fluid invasion from water-based drilling mud (wbdm) into the shale formations causes swelling,high pressure zone near the wellbore wall, and eventually wellbore instability problems duringdrilling operations. for the stability of the wellbore, physical plugging of nanoscale pore throats couldbe considered as a logical approach toward avoiding the fluid invasion into the shale formation. thispap...

Wellbore instability in oil and gas drilling is resulted from both mechanical and chemical factors. Hydration is produced in shale formation owing to the influence of the chemical property of drilling fluid. A new experimental method to measure diffusion coefficient of shale hydration is given, and the calculation method of experimental results is introduced. The diffusion coefficient of shale ...

This study performs a comprehensive comparison of three key marine shale reservoirs in the southeastern margin of the Sichuan Basin, and explains why commercial gas production was only achieved in the Lower Silurian Longmaxi (LSL) and Upper Ordovician Wufeng (UOW) formations, but not in the Lower Cambrian Niutitang (LCN) formation. The experimental methods included in situ gas content and gas c...

S hale resource systems have had a dramatic impact on the supply of oil and especially gas in North America, in fact, making United States energy independent in natural gas reserves. These shale resource systems are typically organic-rich mudstones that serve as both source and reservoir rock or source petroleum found in juxtaposed organic-lean facies. Success in producing gas and oil from thes...

Some studies reported that the anisotropic failure strength of shale will be weakened by increasing confinement. In this paper, it is found that there are various types of anisotropic strength behaviors. Four types of anisotropic strength ratio ( S A 1 ) behaviors and three types of anisotropic strength difference ( S A 2 ) behaviors have been classified based on laboratory experiments on nine ...

This study concerned a stretch of 17 km of a 94-km highway alignment in Southeastern Nigeria that has a high incidence of pavement failure arising from subgrade failure. The subgrade of this section of the roadway is composed of Ekenkpon shale, New Netim marl, and Nkporo shale. Under the Unified Soil Classification System, the shales classify as OH (organic clay) and the marl classifies as MH (...

fluid properties with constant improvement in efficiency have been noticeable as important criteria in drilling operation. the main drilling fluid properties highly depend on utilization of new polymers with high efficiency in drilling fluid composition. in this paper, the performance of a new polymer, called partially hydrolyzed polyacrylamide polymer (phpa), is studied which has recently ente...

Optimization of drilling fluid parameters such as mud weight, salt concentration, and temperature is essential to alleviate instability problems during drilling through shale sections. The selection of suitable mud parameters can benefit from analyses that consider significant instability processes involved in shale-drilling–fluid interactions. This paper describes the development of analytical...

To investigate the disintegration and microstructure characteristics of carbonaceous shale in high-latitude cold regions, indoor, outdoor, initial particle size, freeze–thaw experiments were conducted concerning dry–wet cycles. Two tests performed: sieving microscopic scanning electron analysis. The disintegration, size variation rule, resistance, fractal studied. variations rock before after w...

Starch is one of the most widely used biopolymers in water based drilling fluids to control fluid loss. The thermal stability of starch in common drilling fluids is low (93 °C). In this study, the thermal stability of starch has been evaluated in sodium/potassium formate and potassium chloride fluids. Samples of mud were prepared by formate salts (sodium and potassium) and potassium chloride wi...