Drilling Simulation versus Actual Performance in Western Canada

Abstract

Abstract During the past two years a drilling performance simulator has been applied in a pre-drill mode to more then 50 wells with an average depth of 3000 meters in Western Canada. The main goal of applying the simulator was to optimize the drilling performance by increasing rate of penetration (ROP) and decreasing drilling time and costs. To maximize performance the correct bits, hydraulics, operating parameters and pull depths were selected in advance. The drilling simulator uses offset well drilling data and records to generate the apparent rock strength which is then correlated to the formations depths for the new well to be drilled. Multiple combinations of drill bits and operating parameters are simulated to obtain the optimum drilling solution for the next well. The results indicate very good match between predicted and actual field results for ROPs as well as total drilling times and well costs. The simulation approach initially easily matched pacesetter performance of previously drilled wells in the mature field and then by further applying the simulator new pacesetters where set improving performance overall with more then 15 percent. The presimulated optimized results were sent to the field and during the drilling of the well the field data was overlaid with the presimulated field data to compare progress. During the drilling follow-up the bit wear and apparent rock strength calculated from the field data were compared to the presimulated to evaluate the current status of the bit and drilling progress. The follow-up process gave room to take immediate actions and a baseline for communication with the field and office during daily meetings. This paper presents the commercially available simulator and multiple cases which compares the pre-simulated to the actual performance. The results clearly indicate the large potential for the use of such a simulator in drilling operations. Introduction A drilling optimization software, the "Optimizer" uses offset drilling data and records from offset wells in an area and through inverted ROP models predicts the drillability or Apparent Rock Strength Log (ARSL). The ARSL describes the drilling resistance for the different formations on a meter by meter basis. The current process of calculating the ARS from the "Optimizer" involves the use of a reference well that closely matches the geological characteristics of the planned well. The drilling inputs (weigh on bit (WOB), bit rotational speed (RPM), flow rate, mud weight, bit wear, ROP, detailed bit type and design etc.) of the reference well are used to solve the ROP equations with respect to the drillability or the ARSL for the reference well. The ARSL2–3 has also been seen to correlate well to log properties. The strength log from the reference well is further either stretched or shrunk to fit the geological prognosis for the upcoming well to be drilled. This is done by combining the directional well plan for the new well with the true vertical depth ARSL log created from the reference well and then the formation tops are matched to the new survey. The optimization of the drilling process for the upcoming well is then a straight forward process. The simulator predicts the ROP for the new well, with the adjusted ARSL, for different drilling scenarios. This involves trying multiple combinations of drill bits and operating parameters before finally reaching the optimum drilling solution. The use of a drilling simulator has proven that it can significantly improve results with the input of an accurate ARSL4–5. Application A drilling simulator was applied in Western Canada more specifically north-eastern British Colombia and central Alberta. The purpose was to see if more rapid learning could occur and a break in the learning curve could be seen in some semi-mature fields by utilizing a drilling simulator. The process of how the optimize the drilling of a new well involves a pre-planning and a follow-up phase with constant communication between field and home office.