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Drilling operations became more expensive and complicated day by day due to many reasons affecting directly the daily drilling cost. One of the most effective cost reductions was the fixed cutter bit solution which effectively achieved higher drilling progress and reduces overall well cost. Also, in some cases PDC bit may raise the well cost due to slow down in the penetration rate or stopped drilling to retrieve mechanical parts from the hole due to bit fatigue and followed by extra trips for junking or fishing operations. The present study focuses on most of the factors affecting fixed cutter bit design, drilling parameters that influence the bit cutting structure wear and led to the bit poor progress. All previous PDC bit mathematical models used before for determining the cutters wear value not considered real methodology on rig site to assure cutters wear and gives a proper decision to terminate the PDC bit run. Study investigated four mathematical models had calculated the PDC cutters wear using the influences of the rock strength, rock temperature and mechanical drilling parameters. These models are theoretical and applied within the lab test devices, most of models not achieved significant benefit to use in rig site applications. New model had developed to compute PDC wear value as function of surface torque arises from the friction between the drill string, bit interaction with well bore and rock on bottom. Both resistance created by the string and bit are converted to output data realized by the gauge in front the driller in rig floor and mud logging unit. Analog or digital data reflects the torque obtained from rotating the bottom hole assembly (Drill pipe, string stabilizer and bit) against the wall of hole and formation strength. Mathematical model calculates the theoretical torque for string tool joint, stabilizer and PDC bit cutters allocated in nose up to gauge area. In reality, when BHA rotates off bottom torque created is representing the summation of string tool joint and stabilizer. An additional torque realizes on surface when BHA on bottom and WOB applied then this bit torque value will be compared by model bit torque. This later obtained bit torque percentage that represents the cutters wear value preoperational to cutter height. New mathematical model had created visual analog graphs will help to take decision when stop drilling and terminate the PDC bit run. Field validation test had run in two main concessions in Egypt Western desert and Gulf of Suez with total 6 PDC bit runs using different bit size, type, cutter sizes and different bottom hole assembly (Rotary-steerable). The filed results showed significant correction in cutter wear magnitude between the model calculation and field runs, this error factor less than 10% in hard formation and less than 20% in medium to soft formations. Author set the correction in model and treated in easy way to be used on field by driller and drilling engineers to help them how to determine the PDC bit cutting structure wear value.

Over the years, the discovery of petroleum in various regions of the world has led to the development of different techniques and equipment to enhance and optimize the drilling and production operations in this vital industry. Egypt is both one of the major oil-producing non-OPEC countries and one of the oldest energy producers in the Middle East. Recently, the Egyptian government have signed several agreements for the exploration of oil and gas in several provinces/regions including; the Mediterranean, the Western desert, the Nile Delta, and the Gulf of Suez. Petroleum companies have given great attention to Egypt's new discoveries such as Zohr Gas Field, and Nour exploration prospect. Successful drilling operations to reach the oil and gas targets depends strongly on the effectiveness of the drilling fluids. Drilling fluids can be considered as the heart of the drilling process. They are used to fulfil several functions, such as controlling pressure, carrying cuttings and cooling bit and drill strings, stabilizing wellbore as well as controlling fluid losses.Drilling fluid technology is one of the most targeted and developed technologies worldwide. Several studies have examined the use of various types of nanoparticles (NPs) as additives to enhance the properties and improve the performance of the drilling fluid to mitigate the drilling problems. NPs can be defined as a simplest structure with a size in the range of nanometers. The effectiveness of NPs can be accredited to their small sizes and thus, high surface-area-to-volume ratio. NPs were also showed promising enhancements on the rheological and filtration characteristics of the drilling fluid (mud). Additionally, swelling and collapse of shale formations is expected under drilling with water-based mud, which might result in complicating the drilling operation. Adding NPs to the drilling mud was found to minimize the shale permeability and thus, promote the wellbore stability.This research paper discusses the latest applications and presents the most valuable findings concerning the efficient use of NPs in the drilling fluid industry. Based on that, different recommendations are stated. This might help researchers to better understand NPs' functionality in this area of application and promote using NPs-based drilling muds as cost-effective and environmental-friendly fluids to drill the Egyptian oil and gas wells.