Geostatistical evaluation of the Hazm Al-Jalamid phosphorite deposit, northwestern Saudi Arabia
[Thesis]
A.-R. M. Jarad
King Fahd University of Petroleum and Minerals (Saudi Arabia)
1996
326
M.S.
King Fahd University of Petroleum and Minerals (Saudi Arabia)
1996
The Sirhan-Turayf Basin contains several phosphorite localities of Late Paleogene age including: the Thaniyat Turayf, Al-Amud, Al-Quraymiz, As-Sanam, Khor Umm Wu'al and Hazm Al-Jalamid areas. The Hazm Al-Jalamid deposit is apparently the most attractive on due to its exceptionally high grade and thickness. This deposit is found in two, distinctive, phosphorite horizons (Horizon 1 and Horizon 3) separated by phosphatic limestone (Horizon 2). The focus of this study is the evaluation of the two phosphorite horizons in an area covering about 80 km2 using geostatistical techniques. The study was based on a number of samples derived from 170 drill-holes. Statistical analysis was performed to determine the sampling distributions of the variables: usd\rm P\sb2O\sb5usd%, thickness and accumulation. The results indicate that usd\rm P\sb2O\sb5usd% values are approximately normally distributed. The distributions for both thickness and accumulation are assymetrical with positive skewness. Semivariogram in different directions were constructed leading to the determination the spherical models used in subsequent kriging and conditional simulation. The simple kriging technique was employed to estimate the usd\rm P\sb2O\sb5usd% in blocks with 1000 m x 500 m x 0.5 m dimensions. The study shows that Horizon 1 contains approximately usd1008\times 10\sp6usd tonnes at an average usd\rm P\sb2O\sb5usd grade of 20%, while, Horizon 3 contains approximately usd553\times 10\sp6usd tonnes at an average usd\rm P\sb2O\sb5usd grade of 18%. Conditional simulation was also carried out to derive simulated values of usd\rm P\sb2O\sb5usd% in the two horizons. The results indicate the fluctuation pattern of usd\rm P\sb2O\sb5usd% within the deposit.