A New Chemical Additive for Preventing Shale and Marl Layers from Swelling During Well Operation

Abstract

The collapse of shale and marl layers is a significant challenge in drilling oil and gas wells.The suitable fluid must have tailor-made rheological properties to assist it in dissolving and dispersing clay minerals especially Illite, Montmorilonite, Chlorite, and Kaolinite. Production of this kind of fluid demands in depth geological and drilling studies on shaly-marly formations. Various drilling fluid chemical additives including glycol, which is customarily used in South oil regions of Iran, were investigated and drilling problems in marl and shale layers are discussed. In the following sections an account of seven wells from the Marun field encountering stuck pipe is given. Details of these cases such as depth of stuck pipe, pipe releasing approach and new types of utilized fluids are also presented. Experiments were conducted with a tablet-making metal apparatus to study the effectiveness of proposed substances on dispersion of shale and marl formations and overcoming the stuck pipe problem in the Petroleum laboratory.