Basin analysis study of block 10 in the Say'un-Masilah Basin, Yemen, using a 1D backstripping method

摘要

Geohistory analysis was carried out on block 10 in the Say’un-Masilah Basin. The present study is based on the analysis of the well logs of six exploration wells. In the Middle Jurassic to the Middle Eocene, Say’un-Masilah Basin exhibited a complex subsidence history over a period of about 155 Ma. Backstripped subsidence curves are constructed by removing the effects of decompaction to the water column and sediment loads. In the Middle Jurassic, slow subsidence was driven under the effect of sediment load as Kuhlan and Shuqra Formations were deposited as pre-rift deposits. The average total subsidence value of the basement during the deposition of Shuqra Formation was 276 m. The highest subsidence rates during this time are observed northeast of the study area. Rapid subsidence initiated in the Upper Jurassic driven by mechanical extension of the rift, resulting in the deposition of Madbi and Safer Formations, or the so-called Syn-rift deposits. The average tectonic subsidence value of the basements during the deposition of Madbi Formation was 368 m. The highest subsidence rates during this time are observed southwest of the study area. Mechanical extension ceased at about 145 Ma, being replaced by a phase of post-rift subsidence, resulting in more widespread uniform sedimentation, with reduced tectonic subsidence rates forming post-rift deposits represented by Nayfa Formation, Sa’ar Formation, Biyad Formation, and Mahra Group. The total subsidence value of the basement during the deposition of the post-rift sediments increases gradually due to the increase of the sediment load as the rate of deposition was high especially northeast of the area.