Research On Prediction Model Of Sand Production In Water Producing Gas Wells

Through the gas reservoir production practice for many years, we find that sand production has become one of the major factors for gas reservoir exploration in the process of gas reservoir exploitation. After decades of sand production prediction research, scholars both at home and abroad has obtained certain achievements and understanding in the field of sand production prediction, and established a lot of sanding prediction model. To a certain extent, the sand production prediction model promotes the development of the sand production prediction technology, and has an important guiding significance for the production practice of oil and gas field. However, the research content that involved in this field is very wide, and the research itself is very complex, also need further study to further improve the gas well sand production prediction model existing.Water invasion is inevitable in the process of gas reservoir exploitation, it is also an important cause of sand production in natural gas. The water produced from the gas well can affect rock mechanics properties of formation rock, thus affect gas well sand production. About the problem that Water production gas well produces sand, the author of this paper, from the perspective of the relationship between rock mechanics parameters and water saturation, combined with the percolation mechanics and elastic-plastic mechanics, reservoir numerical simulation theory, research the water production gas well sand production prediction model. The main research contents and conclusions are as follows:(1)By using material balance principle and Darcy seepage law of two-dimensional gas water two phase flow model is established, and the finite difference model for using IMPES method was used to solve mathematical model. Using Visual Basic language to compile calculation program of the two-dimensional two phase seepage, the program can calculate formation fluid distribution of pore pressure and water saturation distribution, provide Basic data for subsequent water production gas well sand production prediction.(2)By testing the rock mechanics parameters, I found the water saturation has obvious influence on rock mechanics parameters, the rock elastic modulus and compressive strength exponentially decline with the increase of water saturation, and established the relation between the rock elastic modulus, or the compressive strength and water saturation, provide the basis for water production gas well sand production prediction model introduced water saturation parameters.(3)Based on the research of the rock mechanics parameters, I found the water saturation also affects the size of the cohesion of rock, and has carried on the correction to Mohr-Coulomb failure criteria to make it suitable for gas well produced water sand under the circumstance of judgment.(4) Combining with the influence of water saturation on rock mechanical parameters, correcting the Mohr-Coulomb failure to make it suitable for water-production gas well. Combining with the elastic zone stress distribution model and modified Mohr-Coulomb failure criterion, I established the critical pressure difference prediction model for water production gas well out of the sand; Combining with elastic stress distribution, plastic zone model, I established the stratigraphic rock damage and cause the sanding radius sanding prediction model when the water production gas well production pressure difference is greater than the critical pressure difference.(5)Using the Visual Basic language, I compile sand production prediction program for the water production gas well sand production prediction model established. Through this program, I have carried on the calculation to a mass of water gas well, predict the sand production of gas well radius of critical pressure differential and sand production, and analyze the geological factors and production factors on sand production critical pressure differential and sand radius of influence.