|
Drilling accidents of the tight hole, collapsing, drill rod sticking and burying appear in deep drilling when the bore meet the water sensitive formation. Geological and engineering factors which affect the tight hole are analyzed. Calculate model is set up with mechanics, chemistry and metabolize analyzed which can provide theory condition for reasonable engineering measure against tight hole. The late-model drilling fluid is obtained which can balance the pressure with geological stress and be applied broad. The author finds the drilling fluid capabilities needed in this composite formation according to the elements, and designs the testing system for testing the drilling fluid capabilities. Meanwhile, the drilling fluid material with high performance price ratio optimization ally is selected to use in the projects according to the project and obtained preferable efforts finally. Many experiments and much data can support this fluid system which comprises the chemical matter and filtration control agents. A new evaluation criterion is established to observant the capabilities of the drilling fluid used in this composite formation from a different view. A few compounding with high performance price ratio and well capabilities have been optimized and selected according to the work theory of the fluid additives, the evaluation method of the fluid capabilities and the project realities in water sensitive-unconsolidated formation which has been used in some projects and successes in avoiding bore accidents, decreasing project period and saving cost. It is applied in the CCSD-SK successfully. As the project of gravely geology event and greenhouse climate change in the cretaceous period of the earth surface, it is located in the Tahala Conformation belong to the Gulong Sunken Stratum in Songliao Basin. At first, the fluid system has been in the role of rejecting expansion in mud shale and agglutinating protecting sand rock collapsing. But there is a disadvantage of system which is it has bad incompatibility with other additives. So it is hard to adjust and compound system with other systems to settle the questions may appear in further drilling. Then another fluid system has been using in the second project, from now on the effect is well. For the questions of salt infusion and weighting which may appear in further drilling step, it has obtained several kinds of the former fluid systems which can satisfy the needs in drilling. Otherwise, it is necessary to reach and improve the anti-temperature and fungi-proofing capabilities of this fluid system because there are many vegetable gelatins materials in it. Although much running in and lifting drilling tools work is done in the water sensitive and grit formation, the bore is integrated based on this drilling fluid system.
|
