The middle Sarir Sandstone reservoir in the north portion of the Messlah Field, Sirt Basin, east-central Libya, lies along a broad northeast-dipping structural flexure that houses a weak eastward-plunging anticlinal nose near its southern extremity. Over a major part of the field the structure is a homoclinal and the strata are divided into two major depositional periods above and below by a pronounced intra-Cretaceous unconformity, representing the Lower Cretaceous and post-unconformity Upper Cretaceous. Three wells were chosen for this study (well A, well B, and well C), which are located in the northern portion of Messlah Field, which is in the Eastern Embayment of the Sirt Basin Middle Sarir Sandstone. The Sarir Field produces a sweet and light paraffinic crude of 39.6° API gravity, with a low sulphur content. The productive Upper Sarir Sandstone reservoir averages 17% porosity and 500 mD permeability. The average gross pay is 136 ft. The average original oil-water contact is at 8658 ft below mean sea level, and extends for over 200 km². The net pay and reservoir cut offs are <30% volume of clay, >10% effective porosity, and <60% effective water saturation. Well A, which is located on the right of the study areas, is the deepest of the three wells, includes all of the zone formations, and has the greatest amount of hydrocarbons, especially light hydrocarbons. Well B is located between the other two studied well and does not include all the zone formations. Well C is located on the west side of the study area in which the Lower Acacus reservoir has the minimum thickness and hence has the lowest amount of hydrocarbon saturation compared to the other two wells, containing mainly heavy hydrocarbons. The L4 type formation only existed in well A, pinching out towards the other wells. Also, the L5 type formation thickness decreases towards well C.