Implementation of ROP Management Process in Qatar North Field

Abstract

Abstract In March 2005, the operator implemented a rate of penetration (ROP) management process in Qatar's North Field. IPTC Paper 10706-PP describes the general principles behind the new work process and highlights its introduction to the operator. The ROP management process uses real time, customized surveillance technology to continuously maximize both drill bit cutter efficiency and transmission of energy from rig floor to the bit. This paper focuses on specific changes in drilling practices and their translation into substantive program acceleration and capital savings. To date, the development program has been accelerated by one year and USD 54 million has been saved while drilling 470,000 ft of hole. The process has proven to be a highly effective solution for management of drilling efficiency in a major development drilling campaign. As an indicator of program scope and effectiveness, over 440 personnel have been trained in mechanical specific energy (MSE) analysis, and 50 new field drilling records have been set by the nine rigs involved in the program. Importantly, the process has been implemented with one of the best safety records in industry (TRIR or total recordable incident rate of 0.11 per 200,000 man-hours as of September 06). Introduction The Qatar operator currently conducts drilling operations with nine rigs at eight platform locations across six very large producing blocks, each typically a 12 × 12 km concession. The majority of wells are drilled in batch mode by section, an approach adopted in the late 1990's when development drilling began. Over the years, the operator gained extensive field knowledge and developed many efficient operating practices. Thus, the introduction of any new ROP management process would be scrutinized and assessed against solid baseline operating performance. At the same time, 2005–2006 has been a period of transition, as the company increased rig count from three to nine rigs. The addition of many new support personnel in a multi-cultural working environment presented a significant challenge in terms of maintaining or improving drilling efficiency. This was coupled with high service personnel turnover, which continues to pose operational challenges. In the face of these challenges, it was decided to pilot test the ROP management process, with its first application in such an extensive carbonate field environment. The focus of the program was fourfold:conduct extensive, customized field training in MSE analysis;implement a standard surveillance program;introduce new practices in a phased manner concurrent with measurement of energy efficiency; andsystematically communicate learning across all rigs using MSE curves as the basis for discussion. This paper discusses summary learnings and offers technical examples of how MSE is being used to achieve consistently better drilling results. Specifically, the role of lithology, the general approach used to manage efficiency, ROP limiters encountered, and BHA optimizations will be discussed. While learning specific to the North Field is presented, the information is applicable to many drilling areas. Qatar North Field Background Figure 1 shows the location of the North Field offshore Qatar. Figure 2 shows both stratigraphy and typical wellbore configuration. Aside from one vertical data well at each platform location, all wells drilled by the operator are 55–65° S-shaped directional wells with an abbreviated drop section into the Khuff reservoir. Although platforms are kilometers apart, many wells are quite similar in terms of lithology, hole size, casing configuration, and casing setting points. An important reference data set when discussing MSE is rock unconfined compressive strength (UCS), presented in Figure 3. The MSE recorded while drilling should vary as the bit traverses rock of various strengths. However, it should only vary by the amount of change in rock strength. In field operations, a baseline MSE is established and any increase above this that exceeds the change in rock strength is likely to be an indication of bit dysfunction. The trending nature of MSE surveillance is described in IPTC Paper 10706-PP. It should be noted the efficiency gains described in this paper are only those directly attributable to the ROP management process in 17–1/2″, 12–1/4″, and 8–1/2″ sections.