Interference and pulse tests at horizontal wells introduce features and issues that require specific procedures for evaluation and analysis. In addition to reservoir properties, it becomes necessary to account for three-dimensional pressure distributions, as horizontal wells tend to be rather long. The objective of this paper is to discuss the effect of the existence of a horizontal observation well on the analysis of interference tests. We use a semi-analytical model for interference testing with a horizontal observation well. The conductivity of the horizontal wells may be infinite or finite. We discuss the flow regimes in the observation well. The effect of anisotropy is shown to significantly affect the interference between two horizontal wells. In many practical situations, it becomes necessary to evaluate such tests by numerical means. At this time, no simple method exists to calibrate observation well responses computed by numerical simulators. The results of this study should provide for an accurate measure of pressure responses to calibrate numerical simulators. Introduction Analysis of horizontal well responses is considerably more complex than that for their vertical counterparts.1 Similarly, interference between two horizontal wells may create complex pressure transients that may not be correlated by the interference between two vertical wells.2 The complexity of the horizontal well interference responses significantly increases when the reservoir becomes more heterogeneous. In fact, considering the long reach of horizontal wells, homogeneous reservoir assumption may not be realistic for horizontal interference test analysis. Therefore, in many practical situations, horizontal well interference tests need to be evaluated by using numerical simulators. Considering the inherent problems of modeling horizontal wells in numerical simulators, especially for transient analysis purposes, and the fact that the details of flow in and around the horizontal observation well also needs to be captured, the numerical models used for horizontal well interference tests have to be sensitively calibrated. Analytical models required to calibrate numerical simulators for horizontal well interference testing have not been reported until now. The objective of this work is to present a semi-analytical model that can be used to investigate the fundamental characteristics of horizontal interference well responses and to provide a means to calibrate numerical simulators. The model consists of the superposition of the responses of two finite-conductivity horizontal wells. Fluid withdrawal (production) from one of the horizontal wells is considered at a constant rate. The second horizontal well (observation well) is shut in at the heel (for simplicity, we do not consider the effect of wellbore storage in this work) but fluid may enter (production) and leave (injection) this well along its length with total production being equal to total injection. Both pulsing and interference wells may have an arbitrary skin distribution along their lengths. We have developed the solution presented in this work by using the finite-conductivity horizontal well model discussed in Refs. 3 and 4. The model provides the pressure drawdown at the heel ends of the pulsing and observation wells, as well as the flux and pressure distributions along both horizontal wells. Therefore, the model can be used to investigate the effect of interference not only at the pressure measurement points (the heels of the wells) but also to understand the local changes in and around the wells. Below, we first introduce the physical system considered and present the semi-analytical model. We, then, consider some example cases to discuss the responses of both active and interference wells. We investigate the effects of anisotropy, skin, and finite wellbore conductivity. Finally, we highlight the error that might be caused by ignoring the effect of the length of a horizontal interference well (that is, treating the observation well as if it were a vertical well). We also compare the horizontal well interference test results with those for the situation where both wells are vertical.

The first practical coriolis mass flowmeter was introduced in 1977. Today, there are several manufacturers which offer various coriolis mass flowmeters with different sensing tube configurations and geometry. These meters continue to evolve, gain wide acceptance, and are used in the chemical, petroleum, food and beverage industries because of the several features that they posses over other types of flow measurement devices. This paper presents a performance evaluation of three types of coriolis mass flowmeters: U-tube, modified U-tube, and straight tube meters. These meters were individually tested in a compact multiphase test unit (WellComp) located in an onshore area of a field in Saudi Arabia. The test results obtained from these meters were compared with simultaneous data obtained from turbine meters installed in a conventional test separator.

Summary One of the common assumptions in horizontal-well interference-test analysis is to ignore fluid flow in and out of the horizontal observation well and represent it by a point. In some cases, the active well is also approximated by a vertical line source. Using a semianalytical model, this paper answers three fundamental questions:• What is the critical distance between the wells to represent the horizontal observation well by an observation point?• Where should the observation point be placed along the horizontal well?• Under what conditions may the active well be approximated by a vertical line source and the exponential integral solution be used to analyze observation-well responses? Two correlations are presented to simplify the analysis of horizontal-well interference tests. Example applications are presented, and error bounds are documented. Introduction Analysis of horizontal-well interference tests is an extremely difficult problem because the lengths, orientations, locations, and distances between wells need to be considered. One of the assumptions used to make the horizontal-well interference-test analysis a tractable problem is to ignore the flow pattern that results because of the existence of the horizontal well and to treat the horizontal observation well as an observation point. It also has been suggested that if the distance between the two wells were sufficiently large, then the active horizontal well could be replaced by a vertical well. In this case, the observation-well responses may be approximated by the exponential integral solution, and the analysis is reduced to the conventional interference-test analysis between vertical wells. For the application of the approximate analytical techniques, two questions need to be answered. The first question is whether the distance between the two horizontal wells is large enough for the geometry of the wells to be ignored. Malekzadeh investigated this question by considering the interference between a horizontal active well and a vertical observation well in an isotropic reservoir. Because anisotropy has a major effect on the pressure-transient responses of horizontal wells, the results of Malekzadeh have limited applicability. In addition, the influence of the geometry of the observation well cannot be deduced from the model used by Malekzadeh. The second question is, where should the equivalent observation point (EOP)be placed in the reservoir if the horizontal well were to be replaced by a vertical well? This question has yet to be addressed in the literature. The EOP is defined as the location at which the pressure recorded at the heel of the horizontal observation well would exist in the absence of the observation well. Because of the lack of theoretical guidance, the physical location of the heel or the center of the observation well is usually chosen as the observation point.1 But such an assumption ignores the fact that fluids enter and leave the horizontal observation well although there is no surface production. Therefore, some disturbance of equipotential lines around the observation well should be expected. Thus, if the horizontal well were to be removed from the system, we may expect the pressure recorded at the heel of the horizontal well to exist at a different location. The location of the EOP would be a function of the variables that determine pressure at the observation well. This work uses a semianalytical model to answer the above questions. The model has been discussed in detail in Refs. 4 and 5 and is capable of considering interference between two horizontal wells in a homogeneous but anisotropic reservoir. Based on the results of the semianalytical model, two correlations have been developed to significantly simplify the analysis of horizontal-well interference tests without sacrificing accuracy. The first correlation provides the location of the EOP, which has not been available in the literature. The second correlation provides information on the distance under which both horizontal wells may be treated as vertical wells and the exponential integral solution may be used to analyze the interference test. Compared with the correlation presented by Malekzadeh, the correlation presented here is more comprehensive because it accounts for the effects of anisotropy, location of the EOP, and relative position of the wells. To assess the adequacy of the correlations, error bounds have been calculated and are documented in this paper. The correlations enable us to analyze horizontal-well interference tests by the single-horizontal-well solutions or by the exponential integral solution. The convenience of the single-horizontal-well models for the regression techniques used in well-test-analysis software becomes clear if the computational complexity of the rigorous horizontal-well interference-test models4,5 is noted (the increase in the speed of computations is usually more than six-fold).

Nowadays, with the advanced technology, there is a large quantity of real time data that flows from the equipment in the field to the engineers’ desktop. The quality of data is, in most cases, questionable. A high quality data is required to be utilized in production workflows and technical studies. Failure to acquire reliable data will affect the calculations of production parameters, hence impacting the overall understanding of well performance. Therefore, monitoring data reliability and quality is essential. A project was initiated to tackle all various reliability issues for eight fields where a focus team was formulated. The team assessed the current data reliability and facilitated developing the action plans with the use of Lean Six Sigma concept which follows five phases; define, measure, analyze, improve and control. Multiple tools such as fishbone diagram and 5-WHY were used to identify the root causes for having reliability issues along with a correspondent solution (s) which aided developing a detailed implementation plan. The project goal is targeting an increase in overall data reliability in a six-month period. An anticipated increase of 5% to overall data reliability is to be achieved post to the tags deletion and re-mapping campaign. It is worth mentioning that the utilization of production workflows through effective monitoring of wells rate compliance and ESP is associated with remarkable cost saving. Securing high data reliability from various equipment will enable engineers to track the wells’ rates and status at their desktops. Moreover, effective monitoring of ESP performance will help preventing the occurrence of trips and optimize ESP operations in the field. Last but not least, effective data monitoring will ensure the upkeep of the Intelligent Field equipment.

With the ever growing demand for energy in the world, the need for timely and accurate data from oil fields to allow proper decision making becomes very crucial. Recent evolution in oil field technologies has made a great revolution in the oil and gas industry all over the world, leading to the emerging development of intelligent fields (I-Fields) 1-4 . The integration of I-Field technologies, whether downhole or at surface, coupled with communication networks along with sophisticated simulation and monitoring applications has led to significant advancements not only in monitoring and control capabilities, but rather also in decision making processes 5 . Therefore, the overall system upgrade has resulted in an enhancement of the field surveillance, which will lead to higher levels of oil production in these assets as a consequence of Saudi Aramco's development strategy for these fields.