Within ADCO, horizontal drilling has been used successfully to enhance well productivity, injectivity, and to reduce water coning in some production wells. This paper presents a case history of how horizontal drilling has been used to reduce the effects of water slumping between psuedo-reservoirs, resulting in reduced water cut and increased productivity; and reservoir simulation efforts to match and predict well performance.
A short radius horizontal hole of 850 ft length was drilled in the dry Thamama B Lower pseudoreservoir in an existing well in the Asab field, and succeeded in reducing water slumping from the wet upper pseudo-reservoir. This resulted in a reduction in the water cut from 20% to less than 1% with a five fold increase in the well productivity. A simulation model of a reservoir element was constructed with local grid refinement to represent the horizontal well. Past performance of the well was matched and the model was used to predict future well performance.