Wang Zhizhan

Determining the fluorescent components in drilling fluid by using NMR method

Fluorescent additives can reduce drilling operation risks, especially during high angle deviated well drilling and when managing stuck pipe problems. However, they can affect oil discovery and there is a need to reduce the level of fluorescents or change the drilling fluids to prevent loss of drilling velocity and efficiency. In this paper, based on the analysis of drilling fluids by NMR with high sensitivity, solid and liquid additives have been analyzed under conditions with different fluorescent levels and temperatures. The results show that all of the solid additives have no NMR signal, and therefore cannot affect oil discovery during drilling. For the liquid additives with different oil products, the characterizations can be quantified and evaluated through a T2 cumulated spectrum, oil peak (T2g), and oil content of the drilling fluids. NMR can improve the application of florescent additives and help us to enhance oil exploration benefits and improve drilling operations and efficiency.

A new method for detecting real-time geopressure from drilling-logging parameters

Real-Time detecting abnormal formation pressure can not only prevent the happening of drilling hazard, but also effective protect the pollution of reservoir. A detective model can be made from some drilling-logging parameters because these parameters collected by comprehensive logging instrument can indicate the abnormal pressure information existing in the formation. First, a PCA method is used to process six wells from Dongying Depression, China in order to reduce the cross-correlation among parameters and the count. Then a neural net model is trained by the result in the first step. Finally, thirty wells are detected by the model. The correspondence between real data and predicted results is about 84.6%. So this method can be used in the real case.