Theoretical Modeling And Application Software Development For Underbalanced Drilling Design

As well known, Underbalanced drilling has currently become a more advanced dirllingtechnology in the domestic, even in the world. But there still exist lots of technical diiffcultiesin underbalanced dirlling technology. Currently the underbalanced dirlling technology inChina is backward, low pressure and low permeability reservoirs are distributed relativelywidely and the cost of exploration and development continues to increase. Especially there isno a relatively sound underbalanced dirlling sotfware in China yet. Based on the informationabove, ifrst, this paper does a comparatively in-depth study on the basic theory andcalculations in the underbalanced dirlling, such as gas drilling，foam dirlling, aerated drilling,and so on. Then it sets up the correlation calculation model and sotfware model ofunderbalanced dirlling. Last, a set of relatively sound sotfware for hydraulic calculation ofunderbalanced drilling is compiled by using the c#language, and the solfware can achievemany correlative calculation of underbalanced drilling. The work of this paper mainly includesfour aspects. Firstly, it analyes the technical difficulties, which the underbalanced drillingdesign is faced with, and the prominent problems, which need to be solved, and it alsoestablishes the overall structure of design sotfware of underbalanced drilling using computertheory; secondly, it builds the realizable computation model which is used to calculate thereasonable negative pressure in underbalanced drilling; thirdly, for gas drilling，it determines areasonable calculation method of gas injection volume and establishes the relevant calculationmodels; fourthly, it uses the database technology in computer science and the correspondingprogramming method to implement this sotfware system. This system is of important practicalsigniifcance for improving the stability, the reliability and the relative predictability ofunderbalanced dirlling.