连通气层地层压力系数计算方法

Calculation Method of Formation Pressure Coefficient of Connected Gas Layer

地层压力系数是钻井泥浆密度的决定性参数,适当的泥浆密度能够在防止井喷、保证安全的前提下减少气层泥浆的侵入量,降低对储层的污染,提高气井的产能;同一气层一般存在较大的高度差,在流体重力的作用下不同深度地层压力系数存在差异,新钻井的泥浆密度若直接采用邻井的压力系数确定往往不能与地层压力相匹配。所述的地层压力系数计算方法主要思路是:根据连通气层内已取得的地层压力数据,基于天然气高压物性计算方法按深度增量迭代计算连通气层内不同位置、不同深度下的地层压力及压力系数,从而获得满足工程需要的结果。

The formation pressure cofficient is the decisive parameter of the drilling mud density.Ap-propriate mud density can reduce the intrusion of gas layer mud,reduce the pollution to the reservoir,and improve the productivity of gas wells under the premise of preventing blowouts and ensuring safety.If the height difference is large,the formation pressure coefficient at different depths is different under the action of fluid gravity.If the mud density of the new drilling is directly determined by the pressure coefficient of the adjacent well,it often cannot match the formation pressure.The main idea of the calculation method of formation pressure coefficient described in this paper is:according to the formation pressure data obtained in the connected gas layer,based on the natural gas high pressure physical property calculation method,it-eratively calculate the formation pressure at different positions and different depths in the connected gas layer according to the depth increment and pressure coefficient to obtain results that meet engineering needs.