The boundary for the Total Petroleum System defines the maximum areal extent of occurrence of genetically-related, Ghaba Salt Basin, Huqf- and `Q'-sourced hydrocarbons. Depth to Huqf source rocks within the TPS boundary likely ranges from about 4,000 m to >10,000 m.

Reservoirs, seals, and trap styles
Names and ages of reservoirs of the North Oman Huqf/`Q' — Haushi(!) TPS and corresponding seals and hydrocarbons produced are summarized in figure 5 and figure 8. The primary reservoirs are two formations of the Middle Carboniferous to Lower Permian Haushi Supergroup - the Al Khlata and