Horizontal gas-storage wells can increase deliverability

Horizontal drilling with special attention to the requirements of gas-storage zones can yield wells with deliverability about six times that of comparable vertical wells. Although horizontal-drilling technology used on development wells can be successfully applied to gas storage, there are several major differences that must be considered during both planning and drilling. Special areas of attention include reservoir evaluation, formation characteristics along the well path, target objectives, and well design. The well planning includes well location and target, hole size, tubular program, well path, radius, and horizontal objectives. These factors directly affect the bottom hole assembly (BHA) configuration, drillstring components, casing program, and drilling-fluids program. Consideration of these drilling factors during well planning can minimize the time required to complete the project and reduce risk. Contingency plans for each phase must be prepared and ready. Additionally, constant open communication between all participating parties is essential for success. Reservoir analysis, prespud planning, and a team approach to drilling engineering involving both operator and contractor are keys to a successful project. The paper describes gas-storage wells, planning, reservoir modeling, re-entries, well completion, drilling engineering, bottom hole assembly selection, bit selection, downhole motor, MWD tools, orienting sub, drillstring, casing program, and drilling fluids.